Final answer:
To calculate the theoretical yield of a thermal decomposition reaction, write the balanced reaction equation, convert the given mass of reactant to moles, use the stoichiometric ratios to find moles of product, and convert those moles to mass. The percent yield is determined by comparing the actual yield to the theoretical yield.
Step-by-step explanation:
To find the theoretical yield of a thermal decomposition reaction, we first need to write out the balanced chemical equation for the reaction. For example, in the decomposition of potassium chlorate (KClO3), the balanced equation is 2KClO3 (s) → 2KCl (s) + 3O2 (g). Using the molar mass of KClO3 and the stoichiometry of the reaction, we can calculate the maximum amount of product that can be formed from a given amount of reactant.
For a given mass of KClO3, first convert this mass to moles by dividing by the molar mass of KClO3. Then, use the mole ratio from the balanced equation to find the moles of oxygen gas (O2) produced. Finally, convert the moles of O2 to grams using the molar mass of O2. This is the theoretical yield of oxygen gas. The percent yield is then found by taking the actual yield (the mass of O2 collected), dividing by the theoretical yield, and multiplying by 100.