The course description for the College Board AP®
Chemistry lists the following topics for stoichiometry: net ionic equations, balancing equations and mass and volume relationships relating to the mole concept, empirical formulas and limiting reactants. Use this set of three acid–base heat of neutralization demonstrations to both engage students in a hands-on review and to test their understanding of this sometimes difficult yet fundamental topic.
- Acid–Base Neutralization of Acetic—Acid Start the review with mono-protic acetic acid. Use the method of continuous variations to mix the reactants. Students then graph the change in temperature versus the volume of acid to determine the mole ration of two reactants.
- Di-Protic Acid Neutralization—Once students are comfortable with the continuous variations method, switch to equal molar volumes of sodium hydroxide and the di-protic weak acid, oxalic acid.
- Neutralization of Poly-protic Citric Acid—The menioned stoichiometry topics all come together in this final demonstration.
Balancing equations, mole ratio, net ionic equations, empirical formulas, limiting reactions. Time Required:
One class period
Materials Included in Kit:
Acetic acid solution, 0.8 M, 300 mL
Citric acid solution, 0.8 M, 300 mL
Oxalic acid solution, 0.8 M, 300 mL
Phenolphthalein solution, dropper bottle, 1%, 30 mL
Potassium hydrogen phthalate, 4 g
Sodium hydroxide solution, 0.8 M, 500 mL, 3
Cup, polystyrene, 8 oz, 12