How do you calculate a theoretical yield in a chemical reaction from a balanced equation?

How do you calculate a theoretical yield in a chemical reaction from a balanced equation?

• A. Use the mass of product observed experimentally
• B. Determine moles of limiting reactant from its mass, use stoichiometry to find moles of product, convert to mass
• C. Use the mass of the excess reactant
• D. Use the density of the product

Answer: (B)

The main idea is to use stoichiometry with the limiting reactant. First, convert the masses of all reactants to moles, then compare those amounts using the balanced equation to see which reactant runs out first—the limiting reactant. The product mass you can form is determined by this reactant: multiply the moles of the limiting reactant by the product-to-limiting-reactant ratio from the balanced equation to get moles of product, then convert that to grams with the product’s molar mass. This gives the theoretical yield—the maximum mass of product possible if the reaction goes to completion with no losses. The other options describe actual yield (observed mass) or rely on information that doesn’t determine how much product can form (the mass of an excess reactant or the product’s density).

The main idea is to use stoichiometry with the limiting reactant. First, convert the masses of all reactants to moles, then compare those amounts using the balanced equation to see which reactant runs out first—the limiting reactant. The product mass you can form is determined by this reactant: multiply the moles of the limiting reactant by the product-to-limiting-reactant ratio from the balanced equation to get moles of product, then convert that to grams with the product’s molar mass. This gives the theoretical yield—the maximum mass of product possible if the reaction goes to completion with no losses. The other options describe actual yield (observed mass) or rely on information that doesn’t determine how much product can form (the mass of an excess reactant or the product’s density).