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.

Consider the reaction $2H_2S(g) + 3O_2(g) \rightarrow 2H_2O(l) + 2SO_2(g)$. The magnitude of enthalpy change for the reaction in $\text{kJ mol}^{-1}$ is . . . . . . . (Nearest integer). Given: $\Delta_f H^\circ(H_2S) = -20.1 \text{ kJ mol}^{-1}$, $\Delta_f H^\circ(H_2O) = -286.0 \text{ kJ mol}^{-1}$, $\Delta_f H^\circ(SO_2) = -297.0 \text{ kJ mol}^{-1}$

Given $\Delta H_f^{\circ}$ for $CO_{2(g)}$, $CO_{(g)}$ and $H_2 O_{(g)}$ are $-393.5$, $-110.5$ and $-241.8 \ kJ \ mol^{-1}$, respectively. The $\Delta H_r^{\circ}$ [in $kJ \ mol^{-1}$] for the reaction $CO_{2(g)} + H_{2(g)} \longrightarrow CO_{(g)} + H_2 O_{(g)}$ is

The enthalpy changes for the following reactions are given:
$Cl_{2(g)} = 2Cl_{(g)}, 242.3 \, kJ \, mol^{-1}$; $I_{2(g)} = 2I_{(g)}, 151.0 \, kJ \, mol^{-1}$
$ICl_{(g)} = I_{(g)} + Cl_{(g)}, 211.3 \, kJ \, mol^{-1}$; $I_{2(s)} = I_{2(g)}, 62.76 \, kJ \, mol^{-1}$
Given that the standard states of iodine and chlorine are $I_{2(s)}$ and $Cl_{2(g)}$,the standard enthalpy of formation for $ICl_{(g)}$ is $...... \, kJ \, mol^{-1}$.

If heat of neutralization is $-13.7 \, KCal$ at $25 \, ^oC$ and $\Delta H_f^o (H_2O) = -68 \, KCal$,then the standard enthalpy of formation of $OH^{-}$ will be.....$KCal$. (in $.3$)

The standard enthalpy of formation of $CO_{2(g)}$,$CaO_{(s)}$ and $CaCO_{3(s)}$ are $-393, -634, -1210 \ kJ \ mol^{-1}$ respectively. If all the substances are in standard state,the standard enthalpy of decomposition of calcium carbonate to $CaO_{(s)}$ and $CO_{2(g)}$ (in $kJ \ mol^{-1}$) is