The heat liberated when `1.89 g` of benzoic acid is burnt in a bomb calorimeter at `25^(@)C` increases the temperture of `18.94 kg` of water by `0.632 ^(@)C`. If the specific heat of water at `25^(@)C` is `0.998 cal//g "deg"`, the value of the heat of combustion of benzoic acid is

Options

A. 88.1 kcal
B. 771. 4 kcal
C. 981.1 kcal
D. 871.2 kcal

Answer

B

Explanation

Heat liberated by the combustion of 1 mol bezoic acid i.e., 122 g benzoic acid
`q=msDeltaT`
`=18940xx0.998xx0.632`
`=11946.14cal`
Heat liberated by the combustion of 1 mol benzoic acid ie.., 122 g benzoic acid
`=(11946.14)/(1.89)xx122=771126.5cal`
`=771.12" kcal "mol^-1`