Acetylene, C2H2, combusts in the presence of oxygen to form carbon dioxide and steam as shown in the following reaction.

Question

2 C2H2 + 5 O2 → 4 CO2 + 2 H2O

ΔH° = -2511.6 kJ/molrxn

Calculate the amount of energy released when 39.0 g C2H2 reacts with excess oxygen.

Answer 1

molar mass C2H2 = 26 g / mol

39.0 g C2H2 x 1 mol / 26 g = 1.50 mols C2H2

Energy released = -2511.6 kJ / mol x 1.50 mol = -3767 kJ