TIGER

Journal Articles: 31 results
The Reaction Quotient Is Unnecessary To Solve Equilibrium Problems  Paul S. Matsumoto
The traditional method to determine the equilibrium concentration of chemicals in a reaction, given the equilibrium constant and the initial concentration of chemicals in the reaction, involves the determination of the reaction quotient. This article will demonstrate that this step may be eliminated; thereby simplifying the algorithm to solve such problems. Such a reduction in the complexity of the algorithm may result in more students successfully being able to solve such problems.
Matsumoto, Paul S. J. Chem. Educ. 2005, 82, 406.
Equilibrium |
Learning Theories |
Chemometrics
Unified Approximations: A New Approach for Monoprotic Weak Acid–Base Equilibria  Harry L. Pardue, Ihab N. Odeh, and Teweldemedhin M. Tesfai
This article describes a new approach to approximate calculations for monoprotic acidbase equilibria in otherwise pure water. The new approach, identified herein as unified approximations, uses a simple decision criterion to select between situations that should be treated as deprotonation and protonation reactions. The remaining treatment takes account of changes in concentrations of conjugate acidbase pairs for all situations and ignores autoprotolysis only for situations for which the analytical concentration of either the conjugate acid or conjugate base will always be larger than zero.
Pardue, Harry L.; Odeh, Ihab N.; Tesfai, Teweldemedhin M. J. Chem. Educ. 2004, 81, 1367.
Acids / Bases |
Equilibrium |
Chemometrics
Reaction to Why Do We Teach Equilibrium Calculations?  Stephen J. Hawkes
"Rigor" in introductory chemistry is often equated with quantitation. Consequently the understanding of chemical reactions and properties is obscured. This was illustrated by Stumpo who asked students to calculate ?E of a reaction, and then on another question on the same test asked a question aimed at its meaning. 77% of the students calculated correctly, but only 24% showed understanding of its meaning. The ability to calculate a number does not measure understanding of the number.
Hawkes, Stephen J. J. Chem. Educ. 2004, 81, 1265.
Equilibrium |
Chemometrics
Reaction to Why Do We Teach Equilibrium Calculations?   Don L. Lewis
A recently published correspondence by Stephen J. Hawkes on teaching equilibrium calculations troubles me. Hawkes dismisses equilibrium calculations as mere algorithms, best deferred until the student can use computer programs. I find it difficult to believe that a computer program enhances understanding. From a chemists point of view, the equilibrium condition is a limit, a limit that (because of stochastic considerations) does not exist. It might be better to make the reaction quotient statement using < or > but the use of those relations is delayed until quantum mechanics.
Lewis, Don L. J. Chem. Educ. 2004, 81, 1265.
Equilibrium |
Chemometrics
Predicting Acid-Base Titration Curves without Calculations  Dennis W. Barnum
In this paper a qualitative and systematic method for sketching titration curves is presented. Even the more complex cases such as salts or polyprotic acids and bases are treated just as easily as simple monoprotic acids. Having students predict the shape of titration curves from known equilibrium constants helps to focus attention on the general principles without distraction by the mathematics.
Barnum, Dennis W. J. Chem. Educ. 1999, 76, 938.
Acids / Bases |
Quantitative Analysis |
Water / Water Chemistry |
Equilibrium |
Learning Theories |
Titration / Volumetric Analysis |
Chemometrics
Do pH in Your Head  Addison Ault
Every aqueous solution has a pH. Two factors determine this pH: the acidic or basic strength of the solute, and its concentration. When you use pKa values to express acidic and basic strength you can easily estimate the approximate pH of many aqueous solutions of acids, bases, and their salts and their buffers.
Ault, Addison. J. Chem. Educ. 1999, 76, 936.
Equilibrium |
Acids / Bases |
Aqueous Solution Chemistry |
Learning Theories |
Chemometrics |
Brønsted-Lowry Acids / Bases
REACT: Exploring Practical Thermodynamic and Equilibrium Calculations  Ramette, Richard W.
Description of REACT software to balance complicated equations; determine thermodynamic data for all reactants and products; calculate changes in free energy, enthalpy, and entropy for a reaction; and find equilibrium conditions for the a reaction.
Ramette, Richard W. J. Chem. Educ. 1995, 72, 240.
Stoichiometry |
Equilibrium |
Thermodynamics |
Chemometrics
Solving equilibria problems with a graphing calculator: A robust method, free of algebra and calculus   Ruch, David K.; Chasteen, T. G.
The method of successive approximations is frequently introduced in freshman chemistry as a means for solving equilibrium equations. However, this often requires an understanding of calculus that is problematic for introductory chemistry students. An alternative method to solving such equations is to use graphic calculators to solve problems graphically.
Ruch, David K.; Chasteen, T. G. J. Chem. Educ. 1993, 70, A184.
Equilibrium |
Chemometrics
Equilibrium Calculator  Allendoerfer, Robert
The equilibrium calculator can calculate the equilibrium concentrations of all reagents in an arbitrary chemical reaction with as many as five reactants and products.
Allendoerfer, Robert J. Chem. Educ. 1993, 70, 126.
Equilibrium |
Chemometrics
On the chemically impossible "other" roots in equilibrium calculations, II  Ludwig, Oliver G.
In a previous paper the author described, using mathematics accessible to students, how an equilibrium calculation leading to a quadratic equation may be shown to have but one "chemical" root. The present work extends this demonstration to some reactions leading to cubic equations.
Ludwig, Oliver G. J. Chem. Educ. 1992, 69, 884.
Chemometrics |
Equilibrium
Solving quadratic equations to the correct number of significant figures  Thomas, Rudolf
Presenting an application of the successive approximations method for solving quadratic or higher order expressions.
Thomas, Rudolf J. Chem. Educ. 1991, 68, 409.
Equilibrium |
Chemometrics
Chemical equilibrium: III. A few math tricks   Gordus, Adon A.
The third article in a series on chemical equilibrium that considers a few math "tricks" useful in equilibrium calculations and approximations.
Gordus, Adon A. J. Chem. Educ. 1991, 68, 291.
Acids / Bases |
Equilibrium |
Chemometrics |
Titration / Volumetric Analysis
Chemical equilibrium: II. Deriving an exact equilibrium equation   Gordus, Adon A.
In this article appearing in a series on chemical equilibrium, authors consider how to derive a completely general equation for any chemical mixture.
Gordus, Adon A. J. Chem. Educ. 1991, 68, 215.
Equilibrium |
Chemometrics
A simple first-order consecutive rate reaction: A different method for its solution   Hughes, Elvin, Jr.
Power series methods should be used whenever possible in chemistry courses.
Hughes, Elvin, Jr. J. Chem. Educ. 1991, 68, 180.
Chemometrics |
Equilibrium
A simple first-order consecutive rate reaction: A different method for its solution   Castillo S., Carlos; Micolta S., Germania
A different way to present an equilibrium equation that appeared previously in this Journal.
Castillo S., Carlos; Micolta S., Germania J. Chem. Educ. 1991, 68, 179.
Chemometrics |
Equilibrium
Solving quadratic equations  Brown, R. J. C.
A better technique than the quadratic equation for chemical equilibria is offered here.
Brown, R. J. C. J. Chem. Educ. 1990, 67, 409.
Chemometrics |
Equilibrium
Chemistry according to ROF (Fee, Richard)  Radcliffe, George; Mackenzie, Norma N.
Two reviews on a software package that consists of 68 programs on 17 disks plus an administrative disk geared toward acquainting students with fundamental chemistry content. For instance, acids and bases, significant figures, electron configuration, chemical structures, bonding, phases, and more.
Radcliffe, George; Mackenzie, Norma N. J. Chem. Educ. 1988, 65, A239.
Chemometrics |
Atomic Properties / Structure |
Equilibrium |
Periodicity / Periodic Table |
Periodicity / Periodic Table |
Stoichiometry |
Physical Properties |
Acids / Bases |
Covalent Bonding
On the chemically impossible "other" roots in equilibrium problems  Ludwig, Oliver G.
Students often have a hard time knowing when to disregard equilibrium roots that are too large or are negative. The author suggests a convincing proof that helps students understand how the relationship between the conceptual and mathematical.
Ludwig, Oliver G. J. Chem. Educ. 1983, 60, 547.
Equilibrium |
Chemometrics
Le Châtelier's principle: the effect of temperature on the solubility of solids in liquids  Brice, L. K.
The purpose of this article is to provide a rigorous but straightforward thermodynamic treatment of the temperature dependence of solubility of solids in liquids that is suitable for presentation at the undergraduate level. The present discussion may suggest how to approach the qualitative aspects of the subject for freshman.
Brice, L. K. J. Chem. Educ. 1983, 60, 387.
Thermodynamics |
Liquids |
Solids |
Chemometrics |
Equilibrium
Small things and large numbers   Rosenberg, Milton H.
Some challenging solubility problems are featured in this note.
Rosenberg, Milton H. J. Chem. Educ. 1981, 58, 962.
Solutions / Solvents |
Equilibrium |
Chemometrics
Dissociation of a weak acid  Ladd, M. F. C.
An earlier treatment of the equilibrium of a weak acid in water gives, for certain ranges of concentration, significantly incorrect results.
Ladd, M. F. C. J. Chem. Educ. 1980, 57, 669.
Acids / Bases |
Aqueous Solution Chemistry |
Equilibrium |
Chemometrics
Intuitive and general approach to acid-base equilibrium calculations  Felty, Wayne L.
The purpose of this paper is to show that the usual intuitive approach used in general chemistry can be readily extended without introduction of additional, sophisticated concepts to give the general, exact expression and to point out the pedagogical advantage of its use.
Felty, Wayne L. J. Chem. Educ. 1978, 55, 576.
Acids / Bases |
Equilibrium |
Chemometrics
Chemical equilibrium: Analogies that separate the mathematics from the chemistry  DeLorenzo, Ronald A.
Demonstrates that the mathematics of chemical equilibria are not difficult, particularly when put in a non-chemical context.
DeLorenzo, Ronald A. J. Chem. Educ. 1977, 54, 676.
Equilibrium |
Chemometrics
A criterion for the simple approximation in dissociation equilibria  Leffler, Amos J.
The author demonstrates quantitative criterion for the assumption that permits the neglect of the amount of dissociated species in the denominator of the dissociation equation.
Leffler, Amos J. J. Chem. Educ. 1976, 53, 460.
Acids / Bases |
Equilibrium |
Chemometrics
Maximizing profits in equilibrium processes  Rish, Ronald J.
Provides the student with an example in which both chemical principles and calculus are applied to a realistic industrial situation where profits are a must.
Rish, Ronald J. J. Chem. Educ. 1975, 52, 441.
Equilibrium |
Industrial Chemistry |
Chemometrics
Molar solubility calculations and the control equilibrium  Chaston, S. H. H.
The Control-Equilibrium method uses as its starting point a precise procedure for obtaining the equilibrium that accounts for the bulk of the decomposition of starting materials.
Chaston, S. H. H. J. Chem. Educ. 1975, 52, 206.
Solutions / Solvents |
Chemometrics |
Equilibrium
FeSCN2+ - A computer aid to the CHEM Study experiment  McCall, Arthur J., Jr.
A Fortran program assists in making the calculations that accompany investigation of the iron(III)thiocyanate equilibrium system.
McCall, Arthur J., Jr. J. Chem. Educ. 1975, 52, 118.
Equilibrium |
Aqueous Solution Chemistry |
Chemometrics
Component concentrations in solutions of weak acids  Goldish, Dorothy M.
presents a new approach to teaching the subject of weak acid equilibria and its associated calculations.
Goldish, Dorothy M. J. Chem. Educ. 1970, 47, 65.
Acids / Bases |
Aqueous Solution Chemistry |
Equilibrium |
Chemometrics |
pH
Teaching ionic equilibrium: Use of log chart transparencies  Freiser, Henry; Fernando, Quintus
The use of graphical methods brings the problem of significance of various terms in complicated expressions into proper focus. Furthermore, a pictorial representation permits the student to see at a glance how the concentrations of various species in a system at equilibrium change with conditions.
Freiser, Henry; Fernando, Quintus J. Chem. Educ. 1965, 42, 35.
Aqueous Solution Chemistry |
Equilibrium |
Acids / Bases |
pH |
Chemometrics |
Brønsted-Lowry Acids / Bases
An approach to complex equilibrium problems  Butler, James N.
Presents an approach to equilibrium problems that sets up enough equations relating the various concentrations present to define the system completely and then makes approximations that simplify the equations.
Butler, James N. J. Chem. Educ. 1961, 38, 141.
Equilibrium |
Chemometrics |
Acids / Bases |
Aqueous Solution Chemistry
A procedure for solving equilibrium problems  Boyd, Robert Neilson
A procedure for solving equilibrium problems is illustrated through several sample problems.
Boyd, Robert Neilson J. Chem. Educ. 1952, 29, 198.
Equilibrium |
Chemometrics |
Aqueous Solution Chemistry