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InterviewSolution
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The enthalpy of formation of methane at constant pressure and 300 K is – 78.84 kJ.What will be the enthalpy of formation at constant volume? |
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Answer» The equation representing the enthalpy of formation of methane is: C(S) + 2H2(g) – CH2(g) ; ∆H = – 78.84 kJ ∆U = 78.84 kJ; ∆ng = 1 – 2 = -1 mol R = 8.314 x 10-13 KJ K-1 mol-1 ; T = 300 K. According to the relation, ∆H = ∆U + ∆ng RT – 78.84 kJ ∆U = ∆H – ∆ng RT ∆U = (- 78.84 kJ) – (1 mol) x (8.314 x 10-3 KJ K-1 mol-1) x 300K. = – 78.84 – 2.49 = -8.314 KJ. |
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