Given that the heat of reaction for $A + \frac{1}{2} O_2 \to AO$ is $-50 \ kcal$ and for $AO + \frac{1}{2} O_2 \to AO_2$ is $100 \ kcal$. Find the heat of reaction for $A + O_2 \to AO_2$ in $kcal$.

At $1 \ bar$ and $298 \ K$,the standard molar enthalpy of formation of which substance is zero?

For the reaction $C(s) + O_2(g) \rightarrow CO_2(g)$,the enthalpy change $(\Delta H)$ is:

Calculate $\Delta H$ in $kJ$ for the following reaction:
$C_{(s)} + O_{2(g)} \longrightarrow CO_{2(g)}$
Given that:
$H_2O_{(g)} + C_{(s)} \longrightarrow CO_{(g)} + H_{2(g)} ; \Delta H = +131 \ kJ$
$CO_{(g)} + \frac{1}{2} O_{2(g)} \longrightarrow CO_{2(g)} ; \Delta H = -282 \ kJ$
$H_{2(g)} + \frac{1}{2} O_{2(g)} \longrightarrow H_2O_{(g)} ; \Delta H = -242 \ kJ$

If the bond formation energy of the $H-H$ bond is $-433 \ kJ \ mol^{-1}$,find the bond dissociation energy for $0.5 \ mol$ of $H_{2(g)}$. (in $kJ$)

The enthalpies of dissolution of $BaCl_2(s)$ and $BaCl_2 \cdot 2H_2O(s)$ are $-20.6 \ kJ \ mol^{-1}$ and $8.8 \ kJ \ mol^{-1}$ respectively. Calculate the enthalpy of hydration for the given reaction: $BaCl_2(s) + 2H_2O(l) \to BaCl_2 \cdot 2H_2O(s)$