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प्रश्न
\[\ce{∆_f U^Θ}\] of formation of \[\ce{CH4 (g)}\] at certain temperature is – 393 kJ mol–1. The value of \[\ce{∆_f H^Θ}\] is ______.
पर्याय
zero
\[\ce{< ∆_f U^Θ}\]
\[\ce{> ∆_f U^Θ}\]
equal to \[\ce{∆_f U^Θ}\]
उत्तर
\[\ce{∆_f U^Θ}\] of formation of \[\ce{CH4 (g)}\] at certain temperature is – 393 kJ mol–1. The value of \[\ce{∆_f H^Θ}\] is \[\ce{< ∆_f U^Θ}\].
Explanation:
The balanced equation for the combustion of methane is
\[\ce{CH4 (g) + 2O2 (g) -> CO2 (g) + 2H2O (l)}\]
Therefore, `∆n_g = 1 - 3 = - 2`
\[\ce{∆H_o = ∆U_o + ∆ng}\] RT
\[\ce{∆H_o = - 393 - 2}\] RT
∴ \[\ce{∆H_o < ∆U_o}\]
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