The enthalpy changes at $298 \ K$ in successive breaking of $O-H$ bonds of $H_2O$ are:
$H_2O_{(g)} \to H_{(g)} + OH_{(g)}, \Delta H = 498 \ kJ \ mol^{-1}$
$OH_{(g)} \to H_{(g)} + O_{(g)}, \Delta H = 428 \ kJ \ mol^{-1}$
The bond enthalpy of the $O-H$ bond is ..... $kJ \ mol^{-1}$.

Determine the enthalpy of formation for $H_2O_{2(l)}$,using the listed enthalpies of reaction:
$N_2H_{4(l)} + 2H_2O_{2(l)} \to N_{2(g)} + 4H_2O_{(l)}$; $\Delta_r H_1^o = -818 \ kJ/mol$
$N_2H_{4(l)} + O_{2(g)} \to N_{2(g)} + 2H_2O_{(l)}$; $\Delta_r H_2^o = -622 \ kJ/mol$
$H_{2(g)} + \frac{1}{2}O_{2(g)} \to H_2O_{(l)}$; $\Delta_r H_3^o = -285 \ kJ/mol$

Given the following thermochemical equations:
$1) \ C_{(s)} + O_{2(g)} \rightarrow CO_{2(g)}, \Delta H = -787 \ kJ$
$2) \ H_{2(g)} + \frac{1}{2} O_{2(g)} \rightarrow H_2O_{(l)}, \Delta H = -286 \ kJ$
$3) \ C_2H_{2(g)} + \frac{5}{2} O_{2(g)} \rightarrow 2CO_{2(g)} + H_2O_{(l)}, \Delta H = -1310 \ kJ$
Calculate the enthalpy of formation of acetylene $(C_2H_{2(g)})$ in $kJ \ mol^{-1}$.

From the following bond energies:

$H-H$ bond energy	$431.37 \text{ kJ mol}^{-1}$
$C=C$ bond energy	$606.10 \text{ kJ mol}^{-1}$
$C-C$ bond energy	$336.49 \text{ kJ mol}^{-1}$
$C-H$ bond energy	$410.50 \text{ kJ mol}^{-1}$

Enthalpy for the reaction $CH_2=CH_2 + H-H \to CH_3-CH_3$ will be .............. $\text{kJ mol}^{-1}$

Carbon and carbon monoxide burn in oxygen to form carbon dioxide according to the following reactions:
$C(s) + O_2(g) \to CO_2(g)$; $\Delta H = -394 \ kJ \ mol^{-1}$
$2CO(g) + O_2(g) \to 2CO_2(g)$; $\Delta H = -569 \ kJ \ mol^{-1}$
The heat of formation of $1 \ mol$ of carbon monoxide is thus ..... $kJ \ mol^{-1}$.

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