What is the heat of reaction for C2H4 + 3O2 -> 2CO2 + 2H2O, if heat of formation of C2H4, O2, CO2, and H2O are 10 J, 5 J, 6 J and 2 J respectively?

Question

What is the heat of reaction for C2H4 + 3O2 -> 2CO2 + 2H2O, if heat of formation of C2H4, O2, CO2, and H2O are 10 J, 5 J, 6 J and 2 J respectively?

(a) -4 J

(b) -2 J

(c) 0

(d) 4 J

Answer 1

Right answer is (a) -4 J

Explanation: Heat of reaction = 2*2 + 2*6 – 10 – 2*5 = -4 J.