Molar ratios

Science

Definition

Molar ratios are the proportional relationships between the amounts (in moles) of reactants and products in a balanced chemical equation. They serve as conversion factors for stoichiometric calculations, allowing you to predict how much product forms or how much reactant is needed.

Examples

  • In 2H₂ + O₂ → 2H₂O, the molar ratio of H₂ to O₂ is 2:1
  • Using the ratio to calculate that 4 moles of H₂ requires 2 moles of O₂
  • Determining grams of CO₂ produced from a known mass of glucose burned
Key Fact

Molar ratios come directly from the coefficients in a balanced equation.

Related Terms

Stoichiometry Balancing equations Limiting reagents Percent yield

Study This Concept

Practice molar ratios with free review games in these units:

Chemistry Unit 5: Stoichiometry