When 1.0 g of oxalic acid `(H_(2)C_(2)O_(4))` is burnt in a bomb calorimeter whose capacity is 8.75 KJ/K, the enthalpy of combustion of oxalic acid at`27^(@)C` is :

Options

A. `-245.7 kJ//mol`
B. `-2.43.45 kJ//mol`
C. `-246.95 kJ//mol`
D. `-241.95 kJ//mol`

Answer

D

Explanation

`H_(2)C_(2)O_(4)(l)+(1)/(2)O_(2)(g) rarr H_(2)O(l) + 2CO_(2)(g)`,
`Delta n_(g) = 3//2, Delta U_(c) = -(0.312 xx 8.75)/(1) xx 90`
`= -245.7 kJ//mol`,
`Delta H = Delta U + Delta n_(g)RT`
`= -245.7+(3)/(2) xx (8.314 xx 300)/(1000) = -241.95 KJ//mol`