Consider the reaction $4NO_2(g) + O_2(g) \rightarrow 2N_2O_5(g)$, $\Delta_rH = -111 \ kJ$. If $N_2O_5(s)$ is formed instead of $N_2O_5(g)$, what will be the value of $\Delta_rH$ in $kJ$? (Given: $\Delta H_{sub} = 54 \ kJ \ mol^{-1}$ for $N_2O_5$)

Which is the best definition of “heat of neutralization”?

The reaction of methanol $(\Delta H_f^o = -238.7 \ kJ \ mol^{-1})$ with $2$-methylpropene produces methyl tert-butyl ether $(\Delta H_f^o = -313.6 \ kJ \ mol^{-1})$. Given the reaction: $(CH_3)_2C = CH_2 + CH_3OH \rightarrow (CH_3)_3C - OCH_3; \Delta H^o = -57.8 \ kJ \ mol^{-1}$,calculate the $\Delta H_f^o$ for $2$-methylpropene.

Which of the following reactions satisfies the following conditions?
$(a)$ Heat of combustion reaction
$(b)$ Heat of formation reaction
$(c)$ An exothermic reaction
$(d)$ Not a neutralization reaction

The net enthalpy change of a reaction is the amount of energy required to break all the bonds in reactant molecules minus the amount of energy required to form all the bonds in the product molecules. What will be the enthalpy change for the following reaction: $H_{2(g)} + Br_{2(g)} \to 2HBr_{(g)}$? Given that the bond energy of $H_2$,$Br_2$,and $HBr$ is $435 \ kJ \ mol^{-1}$,$192 \ kJ \ mol^{-1}$,and $368 \ kJ \ mol^{-1}$ respectively.

The enthalpy of solution of anhydrous $CuSO_4$ is $-15.9 \, kcal$ and that of $CuSO_4 \cdot 5H_2O$ is $2.8 \, kcal$. The enthalpy of hydration of $CuSO_4$ is ..... $kcal$. (in $.7$)