The standard enthalpy of formation of liquid water at $25^{\circ} C$ is approximately:
$H_{2(g)} + \frac{1}{2} O_{2(g)} \longrightarrow H_2O_{(l)}$

Given the bond energies of $N \equiv N$,$H - H$ and $N - H$ bonds are $945$,$436$ and $391 \ kJ \cdot mol^{-1}$ respectively,the enthalpy of the following reaction $N_{2(g)} + 3H_{2(g)} \to 2NH_{3(g)}$ is ...... $kJ$.

Combustion of glucose takes place according to the equation,$C_6H_{12}O_6 + 6O_2 \to 6CO_2 + 6H_2O$,$\Delta H = -72 \ kcal$. How much energy will be required for the production of $1.6 \ g$ of glucose? (Molecular mass of glucose $= 180 \ g/mol$)

Calculate the enthalpy change when $12 \ g$ of carbon reacts with sufficient hydrogen to form methane. If the enthalpy of formation of methane is $-75 \ kJ \ mol^{-1}$. (in $kJ$)

The atomisation enthalpy of $CH_4$ is $1660 \ kJ \ mol^{-1}$. The $C-H$ bond enthalpy of each successive step in $CH_4$ $\rightarrow CH_3$ $\rightarrow CH_2$ $\rightarrow CH$ are $+15, +30$ and $+45 \ kJ \ mol^{-1}$ higher than the mean bond enthalpy of $C-H$ bonds,respectively. The bond enthalpy of the last $C-H$ unit is

The heat of formation of water is $260 \ kJ$. How much $H_2O$ is decomposed by $130 \ kJ$ of heat (in $mol$)?