The work done during combustion of 9 × 10-2 kg of ethane, C2H6 (g) at 300 K is ______.(Given R = 8.314 J deg-1, atomic mass C = 12, H = 1) - Chemistry

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The work done during combustion of 9 × 10-2 kg of ethane, C2H6 (g) at 300 K is ______.
(Given R = 8.314 J deg-1, atomic mass C = 12, H = 1)

Options

  • 6.236 kJ

  • - 6.236 kJ

  • 18.71 kJ

  • - 18.71 kJ

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Solution

The work done during combustion of 9 × 10-2 kg of ethane, C2H6 (g) at 300 K is 18.71 kJ.

Explanation:

Work done in a chemical reaction,

W = - ΔngRT

Where, Δng = number of moles of gaseous products - number of moles of gaseous reactants.

Reaction involved in combustion of ethane is,

\[\ce{C2H6 (g) + 7/2 O2(g) -> 2CO2(g) + 3H2O(l)}\]

∴ Δn= 2 - 4.5 = - 2.5

W = (2.5 mol)(8.314 JK-1 mol-1) × 300 K

= 6235.5 J = 6.2355 KJ

1 mole of C2H6 = 30 g of C2H

Work done during combustion of 30 g of

C2H6 = 6.2355 kJ

∴ Work done during combustion of 90 g of

C2H6 = `(6.2355 xx 90)/30` = 18.7065 kJ

= 18.71 kJ

Concept: Enthalpy (H)
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