The effect of wording of questions on student responses to equilibrium problems in chemistry

Abstract

Chemical equilibrium is considered to be one of the most difficult topics in chemistry as it is abstract and dependent on a large amount of pre-knowledge. Various studies have been done about the misconceptions high school learners, undergraduate students and even chemistry teachers and lecturers have about the topic. Another problem that has been identified with chemistry in general and chemical equilibrium in particular is the use of language as everyday words often have a different meaning when used in a scientific context. The focus of this dissertation is to investigate the effect of wording of questions on student responses when solving problems concerning chemical equilibrium. A two-part questionnaire was designed to test the student responses on questions involving the application of Le Chatelier’s principle with changes in temperature and pressure for gaseous systems, and equilibrium constant calculations. In the first part of the questionnaire the heat involved in the reaction was described using the correct scientific terms, as well as descriptions with everyday words. The change in pressure was described as either a change in pressure or a change in volume. In the second part of the questionnaire the format in which the data for equilibrium constant calculations was given was varied. Interviews were conducted with selected students to determine the reasons for their answers. The questionnaire was administered to 201 students in the first year General Chemistry course at the Potchefstroom Campus of the North-West University. It was expected that the wording used to describe the equilibrium system or the change would have an effect on the student responses. The analysis of the results as well as the interviews confirmed this expectation. The students fared better when the terms exothermic and endothermic were used, rather than descriptions of heat being released or absorbed. The students also fared better when changes in pressure were given instead of changes in volume. In addition it was found that the students relied on rote-learning rather than a thorough understanding of the concepts involved to solve problems relating to the application of Le Chatelier’s principle. When calculating the equilibrium constant the students had more difficulty when the volume needed to calculate the equilibrium concentrations were given in scientific notation or a different unit. The students also struggled when the amounts of the substances involved was given in different units and some of the students were not able to correctly identify whether the given amount of substance was used during the course of the reaction or remaining when equilibrium was reached.