If $38.55 \ kJ$ of heat is absorbed when $6.0 \ g$ of $O_2$ reacts with $ClF$ according to the reaction $2ClF_{(g)} + O_{2(g)} \longrightarrow Cl_2O_{(g)} + OF_{2(g)}$. What is the standard enthalpy of reaction (in $kJ$)?

In the reaction $S + \frac{3}{2} O_{2} \rightarrow SO_{3} + 2x \ kJ$ and $SO_{2} + \frac{1}{2} O_{2} \rightarrow SO_{3} + y \ kJ$,the heat of formation of $SO_{2}$ is

The enthalpies of formation of $CO_{2(g)}$,$H_2O_{(g)}$,and $C_2H_{4(g)}$ are $-393.7$,$-241.8$,and $52.3 \ kJ \ mol^{-1}$ respectively. What will be the enthalpy of combustion of ethylene at $298 \ K$ and $1 \ atm$ pressure in $kJ \ mol^{-1}$?

The standard enthalpy of formation,$\Delta H^o_f$ $(298 \ K)$,of methanol is represented by which of the following chemical equations?

Calculate the standard enthalpy change of the following reaction:
$C_2H_{4(g)} + 3O_{2(g)} \longrightarrow 2CO_{2(g)} + 2H_2O_{(\ell)}$
Given:
$\Delta_{f}H^{\circ}(C_2H_4) = 52 \ kJ \ mol^{-1}$
$\Delta_{f}H^{\circ}(CO_2) = -393.5 \ kJ \ mol^{-1}$
$\Delta_{f}H^{\circ}(H_2O) = -285.8 \ kJ \ mol^{-1}$
(Note: Standard values adjusted for accuracy)

When $4 \ g$ of iron is burnt to ferric oxide at constant pressure,$29.28 \ kJ$ of heat is evolved. What is the enthalpy of formation of ferric oxide in $kJ \ mol^{-1}$? (At. Wt. of $Fe = 56$)