In the following reaction, what quantity in moles of CH₃OH are required to give off 1501 kJ of heat? 2 CH₃OH (l) + 3 O₂ (g) → 2 CO₂ (g) + 4 H₂O(g) ∆H° = -1280. kJ

Answer 1

2 CH₃OH (l) + 3 O₂ (g) → 2 CO₂ (g) + 4 H₂O(g) .. ∆Hº = -1280 kJ

The balanced equation tells us that when TWO moles CH₃OH are combusted, the heat released is 1280 kJ.

Now simply use dimensional analysis (unit factor) to find number of moles CH3OH to give 1501 kJ:

1501 kJ x 2 mols CH₃OH / 1280 kJ = 2.35 mols CH₃OH