Stoichiometry Question

Question

C5H12+8 O2 = 5 CO2 + 6 H2O If 128 grams of oxygen react with excess propane, how many grams of water will be generated?

Answer 1

C₅H₁₂ + 8 O₂ = 5 CO₂ + 6 H₂O ... This is the balanced equation

Note that 8 moles of O₂ will produce 6 moles of H₂O. Also note, we work in MOLES not GRAMS.

Moles O₂ present = 128 grams O₂ x 1 moles O₂/32 g = 4 moles O₂ present

Moles of H₂O generated = 4 moles O₂ x 6 moles H₂O/8 moles O₂ = 3 moles H₂O

Grams of H₂O generated = 3 moles H₂O x 18 g/mole = 54 grams of H₂O