MCQ
In which case change in entropy is negative ?
- AEvaporation of water
- BExpansion of a gas at constant temperature
- CSublimation of solid to gas
- ✓$2H(g)\rightarrow H_2(g)$
Due to bond formation, entropy decreases
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| $H - H$ bond energy | $:\, 431.37 \,kJ\, mol^{-1}$ |
| $C= C$ bond energy | $:\, 606.10\, kJ \,mol^{-1}$ |
| $C - C$ bond energy | $:\, 336.49\, kJ\, mol^{-1}$ |
| $C - H$ bond energy | $:\, 410.50\, kJ\, mol^{-1}$ |
Enthalpy for the reaction,
$\begin{array}{*{20}{c}}
{H\,\,\,\,H} \\
{|\,\,\,\,\,\,\,\,|} \\
{C = C} \\
{|\,\,\,\,\,\,\,\,\,|} \\
{H\,\,\,\,H}
\end{array}\, + \,H - H\, \to \,\begin{array}{*{20}{c}}
{H\,\,\,\,H} \\
{|\,\,\,\,\,\,\,\,|} \\
{H - C - C - H} \\
{|\,\,\,\,\,\,\,\,\,|} \\
{H\,\,\,\,H}
\end{array}\,$
will be .............. $\mathrm{kJ \,mol}^{-1}$