The standard heat of formation,in $kcal / mol$ of $Ba^{2+}$ is
[Given : standard heat of formation of $SO_4^{2-}$ ion $(aq) = -216 \ kcal / mol$,
Standard heat of crystallisation of $BaSO_{4(s)} = -4.5 \ kcal / mol$,standard heat of formation of $BaSO_{4(s)} = -349 \ kcal / mol$]

Calculate $\Delta_r H$ $(kJ \ mol^{-1})$ of the following reaction:
$C_2H_5OH_{(l)} + \frac{7}{2}O_{2(g)} \rightarrow 2CO_{2(g)} + 3H_2O_{(l)}$

Molecule	$\Delta_f H^0 (kJ \ mol^{-1})$
$C_2H_5OH_{(l)}$	$-280$
$CO_{2(g)}$	$-400$
$H_2O_{(l)}$	$-290$

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

The heat of formation of $H_2O_{(l)}$ is $-68.0 \ kcal$. The heat of formation of $H_2O_{(g)}$ is likely to be........$kcal$.

What is the heat of atomisation of $P_4O_{6(s)}$?
Given that the heat of sublimation of $P_4O_6$ is $x \ kJ/mol$ and the $P-O$ bond energy is $y \ kJ/mol$.

$A$,$B$,$C$ and $D$ are some compounds. The enthalpy of formation of $A_{(g)}$,$B_{(g)}$,$C_{(g)}$ and $D_{(g)}$ is $9.7, -110, 81$ and $-393 \ kJ \ mol^{-1}$ respectively. What is $\Delta_r H$ (in $kJ \ mol^{-1}$) for the given reaction?
$A_{(g)} + 3B_{(g)} \longrightarrow C_{(g)} + 3D_{(g)}$