QJEEM22Ch0f51: JEE Main 2022 Chemistry - Class 11 JEEM22Ch0f51 Solution: At 25 C and 1 atm pressure, the enthalpies of combustion are as …

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At 25 $^\circ$ C and 1 atm pressure, the enthalpies of combustion are as given below :

Substance	${H_2}$	C (graphite)	${C_2}{H_6}(g)$
${{{\Delta _c}{H^\Theta }} \over {kJ\,mo{l^{ - 1}}}}$	$- 286.0$	$- 394.0$	$- 1560.0$

The enthalpy of formation of ethane is

Accepted Answer

2 \mathrm{C}

(graphite)

+3 \mathrm{H}_{2}(\mathrm{~g}) \rightarrow \mathrm{C}_{2} \mathrm{H}_{6}(\mathrm{~g})

\Delta \mathrm{H}_{\mathrm{r}}=+1560+2(-394)+3(-286)

=-86.0 \mathrm{~kJ} \mathrm{~mol}^{-1}

Enthalpy of formation of C₂H₆(g) = –86.0 kJ mol–1

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