Question

Benzene burns in oxygen according to the following reaction

C6H6(l) + 15/2 O2(g)  2H2O(l) + 6CO2(g)

If standard heats of formation (fH

) of C6H6(l), H2O(l) and CO2(g) are given to be

49.0, -286 and -394kJ mol-1

respectively, calculate the amount of heat liberated by

burning 1kg of benzen​

Answer 1

Answer:

C

6

H

6

(l)+

2

15

O

2

(g)⟶3H

2

O(l)+6CO

2

(g)

enthalpies of formation

C

6

H

6

→11.7,H

2

O→−68.1,CO

2

→−94

Enthalpy of reaction is 3(−681)+3(−94)−1(11.7)

=−780Kcal

This enthalpy is for 1 mol (78 g) of benzene.

for 780 g of benzene

7800kcal is the amount of heat required.