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 =…

Under conditions of constant temperature T and pressure P, chemical equilibrium occurs in a closed system (fixed mass) when the Gibbs free energy G of the reaction mixture is minimized. However, when chemical reactions occur under other conditions, other thermodynamic functions are minimized or maximized. For processes at constant T and volume V,…

The aim of this study is to investigate Emiratii high school students' understandings of stoichiometry, their use of metacognitive strategies, and the influence of students' use of metacognitive strategies on their understandings of stoichiometry. Two instruments were used in this study, the first to measure students' understandings of…

A simple algorithm for a complete enumeration of the possible ways a redox reaction (RR) might be uniquely decomposed into half-reactions (HRs) using the response reactions (RERs) formalism is presented. A complete enumeration of the possible ways a RR may be decomposed into HRs is equivalent to a complete enumeration of stoichiometrically…

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 study focuses on percarbonate-based stain removers since the percarbonate can be heated to produce additional sodium carbonate. An experiment that provides general chemistry students an opportunity to apply their knowledge of basic stoichiometry to solve a relevant, real-world problem is described.

Do students who focus on some content areas in high school chemistry have an advantage over others in college chemistry? Published research on high school preparation for college science dates back as far as the 1920s, but results have been mixed. This manuscript seeks to answer this question through the use of a broad-based survey of 3521…

This study researched the use of writing-to-learn strategies within a high-school (Year 11) chemistry classroom. The writing task itself asked the students to write a business letter to a younger audience of middle-school (Year 7) students. A mixed-method design was used for the study, incorporating pre/post- testing with semi-structured…

Describes a demonstration of the decomposition of hydrogen peroxide to provide an interesting, quantitative illustration of the stoichiometric relationship between the decomposition of hydrogen peroxide and the formation of oxygen gas. This 10-minute demonstration uses ordinary hydrogen peroxide and yeast that can be purchased in a supermarket.…

A sensor experiment which can be applied to advanced undergraduate laboratory course in physical or analytical chemistry is described along with certain concepts like the demonstration of chemical sensing, preparation of thin films on a substrate, microtitration, optical determination of complex ion stoichiometry and isosbestic point. It is seen…

Discusses an instructional strategy in which stoichiometric reactions are presented in terms of a recipe. Solutions for two different stoichiometric problems are included. (JN)

Pictorial analogies that demonstrate concepts of amounts allow instructors to teach that in stoichiometric problems, the number--or moles--of molecules of a chemical is what matters, even though it must be measured in masses or volumes. Analogies to stoichiometric relationships include the ratio of four wheels to one body in making wagons and…

Describes a low-cost activity designed to help students visualize both the kinetic and the stoichiometric nature of chemical reactions at the particle level, by creating a flip book. Suggests ideas for evaluation of student work, and extension activities. (WRM)