For complete combustion of ethene, C _ 2 H _ 4 ( g ) + 3 O _ 2 ( g...

${C}_{2}{H}_{4} ( g ) + 3{O}_{2} ( g ) \to 2{CO}_{2} ( g ) + 2{H}_{2}O ( l )$
$\Delta U = - 1406kJ{mol}^{- 1}$

$T = 300K$

$\Delta H = \Delta U + {\Delta n}_{g}RT$

$\Delta U$ is the change in the internal energy of the system, which is the sum of the kinetic and potential energies of all the molecules in the system. $R$ is the gas constant ($8 . 314J / ( molK )$ and $T$ is the temperature in Kelvin.
$∆ H = – 1406 + ( – 2 ) \times 8 . 3 \times 300 = – 1406 – 4 . 98 = – 1410 . 98KJmol – 1 \approx – 1411TheminimumvalueofT ∆ Satequilibrium ∆ H ∆ H = T ∆ S = – 1411KJ{mol}^{– 1}$