1. Tardigrade
  2. Question
  3. Chemistry
  4. If x1, x2 and x3 are enthalpies of H - H, O = O and O - H bonds respectively, and x4 is the enthalpy of vaporisation of water, estimate the standard enthalpy of combustion of hydrogen.

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Q. If $x_1, x_2$ and $x_3$ are enthalpies of $H - H, O = O$ and $O - H$ bonds respectively, and $x_4$ is the enthalpy of vaporisation of water, estimate the standard enthalpy of combustion of hydrogen.

Thermodynamics

Solution:

$H_{2}\left(g\right)+\frac{1}{2}O_{2}\left(g\right)\to H_{2}O\left(l\right);\Delta H_{\text{comb}} ,H_{2}$
$\Delta H_{\text{comb}}=\Delta H_{H-H}+\frac{1}{2}\Delta H_{O}
=O-2\Delta H_{O-H}-\Delta H_{\text{vap}}=x_{1}+\frac{x_{2}}{2}-2x_{3}-x_{4}$