the heat of combustion of benzene in a bomb calorimeter was found to be 3263 9 kj/mol at 25 C - Chemistry - Thermodynamics

Question

the heat of combustion of benzene in a bomb calorimeter was
found to be 3263 9 kj/mol at 25 C calculate the heat of combustion
of benzene at constant pressure?

Priya G N · Accepted Answer

Let us first write reaction of combustion in benzene C6H6 + 7Â½O2 (g) -----> 6CO2 (g) + 3H2O (l) In the above reaction O2 and CO2 are the only gases

g = no of moles of products â€“ no of moles of reactants = 6 - 7Â½ = - 1 Â½ = -3/2 Given values

U = 3263 9 kJ/mol; T = 298 K; As we know,

H =

U +

ng RT R = 8 314

As this is an exothermic reaction

H is negative

H = (- 3263 9 kJ/mol) + (-3/2)

(298 K) = (- 3263 9 kJ/mol) + (-3/2) (2 477) = (- 3263 9 kJ/mol) â€“ 3 716 kJ/mol

H = - 3267 6 kJ/mol

the heat of combustion of benzene in a bomb calorimeter was found to be 3263.9 kj/mol at 25 C.calculate the heat of combustion of benzene at constant pressure?