$C_{(diamond)} + O_2 \to CO_2; \Delta H = -395.3 \ kJ/mole$
$C_{(graphite)} + O_2 \to CO_2; \Delta H = -393.4 \ kJ/mole$
$C_{(graphite)} \to C_{(diamond)}; \Delta H = ?$

The heat of formation of $SiO_2$ and $MgO$ is respectively $-48.4 \ kJ$ and $-34.7 \ kJ$. The heat of the reaction $2Mg + SiO_2 \to 2MgO + Si$ is $...... \ kJ$.

"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

Which of the following reactions defines the standard enthalpy of combustion,$\Delta H_c^ \circ$?

State and prove Hess's law of constant heat summation.

Calculate the standard enthalpy change of the reaction: $C_2H_{2(g)} + \frac{5}{2}O_{2(g)} \rightarrow 2CO_{2(g)} + H_2O_{(\ell)}$ given the following standard enthalpies of formation:
$\Delta_fH^{\circ}(CO_2) = -393 \ kJ \ mol^{-1}$
$\Delta_fH^{\circ}(H_2O) = -286 \ kJ \ mol^{-1}$
$\Delta_fH^{\circ}(C_2H_2) = 227 \ kJ \ mol^{-1}$