The difference between heats of reaction at constant pressure and constant volume for the reaction

2C₆H₆ (I) + 150₂(g) 12CO₂ (g) + 6H₂O (I)

at 25?C in kJ mol^-1 is

1)

-7.43

2)

+3.72

3)

-3.72

4)

+7.43

Dear Student,

Heat of reaction at constant pressure is ΔH and at constant volume is ΔU.

ΔH-ΔU=Δn_gRT

Δn_g=12-15=-3

Δn_gRT=(-3)*(8.314*10^-3KJ/mol/K)*(298 K)=-7.43

one more thing,someone may think of dividing the reaction by 2..but that will be wrong.

On multiplying by a factor,ΔH and ΔU also get multiplied by the factor..

All the best Pratik !!!




Regards,

Askiitians Experts

Sahil Arora