The formation enthalpies,$\Delta H_{f}^{\ominus}$ for $H_{(g)}$ and $O_{(g)}$ are $220.0$ and $250.0 \ kJ \ mol^{-1}$,respectively,at $298.15 \ K$,and $\Delta H_{f}^{\ominus}$ for $H_2O_{(g)}$ is $-242.0 \ kJ \ mol^{-1}$ at the same temperature. The average bond enthalpy of the $O-H$ bond in water at $298.15 \ K$ is $.......... \ kJ \ mol^{-1}$ (nearest integer).

The total enthalpies of reactants and products are $H_R$ and $H_P$ respectively. For an exothermic reaction,which of the following is true?

What is enthalpy of reaction?

The oxidizing power of chlorine in an aqueous solution can be determined by the parameters given below. What is the total energy change in $kJ \ mol^{-1}$ for the conversion of $\frac{1}{2} Cl_{2(g)}$ to $Cl^-_{(aq)}$?
$\frac{1}{2} Cl_{2(g)}$ $\xrightarrow{\frac{1}{2} \Delta_{diss} H^\Theta} Cl_{(g)}$ $\xrightarrow{\Delta_{eg} H^\Theta} Cl^-_{(g)}$ $\xrightarrow{\Delta_{hyd} H^\Theta} Cl^-_{(aq)}$
(Given: $\Delta_{diss} H_{Cl_2}^\Theta = 240 \ kJ \ mol^{-1}$,$\Delta_{eg} H_{Cl}^\Theta = -349 \ kJ \ mol^{-1}$,$\Delta_{hyd} H_{Cl^-}^\Theta = -381 \ kJ \ mol^{-1}$)

On the basis of the following reactions,which one is correct?
$C_{(gr)} + O_{2_{(g)}} \to CO_{2_{(g)}}, \Delta H = x \ kJ/mol$
$C_{(gr)} + \frac{1}{2} O_{2_{(g)}} \to CO_{(g)}, \Delta H = y \ kJ/mol$
$CO_{(g)} + \frac{1}{2} O_{2_{(g)}} \to CO_{2_{(g)}}, \Delta H = z \ kJ/mol$

For which of the following reactions does the heat of reaction represent the bond energy of $HCl$?