chemistry question

Question

If 128 grams of CH₄ and 160 grams of O₂ react, how many miles of CO₂ will form. What would be the limiting reactant/excess reactant and the theoretical yield?

Answer 1

An easy way to find the limiting reactant is to divide the mols of each reactant by its coefficient in the balanced equation, and whichever is less, that is the limiting reactant.

CH₄ + 2O₂ ==> CO₂ + 2H₂O ... balanced equation

CH₄: 128 g x 1 mol / 16 g = 8 mols CH₄ (÷ 1 -> 8)

O₂: 160 g x 1 mol / 32 g = 5 mols O₂ (÷ 2 -> 2.5)

Clearly O₂ is limiting

Excess reactant is CH₄

Theoretical yield is determined by the limiting reactant.

Theoretical yield = 5 mols O₂ x 1 mol CO₂ / 2 mols O₂ x 44 g CO₂ / mol CO₂ = 110 g CO₂