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 acidbase 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 acidbase 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 chemists 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 AcidBase 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 
BrønstedLowry 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 firstorder 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 firstorder 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 acidbase 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 nonchemical 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 ControlEquilibrium 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 
BrønstedLowry 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

