Question

The heat of formation of ${H_2O_{(l)}}$ is -286 kJ. The? heat of formation of ${ H_2O_{(g)}}$ is likely to be

• A. - 286 kJ
• B. +286 kJ
• C. - 341 kJ
• D. - 242.8 kJ

Answer 1

Answer: (D)

- 242.8 kJ

Answer 2

The enthalpy of ${H_2O_{(l)}}$ is less than that of ${H_2O_{(g)}}$, hence more energy will be released when ${H_2O_{(l)}}$ is formed.
$\Rightarrow \:\: \Delta H_f {H_2O_{(g)}} < \Delta H_f {H_2O_{(l)}}$