Given $C + O_2 \rightarrow CO_2$ : $\Delta H = -x \ kJ$ and $2CO + O_2 \rightarrow 2CO_2$ : $\Delta H^\circ = -y \ kJ$,find the enthalpy of formation of carbon monoxide.

Calculate the change in enthalpy when $39 \ g$ of acetylene is completely burnt with oxygen,given that the enthalpy of combustion of acetylene is $1300 \ kJ \ mol^{-1}$. (in $kJ$)

The enthalpy of formation of $NH_3$ is $-46 \ kJ \ mol^{-1}$. The enthalpy change for the reaction $2 NH_{3(g)} \longrightarrow N_{2(g)} + 3 H_{2(g)}$ is

Calculate the heat change for the reaction $4NH_3(g) + 3O_2(g) \rightarrow 2N_2(g) + 6H_2O(l)$ in $kJ$. The enthalpies of formation of $NH_3(g)$ and $H_2O(l)$ at $298 \ K$ are $-46.0 \ kJ \ mol^{-1}$ and $-286.0 \ kJ \ mol^{-1}$ respectively.

At $300 \, K$,the standard enthalpies of formation of $C_6H_5COOH_{(s)}$,$CO_{2_{(g)}}$,and $H_2O_{(l)}$ are $-408$,$-393$,and $-286 \, kJ \, mol^{-1}$ respectively. What is the heat of combustion of benzoic acid at constant volume in $kJ$ (in $.75$)? $(R = 8.31 \, J \, mol^{-1} \, K^{-1})$

The enthalpies of combustion of diamond and graphite are $-395.4 \, kJ$ and $-393.5 \, kJ$ respectively. The enthalpy of transformation of diamond to graphite is ..... $kJ$.