Stoichiometry Calculator

Perform stoichiometric calculations to determine limiting reactants and theoretical yields.

Calculate Yields

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Worked Examples: Limiting Reactant & Yield

Example 1: Water from H2 and O2

Balanced: 2H2 + O2 → 2H2O. Given 4.00 g H2 and 32.0 g O2, find the limiting reactant and yield of H2O.

  1. n(H2) = 4.00 g / 2.016 g·mol−1 = 1.984 mol.
  2. n(O2) = 32.0 g / 32.00 g·mol−1 = 1.000 mol.
  3. Stoichiometric ratios: need 2 mol H2 per 1 mol O2. Ratios: H2: 1.984/2 = 0.992; O2: 1.000/1 = 1.000 → limiting is H2.
  4. Product moles: n(H2O) = 2 × 0.992 = 1.984 mol → mass = 1.984 × 18.015 = 35.7 g.

Example 2: CO2 from CaCO3

Balanced: CaCO3(s) → CaO(s) + CO2(g). If you decompose 25.0 g CaCO3, what is the theoretical yield of CO2?

  1. M(CaCO3) ≈ 100.09 g·mol−1; n = 25.0 / 100.09 = 0.2498 mol.
  2. Stoichiometry 1:1 → n(CO2) = 0.2498 mol.
  3. Mass CO2 = 0.2498 × 44.01 = 11.0 g.