Which sequence correctly converts a mass of reactant to the mass of product using a balanced equation?

• A. Convert the mass of the reactant to moles using n = m/M, multiply by the product’s coefficient, and convert moles of product to mass using its molar mass.
• B. Convert mass to volume, apply the ideal gas law, then convert to mass.
• C. Multiply the mass by the product’s molar mass and divide by the reactant’s molar mass.
• D. Use the density of the reactant to estimate the product mass.

Answer: (A)

Stoichiometry uses the mole ratios from a balanced equation to link masses of reactants and products. Start by converting the given mass of the reactant to moles using its molar mass. Then apply the mole ratio from the balanced equation to get moles of the product (multiply by the product’s coefficient and divide by the reactant’s coefficient). Finally, convert those product moles to mass using the product’s molar mass. This sequence directly uses the way a balanced equation enforces how much of each substance reacts and forms. Other methods, like switching to volume with the ideal gas law or using a direct mass ratio of molar masses, don’t generally reflect the actual stoichiometric relationships unless the specific conditions and coefficients are accounted for.