The difference between enthalpy change and internal energy change for the combustion of one mole of ethyl…

The difference between enthalpy change and internal energy change for the combustion of one mole of ethyl alcohol is
  1. $-\frac{1}{2}$
  2. $-1.5 \mathrm{RT}$
  3. -RT
  4. $-2 \mathrm{RT}$

Solution

$\begin{aligned} & \mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}(\ell)+3 \mathrm{O}_2(\mathrm{~g}) \rightarrow 2 \mathrm{CO}_2(\mathrm{~g})+3 \mathrm{H}_2 \mathrm{O}(\ell) \\ & \Delta \mathrm{H}=\Delta \mathrm{E}+\Delta_{\mathrm{ng}} \mathrm{RT}\end{aligned}$ Here $\Delta_{\mathrm{ng}}=2-3=-1$ $\therefore \Delta H=\Delta E-R T$

Asked in: MHT CET 2022 (06 Aug Shift 1)

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