The enthalpy of formation for `C_(2)H_(4)(g)`, `CO_(2)(g)` and `H_(2)O(l)` at `25^(@)C` and `1` atm. Pressure be `52`, `-394` and `-286 kJ mol^(-1)` respectively. The enthalpy of combustion of `C_(2)H_(4)(g)` will be

Options

A. `+1412 kJ mol^-1`
B. `-1412 kJ mo1^-1 `
C. `+1 41.2 kJ mo1^-1`
D. `-141.2 kJ mol^-1`

Answer

B

Explanation

`C_2 H_4 + 3O_2 rarr 2 CO_2 + 2H_2O`.
`Delta H_("reaction " )= [2xx Delta_f H^(@) (CO_2) +2 Delta_f H^@(O_2)]`
`=[ 2 xx (-394) +2 (-286)]-[ 52+0]`
`= -1412 kJ.`