Demonstrations to Increase Understanding of Topics in General Chemistry Courses: Equilibrium, Enthalpy, and Colligative Properties
Key Words: equilibrium, Le Chatelier’s principle, enthalpy, colligative properties, vapor pressure lowering, demonstrations, general chemistry
Without experiments or demonstrations, chemical concepts can be difficult to visualize. Textbooks and lectures simply introduce students to chemistry, while demonstrations allow students to relate their knowledge to real world examples and intrigue students’ interest. The purpose of this project was to perform and film demonstrations for general chemistry courses to increase students’ understanding of three chemical topics including equilibrium, enthalpy, and vapor pressure lowering.
First the cobalt chloride reaction was used to illustrate equilibrium. Students observed the effects of temperature and on a system at equilibrium through color changes. Next, the endothermic reaction between acetic acid and sodium bicarbonate was performed to demonstrate enthalpy. The change in heat was observed using a thermometer. Finally, a demonstration for vapor pressure lowering was constructed. Students observed decreased vapor pressure between flasks of salt water and distilled water by qualitatively comparing the amount of condensation in each flask.
As a result, three videos were made to demonstrate the three topics as stated above. These videos enhanced students’ learning by simultaneously providing visualization and explanation of topics students find challenging in general chemistry courses.