Q53. Combustion of 1 mole of benzene is expressed at $\mathrm { C } _ { 6 } \mathrm { H } _ { 6 } ( \mathrm { l } ) + \frac { 15 } { 2 } \mathrm { O } _ { 2 } ( \mathrm {~g} ) \rightarrow 6 \mathrm { CO } _ { 2 } ( \mathrm {~g} ) + 3 \mathrm { H } _ { 2 } \mathrm { O } ( \mathrm { l } )$. The standard enthalpy of combustion of 2 mol of benzene is $- ^ { \prime } x ^ { \prime } \mathrm { kJ } . x =$ $\_\_\_\_$ Given: 1. standard Enthalpy of formation of 1 mol of $\mathrm { C } _ { 6 } \mathrm { H } _ { 6 } ( \mathrm { l } )$, for the reaction 6 C (graphite) $+ 3 \mathrm { H } _ { 2 } ( \mathrm {~g} ) \rightarrow \mathrm { C } _ { 6 } \mathrm { H } _ { 6 } ( \mathrm { l } )$ is $48.5 \mathrm {~kJ} \mathrm {~mol} ^ { - 1 }$. 2. Standard Enthalpy of formation of 1 mol of $\mathrm { CO } _ { 2 } ( \mathrm {~g} )$, for the reaction C (graphite) $+ \mathrm { O } _ { 2 } ( \mathrm {~g} ) \rightarrow \mathrm { CO } _ { 2 } ( \mathrm {~g} )$ is $- 393.5 \mathrm {~kJ} \mathrm {~mol} ^ { - 1 } .3$. Standard and Enthalpy of formation of 1 mol of $\mathrm { H } _ { 2 } \mathrm { O } ( \mathrm { l } )$, for the reaction $\mathrm { H } _ { 2 } ( \mathrm {~g} ) + \frac { 1 } { 2 } \mathrm { O } _ { 2 } ( \mathrm {~g} ) \rightarrow \mathrm { H } _ { 2 } \mathrm { O } ( \mathrm { l } )$ is $- 286 \mathrm {~kJ} \mathrm {~mol} ^ { - 1 }$.