Matching Five White Solids to Common Chemicals: A Dissolution Calorimetry and Acid–Base Titration Experiment

Abstract

An experiment to match five white solids with ascorbic acid, citric acid, potassium hydroxide, sodium chloride, and urea is reported here. This 4 h experiment is an integrated practice of two experimental techniques, calorimetry and titration. Students conduct an extensive literature search on the properties of the five compounds and plan the experiment before the laboratory hours. Calorimetric results are used to identify potassium hydroxide, sodium chloride, and urea out of the five compounds. Acid–base titration is used to differentiate between the two weak acids and confirm the identity of the only base in this experiment. Additional calculations based on titration results can reveal waters of crystallization in citric acid and potassium hydroxide. The experiment helps students to understand concepts of dissolution, stoichiometry, acid–base chemistry, and thermochemistry in the context of common chemicals found in everyday life.