The heat liberated when 1.89 g of benzoic acid is burnt in a bomb calorimeter at 25°C increases the temperature of 18.94 kg of water by 0.632°C. If the specific heat of water at `25^(@)C` is 0.998 calg^(-1)deg^(-1),` the value of heat of combustion of benzoic acid is:

Options

A. `88.1 kcal`
B. `771.1 kcal `
C. `981.1 kcal`
D. `871.2 kcal`

Explanation

Heat liberated by `1. 89` g of benzoix acid, ` q = m s Delta T = 18940 xx 0.998 xx 0. 632 = 11946.14` cal
Heat liberated by the combustion of 1 mole benzoic acid i.e., 122 g benzoic acid i.e, 122 g benzoic acid `= ( 119 46 . 14)/(1. 89 ) xx 122 = 771126.5 cal = 771 . 12 kcal mol ^(-1)`