The bond energies of $C-C$,$C=C$,$H-H$,and $C-H$ bonds are $350$,$600$,$400$,and $410 \ kJ \cdot mol^{-1}$ respectively. The heat of hydrogenation of ethylene $(C_2H_4)$ is ... $kJ \cdot mol^{-1}$.

$2.1 \ g$ of $Fe$ combines with $S$ evolving $3.77 \ kJ$. The heat of formation of $FeS$ in $kJ/mol$ is

Which of the following values of heat of formation indicates that the product is least stable in $kcal$?

$Fe_2O_{3(s)} + \frac{3}{2} C_{(s)} \to \frac{3}{2} CO_{2(g)} + 2Fe_{(s)}$
$\Delta H^o = +234.1 \ kJ$
$C_{(s)} + O_{2(g)} \to CO_{2(g)}$
$\Delta H^o = -393.5 \ kJ$
Use these equations and $\Delta H^o$ values to calculate $\Delta H^o$ for this reaction:
$4Fe_{(s)} + 3O_{2(g)} \to 2Fe_2O_{3(s)}$
..... $kJ$

"The quantity of heat which must be supplied to decompose a compound into its elements is equal to the heat evolved during the formation of that compound from the elements." This statement is known as

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