28 . 0 L of CO 2 is produced on complete combustion of 16 . 8 L gaseous mixture of ethene and methane at 25 ° C and 1 atm. Heat evolved during the combustion process is kJ Given : ΔH C CH 4 = - 900 kJ

Question

28 . 0 L of CO 2 is produced on complete combustion of 16 . 8 L gaseous mixture of ethene and methane at 25 ° C and 1 atm. Heat evolved during the combustion process is kJ Given : ΔH C CH 4 = - 900 kJ mol - 1 ΔH C C 2 H 4 = - 1400 kJ mol - 1 .

TestHub · Accepted Answer

Complete combustion of ethene and methane mixture produces carbon dioxide.
Let, Volume of $C_{2} H_{4}$ is $x$ litre

$C_{2} H_{4} + 3 O_{2} \to 2 {CO}_{2} + 2 H_{2} O$

Initial volume of carbon dioxide 0
Final volume of carbon dioxide $2 x$

${CH}_{4} + 2 O_{2} \to {CO}_{2} + 2 H_{2} O$

Initial volume of carbon dioxide is 0

Final volume of carbon dioxide is $(16.8 - x)$

Total volume of ${CO}_{2} = 2 x + 16.8 - x$

$\Rightarrow 28 = 16.8 + x$

$x = 11.2 L$

$n_{{CH}_{4}} = \frac{PV}{RT} = \frac{1 \times 5.6}{0.082 \times 298} = 0.229 mole$

$n_{C_{2} H_{4}} = \frac{11.2}{0.082 \times 298} = 0.458 mole$

$∴$ Heat evolved using standard enthalpy of combustion $= 0.229 \times 900 + 0.458 \times 1400$

$= 206.1 + 641.2$

$= 847.3 kJ$

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