The addition of a dilute solution of bromine in carbon tetrachloride to a compound to test for carbon-carbon multiple bonds, which is one of the widely cited qualitative tests employed in organic chemistry is presented. Major advantages of this approach include the ease and rapidness of the procedure, the stability of the test solution over time,…

Even after repeated instruction, first year college chemistry students are often unable to apply stoichiometry knowledge to equilibrium and acid-base chemistry problems. The dynamic and interactive capabilities of online technology may facilitate stoichiometry instruction that promotes more meaningful learning. This study compares a…

Stoichiometry and related concepts are an important part of student learning in chemistry. In this interpretive-based inquiry, we investigated Thai Grade 10 and 11 students' conceptual understanding and ability to solve numerical problems for stoichiometry-related concepts. Ninety-seven participants completed a purpose-designed survey instrument…

In beginning chemistry classes, students are taught a variety of techniques for balancing chemical equations. The most common method is inspection. This paper addresses using a system of linear mathematical equations to solve for the stoichiometric coefficients. Many linear algebra books carry the standard balancing of chemical equations as an…

Presented are three methods for dealing with chemical problems involving reaction stoichiometry. (RH)

The presentations that will enable students to perform a side-by-side comparison of two conditions and gain better understanding of reactions at equilibrium are illustrated. A novel stoichiometric criterion for identifying equilibria that shift left upon addition of reactant is derived.

The effect of some parameters on sulfurous acid and sulfur oxidation kinetics such as initial concentration of sulfurous acid, oxygen, TiO[2] crystalline concentration, the power of black light, and quantity of TiO[2] is investigated. The experiments can be performed in an undergraduate physical chemistry laboratory with an inexpensive…

An experiment to demonstrate the use of ethylene ketal as a protecting group, one that can be completed in four lab periods, is described. The hydroxy ketone like 4-hydroxy-4, 4-diphenyl-2-butanone formed during the reaction can be identified by its melting point, IR, and (super 1)H NMR.

An experiment is demonstrated to determine the percentage of oxygen in air using a pretreated piece of steel wool, which is an alternative to spectroscopic kinetic analysis. Students are able to determine the order of reaction for oxygen in its reaction with the iron in steel wool, and are able to use the existing technology to collect and analyze…

This article describes the reaction between nitrite and safranine O. This sensitive reaction is based on the disappearance of color of the reddish-orange azo dye, allowing the determination of nitrite at the mg mL-1 level. A factorial optimization of parameters was carried out and the method was applied for the quantification of nitrite in…

Oscillating reactions have been extensively used in chemical demonstrations. They involve several chemical concepts about kinetics, catalysts, and thermodynamics. The spontaneous cyclic color change of a solution is an attraction in any educational-level course. Chemiluminescent reactions are also among the most fascinating demonstrations and have…

The research reported in this case study explores the understanding of stoichiometry and related concepts of Thai science students in grades 10 and 11 after major national curriculum reforms. Students' conceptions and alternative conceptions were investigated using a questionnaire--the "Stoichiometry Concept Questionnaire" (SCQ) (N =…

A novel ratio method is developed and automated for finding the bromine-chlorine-sulfur stoichiometry in the molecular formula of an unknown. This method is also useful in spectrometric analysis or beginning organic chemistry.

Identifies the misunderstandings and problem-solving strategies of secondary students when solving stoichiometry problems. (Author/CCM)

An economically viable and environmental friendly method of generating hydrogen for fuel cells is by the reaction of certain metals with steam, called metal-steam reforming (MSR). This technique does not generate any toxic by-products nor contributes to the undesirable greenhouse effect. From the standpoint of favorable thermodynamics, total…