The formation of ammonia is shown by the reaction $N_{2(g)} + 3H_{2(g)} \to 2NH_{3(g)}, \Delta_r H^o = -91.8 \, kJ \, mol^{-1}$. What will be the enthalpy of reaction for the decomposition of $NH_3$ according to the reaction $2NH_{3(g)} \to N_{2(g)} + 3H_{2(g)}; \Delta_r H^o = ?$ ..... $kJ \, mol^{-1}$

Which of the following reactions defines $\Delta H_f^o$?

Given the following thermochemical equations:
$1) \ C_{(s)} + O_{2(g)} \rightarrow CO_{2(g)}, \Delta H = -787 \ kJ$
$2) \ H_{2(g)} + \frac{1}{2} O_{2(g)} \rightarrow H_2O_{(l)}, \Delta H = -286 \ kJ$
$3) \ C_2H_{2(g)} + \frac{5}{2} O_{2(g)} \rightarrow 2CO_{2(g)} + H_2O_{(l)}, \Delta H = -1310 \ kJ$
Calculate the enthalpy of formation of acetylene $(C_2H_{2(g)})$ in $kJ \ mol^{-1}$.

The enthalpy of formation of $NH_3$ is $-46 \ kJ \ mol^{-1}$. The enthalpy change for the reaction $2 NH_{3(g)} \longrightarrow N_{2(g)} + 3 H_{2(g)}$ is

Which of the following acids will release the maximum amount of heat when completely neutralized by a strong base $NaOH$?

Given: $2Zn + O_2 \rightarrow 2ZnO, \Delta G^o = -616 \, J$; $2Zn + S_2 \rightarrow 2ZnS, \Delta G^o = -293 \, J$; $S_2 + 2O_2 \rightarrow 2SO_2, \Delta G^o = -408 \, J$. The value of $\Delta G^o$ for the reaction $2ZnS + 3O_2 \rightarrow 2ZnO + 2SO_2$ is ....... $J$.