Most stoichiometry calculations in the classroom use exact (stoichiometric) mole ratios of reactants and products; however, many commercial processes for preparing compounds use an excess amount of one reactant (and a limiting amount of another). The Stoichiometry Balloon Races: Limiting and Excess Reactants—ChemTopic™ Lab Activity illustrates limiting and excess reactants by comparing the amounts of carbon dioxide generated when varying amounts of sodium bicarbonate react with acetic acid. Available as part of the Molar Relationships & Stoichiometry—ChemTopic™ Labs digital collection. Click the Price link for digital collection pricing.