101 Results
Periodic Table Live! Tutorial (part II)   
(Other (1))
Look here for a tutorial to guide you through the use of the Periodic Table Live! It is in the form of 2 power point files which you can download. We recommend opening up your web browser and trying things out as the power point suggests.
Molecular Models of Indicators   
(Interactive Simulation (1))
The article by Nicholas C. Thomas and Stephen Faulk on "Colorful Chemical Fountains" (1) reminds us that color—the colors of acid–base indicators or of metal complexes—is responsible for many of us developing an interest in chemistry. The featured molecules this month are the acid and base forms of three common indicators–phenolphthalein, methyl orange, and methyl red. These three substances display interesting structural features as the pH-induced transformation from one form to another takes place in three different ways. In the case of phenolphthalein, the lactam ring is cleaved on deprotonation to produce a carboxyl group with the concomitant removal of a proton from a phenolic group. In methyl orange, one of the nitrogen atoms is protonated in the acid form, and that proton is lost in the base form. In methyl red, a carboxylic acid function is deprotonated. There are many other interesting aspects of acid–base indicators. Since most plants and fruits contain pigments that show a color change in some pH range, it is difficult to state with any degree of certainty when these changes were first put to use in a systematic fashion. The Spanish alchemist Arnaldus de Villa Nova (Arnold of Villanova) is purported to have used litmus in the early 14th century. In general systematic use of indicators is traced to the latter half of the nineteenth century with the development of the three synthetic indicators described above. Many students will be familiar with the use of phenolphthalein to identify blood—often shown on the various forensic chemistry TV dramas by dropping some solution on a cotton swab that has been used to pick up some of the sample in question. If the swab turns red we frequently hear "It's blood". The reality of using phenolphthalein in this way is more complicated. The test is presumptive for the presence of blood, but not conclusive. It is not an acid–base reaction but rather, in the presence of hydrogen peroxide, relies on hemoglobin to catalyze the oxidation of phenolphthalein. An interesting assignment for students in a high-school or non-majors course would be to have them explore the details of this Kastle–Meyers test to see just what is involved in the correct application of the test, and what factors complicate the process. For example, would tomato juice infused with asparagus juice give a positive Kastle–Meyers test? Historically phenolphthalein was used in a variety of laxatives. Recently that usage has been discontinued due to concern about the carcinogenic nature of the substance. A review of the history of the controversy surrounding the use of phenolphthalein in laxatives would make a good research paper at the high-school level. Lastly, students with some practice building structures and performing calculations might wish to explore the structures of two other forms of phenolphthalein—one found in very acidic solutions, having an orange color, and one found in very basic solutions that is colorless.
Molecular Models of Annatto Seed Components   
(Interactive Simulation (1))
In January 2008 the focus of this column was on the plant pigments lycopene and beta-carotene (1). Our attention this month returns to two papers discussing the pigments in annatto seeds (Figure 1), including direct precursors to lycopene. The paper by Teixeira, Dur�n, and Guterres describes the extraction and encapsulation of annatto seed components (2). The McCullagh and Ramos paper describes the separation of the pigment bixin from these seeds by TLC and column chromatography (3). These molecules could form the basis of interesting exercises across the chemistry curriculum. In courses designed for non-majors, students could choose a molecule from the table and search the literature for both scientific and non-scientific sources. Are the claims made in the latter sources regarding the health benefits of these molecules consistent with the scientific data? That discussion could be expanded to the more general question of how one tests the validity of statements made in what are essentially advertisements. Are any of these precursor molecules to lycopene considered to have anticancer properties (4)? In introductory or general chemistry courses, students could explore the various bond lengths and bond angles in the molecules to see whether they are consistent with their expectations based on simple bonding models. In introductory, organic, or biochemistry classes, the thermodynamics of hydrogenation and dehydrogenation could be examined. This might make an interesting alternative to the oft-discussed Haber Process. What conditions would one propose for a dehydrogenation process? Why are dehydrogenation reactions important? What enzymes catalyze the various dehydrogenation steps from phytoene to lycopene? These molecules could also be used in a variety of computational exercises in introductory and physical chemistry courses. Hartree�Fock calculations on a molecule such as phytoene may prove time-consuming depending on the nature of the computing system available. A good place to begin would be to perform semi-empirical calculations on the various molecules. Do the optimized structures match experimental results or the results of larger calculations? Does the HOMO�LUMO gap correlate with the observed electronic absorption spectra? Which is more important in determining the difference in absorption between phytoene and phytofluene, the total number of double bonds or the number of bonds in the region of conjugation? Of course the aspect of these molecules that is most likely to capture student attention is their color, and they provide nice examples of the origin of color, the relationship between color observed and color absorbed, and, in upper level courses, the more detailed relationships of the energies of the ground and excited states.
Molecular Models of Leaf Extracts   
(Interactive Simulation (1))
Our Featured Molecules this month come from the paper by Pelter et. al. on the analysis of leaf extracts by thin-layer chromatography (1). As the authors discuss, their experiment may be used in courses at various levels of the curriculum. The molecules discussed in the paper are also of wide interest both for their structural properties and their wide-ranging appearance in both natural and synthetic substances. Included in the molecule collection are all of the isomers for the molecules pictured in the text with the exception of menthyl acetate, for which only one structure is given (see below). All of these molecules have been optimized at the HF/631-G(d) level. The menthol family enantiomeric pairs of menthol, isomenthol, neomenthol and neoisomenthol provide a rich yet coherent group of molecules on which to base discussion of chirality, enantiomers and diastereomers. Treadwell and Black have described some of the differences in physical properties of four members of this family, and several other experiments using one or more menthols have been published in this Journal (2, 3). I have created a Web page in which the eight molecules are embedded in no particular order, and with no rational file names. This is being used in at least one of our organic sections to give students experience at identifying enantiomers, and diastereomers, and in applying R/S notation (4). As access to computational software becomes more common, and as efforts are being made to incorporate more relevant modeling experiments into all levels of the curriculum, the menthols again present some interesting possibilities. While students at the organic level know about enantiomers differing in their optical rotation, and about chiral molecules interacting with chiral and achiral environments, it is instructive for them to think of other ways in which enantiomers and diastereomers are the same or different. Three useful ways of checking to see whether two structures are truly enantiomers is to compute their total energies, vibrational spectra, and dipole moments. These calculations are available in most common computational packages. Figure 1 shows the results of energy calculations on optimized structures of the eight isomers. The enantiomeric pairs have, as expected, exactly the same total energy, while the various diastereomers differ in energy. The computation of the vibrational spectra is a very sensitive probe to determine whether two structures are optimized and enantiomeric or not. Structures that are almost enantiomeric, but not quite optimized, may exhibit similar energies, but the low frequency vibrations will be sensitive to any deviation from optimization. If two supposedly enantiomeric structures do not have the same computed vibrations, or if either shows a negative frequency, the structures need to be optimized more carefully. As with the vibrational frequencies, enantiomers should show identical dipole moments. Only one structure of the eight isomers in the menthyl acetate family is included in the collection, giving students the chance to build the other seven and verify their computed properties. Because of the central role that chirality plays in chemistry, and particularly in biochemistry, it seems appropriate to introduce some of these visualization and modeling exercises early in the curriculum, and in courses designed for students majoring in other areas. Students in various courses could pursue other aspects of these same molecules including odor and cooling properties, and green chemistry approaches to synthesizing menthols.
Molecular Models of Lycopene and Other Carotenoids   
(Interactive Simulation (1))
Over the past decade or so the phrase emerging research suggests has entered the argot of advertising, and that phrase has been applied to this month's Featured Molecule, lycopene, particularly with regard to potential health benefits of tomatoes. The paper by Jie Zhu, Mingjie Zhang, and Qingwei Liu (1) describes an extraction and purification of lycopene from tomato paste using an emulsion rather than the traditional solvent-based extraction. Lycopene is a member of the family of molecules called carotenoids, the most familiar of which is beta-carotene. This family of natural products includes more than 500 members that have been isolated and whose structures have been determined. Professor Hanspeter Pfander's research group at the University of Bern maintains a Web site with a significant amount of information on carotenoid structure, synthesis, and activity (2). Structurally one can think of carotenoids as consisting of three segments, a relatively rigid conjugated central portion with end groups. The end groups are, in general, flexible with respect to rotation about the bond connecting them to the central portion. For example, in beta-carotene, the dependence of total energy on the dihedral angle shown in Figure 1, displays a very broad range of essentially isoenergetic conformations (Figure 2). The energies shown in Figure 2 were calculated at the PM3 level using Hyperchem 7.5 (3). Calculations at the HF/631-G(d,p) level, with many fewer data points, show a similar trend. Many of the health benefits derived from various carotenoids are attributed to their antioxidant activities. Carotenoids react with singlet-oxygen in a physical, diffusion-controlled, quenching process that results in ground state triplet-oxygen and, following a non-radiative relaxation, ground state carotenoid. Of the various carotenoids that have been studied, lycopene and beta-carotene show the greatest quenching rate constants (4). The carotenoids provide us with countless explorations by students and teachers looking for connections between fundamental chemical concepts and real-world applications. Structure, reactivity, chemical synthesis, biosynthesis, and stereochemistry are just a few of the concepts involved in understanding the manifest important roles that these molecules play.
Molecular Models of Antioxidants and Radicals   
(Interactive Simulation (1))
This month's featured molecules come from the paper by John M. Berger, Roshniben J. Rana, Hira Javeed, Iqra Javeed, and Sandi L. Schulien (1) describing the use of DPPH to measure antioxidant activity. DPPH was one of the featured molecules in September 2007 (2) and the basics of antioxidant activity were introduced in last month's column (3). In addition, some of the other molecules in the paper are already in the featured molecules collection (4). The remaining structures in the Figure 1 and Table 1 of the paper have been added to the collection. All structures have been optimized at the 6-311G(D,P) level. These molecules suggest a number of possible student activities, some reminiscent of previous columns and some new. (R,R,R)-α-tocopherol is one of the molecules in the mixture that goes by the name vitamin E. These molecules differ in the substituents on the benzene ring and on whether or not there are alternating double bonds in the phytyl tail. In (R,R,R)-α-tocopherol the R's refer to the three chiral carbon atoms in tail while α refers to the substituents on the ring. (R,R,R)-α-Tocopherol is the form found in nature. An interesting literature problem would be to have students learn more about the vitamin E mixture and the differing antioxidant activity of the various constituents. Additionally they could be asked to explore the difference between the word natural as used by a chemist, and "natural" as used on vitamin E supplements. Can students find regulations governing the use of the term "natural"? Can they suggest alternative legislation, and defend their ideas? If students read about vitamin C they will discover that only L-ascorbic acid is useful in the body. It would be interesting to extend the experiment described in the Berger et al. paper (1) to include D-ascorbic acid. How do the antioxidant abilities of the enantiomers, as determined by reaction with DPPH compare? Is this consistent with the behavior in the body? Why or why not? Berger et al. mention two other stable neutral radicals, TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) and Fremy's salt. In a reversal from the use of stable radicals to measure antioxidant properties, these two molecules have proven to be very versatile oxidation catalysts in organic synthesis, and would make a rich source of research papers for students in undergraduate organic courses.
Molecular Models of Products and Reactants from Suzuki and Heck Syntheses   
(Interactive Simulation (1))
Our Featured Molecules this month come from the paper by Evangelos Aktoudianakis, Elton Chan, Amanda R. Edward, Isabel Jarosz, Vicki Lee, Leo Mui, Sonya S. Thatipamala, and Andrew P. Dicks (1), in which they describe the synthesis of 4-phenylphenol using an aqueous-based Suzuki reaction. The authors describe the various ways in which this reaction addresses concerns of green chemistry, and point out that their product bears structural similarity to two non-steroidal anti-inflammatory drugs (NSAIDs), felbinac and diflunisal. A number of molecules from this paper and its online supplemental material have been added to the Featured Molecules collection. Students will first notice that the aromatic rings in the molecules based on a biphenyl backbone are non-planar, as is the case in biphenyl. If they look carefully at diflunisal, they will notice that the carbon atoms are in a different chemical environment. One way in which to see the effect of these differing environments is to examine the effect of atom charge on the energies of the carbon 1s orbitals. Figure 1 shows this effect using charges and energies from an HF/631-G(d) calculation. A reasonable question to ask students would be to assign each of the data points to the appropriate carbon atom. As an extension of this exercise students could produce similar plots using different computational schemes. Are the results the same; are they parallel. This would be a useful problem when dealing with the tricky question of exactly what is meant by atom charge in electronic structure calculations. Students with more expertise in organic chemistry could explore extending the synthesis of 4-phenylphenol to produce more complex bi- and polyphenyl-based drugs. This may well be the first time that they have seen coupling reactions such as the Suzuki and Heck reactions. Students in introductory and non-science-major courses might well find the NSAIDs to be an interesting group of molecules, and could be asked to find information on the variety of molecules that display the anti-inflammatory properties associated with NSAIDs. Do they find structural similarities? Are there various classes of NSAIDs? Are they familiar with any of these molecules? Have they taken any NSAIDs? If so, for what reason? Is there any controversy about any of the NSAIDs? As with all of the molecules in the Featured Molecules collections, those added this month provide us with a number of ways of showing students the practical relevance of what they sometime see only as lines on a page. Molecules do matter.
Molecular Models of Reactants and Products from an Asymmetric Synthesis of a Chiral Carboxylic Acid   
(Interactive Simulation (1))
Our JCE Featured Molecules for this month come from the paper by Thomas E. Smith, David P. Richardson, George A. Truran, Katherine Belecki, and Megumi Onishi (1). The authors describe the use of a chiral auxiliary, 4-benzyl-2-oxazolidinone, in the synthesis of a chiral carboxylic acid. The majority of the molecules used in the experiment, together with several of the pharmaceuticals mentioned in the paper, have been added to our molecule collection. In many instances multiple enantiomeric and diastereomeric forms of the molecules have been included. This experiment could easily be extended to incorporate various aspects of computation for use in an advanced organic or integrated laboratory. Here are some possible exercises using the R and S forms of the 4-benzyl-2-oxazolidinone as the authors point out that both forms are available commercially. Calculation of the optimized structures and energies of the enantiomers at the HF/631-G(d) level using Gaussian03 (2) produces the results shown in Table 1. Evaluation of the vibrational frequencies results in no imaginary frequencies and the 66 real frequencies are identical for the two forms. Examination of the computed IR spectra also shows them to be identical. Additionally, the Raman and NMR spectra can be calculated for the enantiomers and compared to experimental values and spectral patterns. A tool that is becoming increasingly important for assigning absolute configuration is vibrational circular dichroism (VCD). Although the vibrational spectra of an enantiomeric pair are identical, the VCD spectra show opposite signs, as shown in Figure 1. One can imagine a synthesis, using an unknown enantiomer of the chiral auxiliary, followed by calculations of the electronic and vibrational properties of all of the intermediates and the product, and determination of absolute configuration of reactants and products by comparison of experimental and computed VCD spectra. Using a viewer capable of displaying two molecules that can be moved independently, students could more easily visualize the origin of the enantiomeric preference in the reaction between the chelated enolate and allyl iodide.
Molecular Models of Real and Mock Illicit Drugs from a Forensic Chemistry Activity   
(Interactive Simulation (1))
The Featured Molecules for this month come from the paper by Shawn Hasan, Deborah Bromfield-Lee, Maria T. Oliver-Hoyo, and Jose A. Cintron-Maldonado (1). The authors describe a forensic chemistry exercise in which model compounds are used to simulate the behavior of various drugs in a series of chemical tests. Structures of a number of the chemicals used in the experiment, and several of the drugs they are serving as proxy for, have been added to the molecule collection. Other substances used in the experiment are already part of the collection, including caffeine and aspirin. One structure that may be both intriguing and confusing to students is that of chlorpromazine (Thorazine, Figure 1). A majority of students might well expect the ring portion of the molecule to show a planar structure. This is not what is found from calculations at the HF/6311++G(d,p) level in both the gas phase and in water. Instead, the three rings are in a V-like formation with a deformation of approximately 50 degrees from planarity. Tracking down the source of this non-planarity would be a useful computational exercise. Does it arise from the presence of the alkyl chain (steric effect), from the chloro group (electronic effect), or from electronic effects involving the elements of the heterocyclic ring? As a starting point to addressing these questions, students could be introduced to the use of model compounds in computation. One such compound would be the parent ring system phenothiazine (Figure 2). That molecule contains neither a chloro substituent nor an extended alkyl group. Is it also found to be non-planar? Is the deformation angle the same, larger, or smaller than in chlorpromazine? Does the addition of chloro group to phenothiazene change the angle significantly? What about the addition of an alkyl group? If the model compound is forced to be planar are all of the vibrational frequencies real (positive)? If not, what type of deformation is suggested by the imaginary (negative) vibration?
Collection of Chiral Drug, Pesticide, and Fragrance Molecular Models   
(Interactive Simulation (1))
The article by Mannschreck, Kiessewetter, and von Angerer on the differential interactions between enantiomers and biological receptors (1) is the source for this month's Featured Molecules. Included in the molecule collection are all of the molecules described in the paper. In many instances we have included structures of multiple optical isomers of the same molecule so that students can not only see the forms that are active, but those that are less active, inactive, or act in an undesirable manner. These molecules will serve as good practice in determining optical configurations, and will also introduce additional forms of isomerism that students may be less familiar with than they are with R and S. Since multiple enantiomers and diastereomers are provided, students may use these molecules, together with an appropriate computational package, to verify that enantiomers have the same energy while diastereomers do not. The tuberculosis drug ethambutol provides an interesting case as both nitrogen atoms are also chiral as well as the two chiral carbon atoms. A calculation on a given structure will include the effect of that nitrogen chirality, although nitrogen inversion is expected to be quite rapid in this molecule. The conformations for the ethambutol molecules that are included here consider all four chiral atoms and are of the form (CNNC). A reasonable computational exercise would be to find the transition state for nitrogen inversion and the barrier height for that process. The supplemental material that is included with the featured article (1) includes a number of molecules that we will add to the collection as time permits. The result, including enantiomers and diastereomers, will be well over 200 additional molecules. A notice will appear in the JCE Featured Molecules column when this new set of molecules is available in JCE Online.
Molecular Models of Dyes   
(Interactive Simulation (1))
The paper on the synthesis of several dyes by James V. McCullagh and Kelly A. Daggett (1) provides us with the JCE Featured Molecules for this month. The authors mention various applications of these dyes, ranging from commercial dyeing to techniques for determining the course of complex biochemical processes. One of the reaction products, rhodamine B, is a member of a family of molecules that are widely used as tunable laser dyes. In this application, the rhodamines are most commonly encountered in a cationic form, rather than in the neutral form shown in the paper. In the cations, the carboxyl group is no longer part of a ring system. Several different members of the rhodamine family are included in the molecule collection because substituents have a marked effect on the effective lasing range of a given dye. Additionally, the solvent and the excitation source also influence the lasing range (2). Students can learn more about the relationship between structure, absorption and emission properties, and lasing ranges of various dyes by consulting ref 2 and from PhotochemCAD, Jonathan Lindsey's free application (3).
Molecular Models of Rosmarinic Acid and DPPH   
(Interactive Simulation (1))
The paper by Canelas and da Costa (1) introduces students to the antioxidant rosmarinic acid, and its interaction with the free radical DPPH. Those two molecules are the featured species this month. The original paper shows the 2-dimensional structure of the cis isomer of rosmarinic acid, although the trans isomer exhibits very similar antioxidant properties. Calculations at the DFT/B3LYP 631-G(d) level show that the trans isomer is more stable than the cis isomer in the gas phase, a situation that is expected to carry over into solution. Many antioxidants are phenols, and rosmarinic acid has four such groups available for radical formation. A DFT study by Cao et al. (2) examines the relative stabilities of the radicals formed from loss of each of the phenolic hydrogens. That paper focuses on the trans isomer, and a useful student project would be to repeat the calculations with the cis isomer. An HPLC separation of the isomers of rosmarinic acid has been published (3), and might well lead to an extension of the experiment described in ref 1 in which relative antioxidant efficiencies of the two isomers could be evaluated. DPPH has been used extensively as a standard for determining antioxidant activity. An examination of the molecular orbital occupied by the lone electron shows significant delocalization, providing a partial explanation for the stability of the neutral radical. Our gas phase structure for DPPH, also at the DFT/B3LYP 631-G(d) level, is quite consistent with several crystal structures on DPPH and DPPH in the presence of another species (4).
Molecular Models of DAPI   
(Interactive Simulation (1))
This month's Featured Molecule is DAPI (4′,6-diamidino-2-phenylindole), from the paper by Eamonn F. Healy (1). The utility of DAPI is a consequence of its being a minor-groove binder to DNA. A crystal structure of DAPI binding to the minor groove of a synthetic DNA has been determined, and the structure file made available through the RCSB Protein Data Bank (2, 3). That structure is also included in the Featured Molecules Collection, with the water molecules removed for the sake of clarity. For many students this may be their first encounter with the binding of small molecules to DNA. Another example of such binding is the intercalation of the antibiotic actinomycin into DNA. The Department of Biology at the University of Hamburg maintains an excellent Web site showing both crystal and NMR structures of actinomycin intercalation (4). Observant students will also note in the structure of DAPI a theme that has appeared several times in our Featured Molecules, and that is the non-planarity of adjacent delocalized ring systems. In DAPI, it is a five-membered ring adjacent to a six-membered ring, and the observed departure from planarity is less than that in biphenyl. Students might be asked to explain that difference.
Molecular Models of Resveratrol   
(Interactive Simulation (1))
The featured molecules this month are from the paper "Resveratrol Photoisomerization: An Integrative Guided-Inquiry Experiment" by Bernard, Gernigon, and Britz-McKibbin exploring trans to cis photoisomerization in resveratrol. Examination of Figure 1 in that paper, where the hydrogen atoms have been omitted, might lead one to conclude that the structures are relatively straightforward. These isomers provide students an excellent opportunity to test their ability to take a two-dimensional representation and envision the three-dimensional structure of the molecule and to consider the competing factors that might lead to the three-dimensional structures being non-planar. The two-dimensional models focus attention on the possibility of extended pi-electron delocalization. Addition of the hydrogen atoms clearly suggests that delocalization will compete with non-bonded H-H repulsions in the cis isomer. Further examination of the trans isomer shows that such non-bonded interactions are, in what one might call a first-order approximation, like those in biphenyl interactions that lead biphenyl to be non-planar in both the gas phase and in a variety of solvents. The backbone of the trans isomer of resveratrol, trans-stilbene, has been the subject of a number of theoretical and experimental investigations (1, 2). In general, Hartree-Fock calculations predict a non-planar geometry for this molecule while Density Functional Calculations, using the same basis sets, predict an essentially planar structure. Spectroscopic evidence supports a temperature-dependent structure for trans-stilbene with the molecule being planar at low temperature and non-planar at high temperatures. Our calculations on trans-resveratrol produce similar results. Hartree-Fock calculations using the 6-31G** (6- 31G(d,p)) basis set predict a dihedral angle of approximately 24 degrees between each ring and the central carbon-carbon double bond. This result is consistent with the reported value of 23 degrees using the 6-31G* basis set. We also find that DFT calculations using the B3LYP functional and the 6- 31G** basis set, lead to a planar configuration. We include several versions of trans-stilbene and trans-resveratrol in the molecule collection so that students can explore these structural questions in more detail. For each molecule, structures obtained from PM3, HF(6-31G**), and DFT(B3LYP/6-31G**) calculations are included, as well as planar and non-planar structures of biphenyl. Measurement of the various bond and torsion angles using Jmol will help students develop a sense of the distance dependence of the non-bonded interactions and their importance in determining the actual structure. They might also wish to consider what additional degree(s) of freedom resveratrol and stilbene have that biphenyl does not, allowing the trans-form of the former molecules to remain planar under certain conditions, while minimizing the effect of the non-bonded repulsions.
Molecular Models of Ruthenium(II) Organometallic Complexes   
(Interactive Simulation (1))
The featured molecules for this month come from the paper "Experiments in Thermodynamics and Kinetics of Phosphine Substitution in (p-Cymene)RuCl2(PR3)" by Ozerov, Moura, and Hoffman in which they study the reactions of a number of "piano stool" complexes of ruthenium(II). The synthesis of compound 2a offers students an alternative to the preparation of ferrocene if they are only preparing one metal-arene complex, and the use of the (p-cymene)RuCl2 dimer as a starting material introduces them to a compound that has become important for the synthesis of a number of ruthenium catalysts. Two structures are found for the dimer in the gas phase, one with the chlorides cis to one another and a more stable form with the chlorides trans. DFT calculations using the LanL2MB basis set and the B3LYP functional in Gaussian 03 (1) show the trans form to be about 90 kJ/mol more stable than the cis form. The structures of the trans form of the dimer and of compound 2a are presented in 2 formats with bonds from the ruthenium ion to all of the carbons in the aryl ring and with a single line to a ghost atom in the center of the ring. These are the two common ways of representing such structures but students should be made aware that the overall coordination about the ruthenium in both the dimer and in compound 2a is octahedral, and should look at the structures to convince themselves of that fact. It is also instructive to look at compound 2a, and the other piano stool complexes that are made in the paper, to see how deceptive representation of the triphenylphosphine moiety as PR3 is in terms of the stereochemical bulk of that group.
Electrostatics Attraction (GCMP)   
(Interactive Simulation, Software (1))
Electrostatics Attraction: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will correlate molecular polarity with the attraction of liquids to a charged rod. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Water #2 (GCMP)   
(Interactive Simulation, Software (1))
Water #2: this is a resource in the collection "General Chemistry Multimedia Problems". Isotopes are forms of the same element composed of atoms that have different numbers of neutrons. In this problem we will begin by observing the properties of water containing two isotopes of hydrogen. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Water #1 (GCMP)   
(Interactive Simulation, Software (1))
Water #1: this is a resource in the collection "General Chemistry Multimedia Problems". Isotopes are forms of the same element composed of atoms that have different numbers of neutrons. In this problem we will begin by observing the properties of water containing two isotopes of hydrogen. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Two Solids (GCMP)   
(Interactive Simulation, Software (1))
Two Solids: this is a resource in the collection "General Chemistry Multimedia Problems". When two solids barium hydroxide octahydrate, Ba(OH)2. 8H2O and ammonium thiocyanate, NH4SCN are mixed, they react. We will explore the thermodynamics of the reaction. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Two Balloons (GCMP)   
(Interactive Simulation, Software (1))
Two Balloons: this is a resource in the collection "General Chemistry Multimedia Problems". In the Two Balloons video, the left flask contains some water and the right flask contains only air. What do you see when balloons are fastened to the mouths of the hot flasks? General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Strong Acids (GCMP)   
(Interactive Simulation, Software (1))
Strong Acids: this is a resource in the collection "General Chemistry Multimedia Problems". This problem will explore the properties of common strong acids. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Steam (GCMP)   
(Interactive Simulation, Software (1))
Steam: this is a resource in the collection "General Chemistry Multimedia Problems". We observe two videos of steam produced by boiling water. The steam is channeled through a copper coil which will be heated. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Phlogiston (GCMP)   
(Interactive Simulation, Software (1))
Phlogiston: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will think back to the last half of the 18th century when modern chemistry was beginning to take place. One of the major problems occupying chemists at the time was combustion. The dominant theory of combustion in the mid-18th century involved a substance called "phlogiston." General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Paramagnetism (GCMP)   
(Interactive Simulation, Software (1))
Paramagnetism: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will begin by observing the magnetism of three manganese compounds. These compounds have been placed in capsules, which will be pulled toward a magnet if the compound is paramagnetic. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Oxides (GCMP)   
(Interactive Simulation, Software (1))
Oxides: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will explore the properties of the oxides of a few elements. We will add samples of the oxides to universal indicator solution and learn about the acid-base character of the oxides. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
NO and O2 #3 (GCMP)   
(Interactive Simulation, Software (1))
NO and O2 #3: this is a resource in the collection "General Chemistry Multimedia Problems". NO and O2 and the product of the corresponding reaction are three gases which have different solubilities in water. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
NO and O2 #2 (GCMP)   
(Interactive Simulation, Software (1))
NO and O2 #2: this is a resource in the collection "General Chemistry Multimedia Problems". NO and O2 and the product of the corresponding reaction are three gases which have different solubilities in water. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
NO and O2 (GCMP)   
(Interactive Simulation, Software (1))
NO and O2: this is a resource in the collection "General Chemistry Multimedia Problems". NO and O2 and the product of the corresponding reaction are three gases which have different solubilities in water. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Nitrogen Oxides (GCMP)   
(Interactive Simulation, Software (1))
Nitrogen Oxides: this is a resource in the collection "General Chemistry Multimedia Problems". Two of the most important nitrogen oxides, N2O4 and NO2, are in equilibrium with each other. We are interested in how this equilibrium shifts with temperature. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Metals 2 (GCMP)   
(Interactive Simulation, Software (1))
Reactions of Metals 2: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will observe the reactions of different metals (Zn, Ni, Mn, Fe) with iodine. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Metals 1 (GCMP)   
(Interactive Simulation, Software (1))
Reactions of Metals 1: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will observe the reactions of different metals (Zn, Ni, Mn, Fe) with iodine. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Hexane 2 (GCMP)   
(Interactive Simulation, Software (1))
Hexane 2: this is a resource in the collection "General Chemistry Multimedia Problems". Hexane, a liquid hydrocarbon with the formula C6H14, burns when ignited in the presence of oxygen. In this problem we will observe videos of this combustion reaction. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Hexane 1 (GCMP)   
(Interactive Simulation, Software (1))
Hexane 1: this is a resource in the collection "General Chemistry Multimedia Problems". Hexane, a liquid hydrocarbon with the formula C6H14, burns when ignited in the presence of oxygen. In this problem we will observe videos of this combustion reaction. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Halogens and Halides (GCMP)   
(Interactive Simulation, Software (1))
Halogens and Halides: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will study the oxidation-reduction reactions between the halogens and the halide ions. The halogens and halides will be dissolved in water and hexane. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Floating Squares (GCMP)   
(Interactive Simulation, Software (1))
Floating Squares: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will coat a piece of notecard with graphite (from pencil lead). We then will float the piece in two beakers containing water and a second solvent. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Fireworks (GCMP)   
(Interactive Simulation, Software (1))
Fireworks: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will study the colors produced by metal salts in flames. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Electrolisis 3 (GCMP)   
(Interactive Simulation, Software (1))
Electrolisis of Water #3: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will contrast the electrolysis of water with boiling. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Electrolisis 2 (GCMP)   
(Interactive Simulation, Software (1))
Electrolisis of Water #2: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will contrast the electrolysis of water with boiling. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Electrolisis 1 (GCMP)   
(Interactive Simulation, Software (1))
Electrolisis of Water #1: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will contrast the electrolysis of water with boiling. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Drinking Bird (GCMP)   
(Interactive Simulation, Software (1))
Drinking Bird: this is a resource in the collection "General Chemistry Multimedia Problems". The drinking bird's felt-covered head dips into the beaker of water as it bobs up and down. The tube goes from the bottom of the body to its head. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Disorder (GCMP)   
(Interactive Simulation, Software (1))
Disorder: this is a resource in the collection "General Chemistry Multimedia Problems". A spontaneous change is one that has a natural tendency to occur without needing to be driven by an external influence. This problem will explore the influence of entropy, a measure of disorder, on the spontaneity of a few processes. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Chromate-Dichromate (GCMP)   
(Interactive Simulation, Software (1))
Chromate/Dichromate: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will study shifts in the equilibrium between chromate and dichromate. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Burning Magnesium (GCMP)   
(Interactive Simulation, Software (1))
Burning Magnesium: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will look at the reactions of two elements with oxygen in air. We will begin by observing the reaction of magnesium metal with oxygen when the metal is heated in air. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Cannon (GCMP)   
(Interactive Simulation, Software (1))
H2 and Cl2 cannon: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we observe the reaction of hydrogen and chlorine and explore some related reactions. The reaction involves a radical mechanism initiated by light. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Ammonia (GCMP)   
(Interactive Simulation, Software (1))
Ammonia fountain: this is a resource in the collection "General Chemistry Multimedia Problems". In an ammonia fountain, a flask is filled with ammonia gas. A tube from the flask extends into a pan of water that contains phenolphthalein. When a rubber bulb full of water is squeezed, the water squirts into the flask. Water from the pan then is pushed into the flask and the indicator changes color. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Acids and Salts (GCMP)   
(Interactive Simulation, Software (1))
Acids and Salts: this is a resource in the collection "General Chemistry Multimedia Problems". This problem will explore a few properties of common acids and their salts. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
Acids (GCMP)   
(Interactive Simulation, Software (1))
Acids: this is a resource in the collection "General Chemistry Multimedia Problems". We will observe the reaction of sodium bicarbonate with three acid solutions. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.
A Window on the Solid State   
(Instructional Strategy, Interactive Simulation (1))
A Window on the Solid State helps students understand and instructors present the structural features of solids. Parts I and II were published previously by JCE Software (1) and Macintosh versions of Parts I and II are also available (2). Parts I and II have been updated to include improvements in art and minor changes in logic. Parts III and IV expand the collection to include the structures of simple ionic solids using the visual effects available in an interactive computer medium. The package provides a tour of the structures commonly used to introduce features of the solid state.
Atomic Radius Worksheet   
(Instructional Material (1))
In this course you can find worksheets to use in your classes or to assign as homework assignments that teach various concepts about the periodic table using the free ChemEd DL resource, the Periodic Table Live!(PTL!).
Periodic Table Live! Tutorial (part I)   
(Instructional Material (1))
Look here for a tutorial to guide you through the use of the Periodic Table Live! It is in the form of 2 power point files which you can download. We recommend opening up your web browser and trying things out as the power point suggests.
Questions the Periodic Table Live! can help answer   
(Instructional Material (1))
List of questions PTL can help students answer.
General Exploration Worksheet   
(Instructional Material (1))
In this course you can find worksheets to use in your classes or to assign as homework assignments that teach various concepts about the periodic table using the free ChemEd DL resource, the Periodic Table Live!(PTL!).
Ionization Energy Worksheet   
(Instructional Material (1))
In this course you can find worksheets to use in your classes or to assign as homework assignments that teach various concepts about the periodic table using the free ChemEd DL resource, the Periodic Table Live!(PTL!).
Electron Affinity Worksheet   
(Instructional Material (1))
In this course you can find worksheets to use in your classes or to assign as homework assignments that teach various concepts about the periodic table using the free ChemEd DL resource, the Periodic Table Live!(PTL!).
Carbon Worksheet   
(Instructional Material (1))
In this course you can find worksheets to use in your classes or to assign as homework assignments that teach various concepts about the periodic table using the free ChemEd DL resource, the Periodic Table Live!(PTL!).
Electronegativity Worksheet   
(Instructional Material (1))
In this course you can find worksheets to use in your classes or to assign as homework assignments that teach various concepts about the periodic table using the free ChemEd DL resource, the Periodic Table Live!(PTL!).
Stereochemistry Tutorial   
(Instructional Material (1))
Master the concepts organic stereochemistry with this interactive tutorial. It includes definitions, different three dimensional representations, assigning priorities to stereocenters, and determining the stereochemical relationship between molecules. Each section is followed by a question set that tests knowledge and understanding.
Titration (ChemPages Lab)   
(Instructional Material (1))
Titration: this is a resource in the collection "ChemPages Laboratory Resources". A titration is a laboratory procedure for quantitative analysis. Titrametric analysis is used to determine the concentration of an analyte in solution, the stoichiometry of a reaction, the number of electrons gained or accepted in a redox reaction and the solubility products. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Acids and Bases (Netorials)   
(Instructional Material (1))
Acids and Bases: this is a resource in the collection "Netorials". In this module there is an introduction to the chemical properties of acids and bases. Afterwards, the sections include topics such as Molecular Structures of Acids and Bases, Ionization constants, properties of salts, buffers and Lewis theory of Acids and Bases. The Netorials cover selected topics in first-year chemistry including: Chemical Reactions, Stoichiometry, Thermodynamics, Intermolecular Forces, Acids & Bases, Biomolecules, and Electrochemistry.
Intermolecular Forces (Netorials)   
(Instructional Material (1))
Intermolecular Forces: this is a resource in the collection "Netorials". In this resource there is a review of Lewis structures, molecular geometry, electronegativity, or molecular polarity. After that, you can learn about the forces of attraction that exist between molecules. This module explores London forces and dipole-dipole forces (including hydrogen bonds). The Netorials cover selected topics in first-year chemistry including: Chemical Reactions, Stoichiometry, Thermodynamics, Intermolecular Forces, Acids & Bases, Biomolecules, and Electrochemistry.
Stoichiometry (Netorials)   
(Instructional Material (1))
Stoichiometry: this is a resource in the collection "Netorials". Stoichiometry shows how to balance chemical equations, deal with limiting reactants, computing yelds, working with molarity and different concentrations as well as the use of stoichiometry principles in the chemical analysis of a mixture. The Netorials cover selected topics in first-year chemistry including: Chemical Reactions, Stoichiometry, Thermodynamics, Intermolecular Forces, Acids & Bases, Biomolecules, and Electrochemistry.
Chemical Reactions (Netorials)   
(Instructional Material (1))
Chemical Reactions: this is a resource in the collection "Netorials". The Netorials cover selected topics in first-year chemistry including: Chemical Reactions, Stoichiometry, Thermodynamics, Intermolecular Forces, Acids & Bases, Biomolecules, and Electrochemistry.
Chromatography, Gas (ChemPages Lab)   
(Instructional Material (1))
Chromatography, Gas: this is a resource in the collection "ChemPages Laboratory Resources". Gas chromatography is a method for separating the components of a solution and measuring their relative quantities. It is a useful technique for chemicals that do not decompose at high temperatures and when a very small quantity of sample (micrograms) is available. The use of gas chromatography is limited by the decomposition temperature of the components of the mixture and the composition of the column. Most columns cannot withstand temperatures greater than 250-350 °C. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Chart Recorder (ChemPages Lab)   
(Instructional Material (1))
Chart Recorder: this is a resource in the collection "ChemPages Laboratory Resources". A chart recorder can be used to record data versus time. Chart recorders are commonly used to record chromatographic data. (Though computer data acquisition is increasingly more common.) The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Centrifuge (ChemPages Lab)   
(Instructional Material (1))
Centrifuge: this is a resource in the collection "ChemPages Laboratory Resources". The centrifuge is used to separate a solid from a solution quickly. A centrifuge is used for small-scale separations; typically the volume is less than 5 mL. Larger volumes of mixtures can be separated by filtration. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Buret (ChemPages Lab)   
(Instructional Material (1))
Buret: this is a resource in the collection "ChemPages Laboratory Resources". A buret is a glass tube with graduations that can be used to determine the volume of solution added to a receiving vessel. The buret is designed to accurately deliver between 30 and 50 mL of a solution. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Bulb 3-Way (ChemPages Lab)   
(Instructional Material (1))
Bulb 3-Way: this is a resource in the collection "ChemPages Laboratory Resources". A three-way pipet bulb is used to draw a liquid into any type of pipet. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Bulb Standard (ChemPages Lab)   
(Instructional Material (1))
Bulb Standard: this is a resource in the collection "ChemPages Laboratory Resources". A standard pipet bulb is used to draw a liquid into any type of pipet. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Barometer (ChemPages Lab)   
(Instructional Material (1))
Barometer: this is a resource in the collection "ChemPages Laboratory Resources". A mercury barometer is used to measure atmospheric pressure. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Balance (ChemPages Lab)   
(Instructional Material (1))
Balance: this is a resource in the collection "ChemPages Laboratory Resources". A laboratory balance is used to measure the mass of reagents or laboratory equipment. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Thermometer (ChemPages Lab)   
(Instructional Material (1))
Thermometer: this is a resource in the collection "ChemPages Laboratory Resources". A thermometer is used to measure the temperature of solids, liquids, or gases. A thermometer contains a liquid (usually mercury or an alcohol solution) in a reservoir whose volume is linearly dependent on the temperature (as the temperature increases, the volume increases). The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Spectroscope, Hand-Held (ChemPages Lab)   
(Instructional Material (1))
Spectroscope, Hand-Held: this is a resource in the collection "ChemPages Laboratory Resources". A hand-held spectroscope contains a diffraction grating that separates electromagnetic radiation into its component wavelengths. The spectroscope can observe either absorption or emission spectra. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Spectrometer, Spectronic 20 (ChemPages Lab)   
(Instructional Material (1))
Spectrometer, Spectronic 20?: this is a resource in the collection "ChemPages Laboratory Resources". The Spectronic 20? is used to measure the absorbance (or transmittance) of solutions. A Spectronic 20? is capable of measuring % transmittance and absorbance over the range of 340 to 950 nm (the range 600 to 950 nm requires a special infrared filter and a different lamp). The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Spectrophotometer, Scanning UV-Visible (ChemPages Lab)   
(Instructional Material (1))
Spectrophotometer, Scanning UV/Visible: this is a resource in the collection "ChemPages Laboratory Resources". A scanning ultraviolet/visible (UV/Vis) spectrophotometer operates on the same principles as a Spectronic 20?. They both can be used for qualitative and quantitative analysis. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Separatory Funnel (ChemPages Lab)   
(Instructional Material (1))
Separatory Funnel and Extraction: this is a resource in the collection "ChemPages Laboratory Resources". A separatory funnel is useful for performing extractions. Extraction is one way of purifying a substance. In an extraction, a solute is transferred from one solvent to another. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Scales (ChemPages Lab)   
(Instructional Material (1))
Scales: this is a resource in the collection "ChemPages Laboratory Resources". Correctly reading a scale is a skill that is important to master. The Spectronic 20?, spectroscope, pipet, buret, graduated cylinder, and many other instruments and devices utlilize scales that must be read properly for successful laboratory work. The procedures outlined in this module should be followed for reading any scalar quantity in the laboratory. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Pouring (ChemPages Lab)   
(Instructional Material (1))
Pouring: this is a resource in the collection "ChemPages Laboratory Resources". Pouring is a way to transfer material from one container to another. Chemical containers have either screw-top lids or glass stoppers. When removing a screw-top lid be sure to set it down on the bench, top side down. Glass stoppers should be held during the transfer of chemicals. Remember to replace the lid after you are done. Careful handling of lids and stoppers will help to prevent contamination. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Pipet, Volumetric (ChemPages Lab)   
(Instructional Material (1))
Pipet, Volumetric: this is a resource in the collection "ChemPages Laboratory Resources". Pipetting involves drawing a liquid into a pipet and allowing liquid to drain from the pipet in a controlled manner. Pipetting is used to quantitatively transfer a liquid from one container to another. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Mohr Pipet (ChemPages Lab)   
(Instructional Material (1))
Mohr Pipet: this is a resource in the collection "ChemPages Laboratory Resources". A Mohr Pipet is a graduated pipet that is designd to deliver small portions of a liquid or solution. These portions are determined by recording the difference between the initial and final volume readings. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Pipettor, Digital (ChemPages Lab)   
(Instructional Material (1))
Pipettor, Digital: this is a resource in the collection "ChemPages Laboratory Resources". Digital pipettors deliver liquids in volumes from 1 mL to 1µL or less. They are sometimes called "micropipets", "Eppendorf pipets" or simply "Eppendorfs" after one of the more prevalent brands. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
pH Paper (ChemPages Lab)   
(Instructional Material (1))
pH Paper: this is a resource in the collection "ChemPages Laboratory Resources". The approximate pH of a solution can be determined by placing a drop of the solution on a piece of indicator paper. Two types of pH paper are commonly used: litmus paper and universal (Alkacid) paper. The type of pH paper used is dependent on the type of measurement and degree of accuracy required. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
pH Meter (ChemPages Lab)   
(Instructional Material (1))
pH Meter: this is a resource in the collection "ChemPages Laboratory Resources". A pH meter represents the hydrogen ion concentration in pH units. A pH meter consists of a glass electrode and a read out screen. The glass electrode is made of very thin glass that establishes and measures the electrical potential difference between the analyte solution (the solution to be measured) and an internal reference. The electrical potential is then converted into a pH reading for the sample. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Mixing (ChemPages Lab)   
(Instructional Material (1))
Mixing: this is a resource in the collection "ChemPages Laboratory Resources". Mixing usually produces and maintains a uniform, homgeneous solution. Mixing two solutions often initiates a reaction by bringing substances into contact. Mixing techniques depend on the volume of the solution, the viscosity of the solution, the type of substances to be mixed, and the equipment available. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Melting Points (ChemPages Lab)   
(Instructional Material (1))
Melting Points: this is a resource in the collection "ChemPages Laboratory Resources". The melting point is a characteristic property of a substance. It can be used for sample identification and purity determination. The melting point is observed by slowly heating a sample and observing the temperature when the sample has changed from a solid to a liquid. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Hot Plate-Magnetic Stirrer (ChemPages Lab)   
(Instructional Material (1))
Hot Plate/Magnetic Stirrer: this is a resource in the collection "ChemPages Laboratory Resources". The hotplate/magnetic stirrer is a single device that can heat liquids and stir them with a magnetic stir bar. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Graduated Cylinder (ChemPages Lab)   
(Instructional Material (1))
Graduated Cylinder: this is a resource in the collection "ChemPages Laboratory Resources". Graduated cylinders are used to measure the volume of liquid samples and are available in many different sizes. The measurement accuracy of a graduated cylinder is rather poor (may be as much as 10% off) so you must consider the desired accuracy before choosing to use a graduated cylinder. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Gas Burner (ChemPages Lab)   
(Instructional Material (1))
Gas Burner: this is a resource in the collection "ChemPages Laboratory Resources". A gas burner is used to heat non-flammable objects or solutions. It can be used to heat objects to very high temperatures. Temperatures in the hottest region of the burner exceed 1000°C. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Filtration, Vacuum (ChemPages Lab)   
(Instructional Material (1))
Filtration, Vacuum: this is a resource in the collection "ChemPages Laboratory Resources". Filtration is a technique used to separate a solid from a liquid. The solid is separated from the liquid phase by passing the mixture over a filtering media. The mixture can be forced through the filter by either gravity or reduced pressure on one side of the filter (by creating a vacuum). It is possible to separate a solid from a liquid by either technique, however there are advantages to each technique. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Filtration, Gravity (ChemPages Lab)   
(Instructional Material (1))
Filtration, Gravity: this is a resource in the collection "ChemPages Laboratory Resources". Filtration is a technique used to separate a solid from a liquid. The solid is separated from the liquid phase by passing the mixture over a filtering media. The mixture can be forced through the filter by either gravity or reduced pressure on one side of the filter (by creating a vacuum). It is possible to separate a solid from a liquid by either technique, however there are advantages to each technique. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Flask, Volumetric (ChemPages Lab)   
(Instructional Material (1))
Flask, Volumetric: this is a resource in the collection "ChemPages Laboratory Resources". A volumetric flask is used to measure very precisely one specific volume of liquid (100 mL, 250 mL, etc., depending on which flask you use). This flask is used to accurately prepare a solution of known concentration. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Eppendorf Pipet (ChemPages Lab)   
(Instructional Material (1))
Eppendorf Pipet or Digital Pipettor: this is a resource in the collection "ChemPages Laboratory Resources". Digital pipettors deliver liquids in volumes from 1 mL to 1µL or less. They are sometimes called "micropipets", "Eppendorf pipets" or simply "Eppendorfs" after one of the more prevalent brands. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Electrochemical Cells(ChemPages Lab)   
(Instructional Material (1))
Electrochemical Cells: this is a resource in the collection "ChemPages Laboratory Resources". The cell design described in this module includes two solutions connected by salt bridge (piece of string) and two electrodes (metal strips) connected to a voltmeter. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Conductivity Meter (ChemPages Lab)   
(Instructional Material (1))
Conductivity Meter: this is a resource in the collection "ChemPages Laboratory Resources". A conductivity meter is used to measure the conductivities of electrolytic solutions. Electrodes on the device are dipped into a solution, and the solution's electrical conductivity is registered on the display. Electrical conductivity is defined as the transfer of an electric current through a solid or liquid. In electrolytic solutions, the current is carried by ions, as in solutions of salts, acids or bases. Conductivity is inversely proportional to the resistivity of the solution. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Calorimeter, Coffee Cup (ChemPages Lab)   
(Instructional Material (1))
Calorimeter, Coffee Cup: this is a resource in the collection "ChemPages Laboratory Resources". A coffee cup calorimeter is a useful, simple device that can be used to measure the temperature change that accompanies a reaction. A Styrofoam cup is used because it is a good insulator. The cup will absorb (or supply) negligible amounts of heat during most General Chemistry experiments. Thus, any change in temperature is assumed to be due only to the reaction, and the heat transferred in the reaction may be calculated. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Chromatography, Thin Layer (ChemPages Lab)   
(Instructional Material (1))
Chromatography, Thin Layer: this is a resource in the collection "ChemPages Laboratory Resources". Thin layer chromatography (TLC) is a method for identifying substances and testing the purity of compounds. TLC is a useful technique because it is relatively quick and requires small quantities of material. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Chromatography, Paper (ChemPages Lab)   
(Instructional Material (1))
Chromatography, Paper: this is a resource in the collection "ChemPages Laboratory Resources". Paper chromatography is one method for testing the purity of compounds and identifying substances. Paper chromatography is a useful technique because it is relatively quick and requires small quantities of material. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.
Electrochemistry (Netorials)   
(Instructional Material (1))
Electrochemistry: this is a resource in the collection "Netorials". This modules about electrochemistry includes topics such as oxidation-reduction and half reactions, voltaic and electrolytic cells, standard cell potentials and batteries. The Netorials cover selected topics in first-year chemistry including: Chemical Reactions, Stoichiometry, Thermodynamics, Intermolecular Forces, Acids & Bases, Biomolecules, and Electrochemistry.
Biomolecules (Netorials)   
(Instructional Material (1))
Biomolecules: this is a resource in the collection "Netorials". This set of modules will provide you with a descriptive overview of the four major classes of biomolecules found in all living organisms: carbohydrates, lipids, proteins, and nucleic acids. The Netorials cover selected topics in first-year chemistry including: Chemical Reactions, Stoichiometry, Thermodynamics, Intermolecular Forces, Acids & Bases, Biomolecules, and Electrochemistry.
Planet Earth   
(Activity, Instructional Material (9), Test, Assessment Material (6), Instructional Material (3))
ACS Science for Kids activities and tests exploring applications of chemistry on Earth.
Your Body   
(Activity, Instructional Material (6), Test, Assessment Material (4), Instructional Material (1))
ACS Science for Kids activities explore the chemistry of the human body.
Solids, Liquids & Gases   
(Activity, Instructional Material (3), Activity (2), Instructional Material (4), Test, Assessment Material (3))
ACS Science for Kids resources explore the chemical and physical properties of solids, liquids, and gases.