For the reaction,$H_{2(g)} + I_{2(g)} \to 2HI_{(g)}$,$\Delta H = -12.40 \ kcal$. According to this,the heat of formation of $HI$ will be......$kcal$.

Which of the following reactions represents the standard heat of formation of the product?

If the enthalpy change during the combustion of benzene is $-3264.6 \ kJ/mol$,then the heat produced by the combustion of $39 \ g$ of benzene is ...... $kJ$.

Calculate the enthalpy of formation of ethylene $(C_2H_4)$ from the following data:
$(I)$ $C_{\text{(graphite)}} + O_{2(g)} \longrightarrow CO_{2(g)}$; $\Delta H = -393.5 \ kJ$
$(II)$ $H_{2(g)} + \frac{1}{2} O_{2(g)} \longrightarrow H_2O_{(l)}$; $\Delta U = -256.2 \ kJ$
$(III)$ $C_2H_{4(g)} + 3 O_{2(g)} \longrightarrow 2 CO_{2(g)} + 2 H_2O_{(l)}$; $\Delta H = -1410.8 \ kJ$ (in $kJ$)

The bond enthalpies of heavy hydrogen $(D-D)$,oxygen $(O=O)$,and heavy water $(D-O)$ are $+400$,$+498$,and $+490 \ kJ \ mol^{-1}$,respectively. The $\Delta_{r} H^{\circ}$ of the reaction to produce $D_2O$ is:

If $8.84 \ kJ$ heat is liberated for the formation of $3 \ g$ of ethane,calculate its $\Delta_{f} H^{\circ}$.