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Four moles of an ideal diatomic gas `(gamma = 1.4)` at `300 K` and `12 atm` expanded irreversibly & adiabatically to a final pressure of `2.4 atm` against a constant pressure of `2 atm`. Calcualate `W` & `DeltaH` (magnitude only) . Report your answer as `(|X + Y|)/(10)`, where `W = X xx 10R, DeltaH = Y xx 10R` and `R` is gas constant. |
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Answer» Correct Answer - 9 `q = 0 rArr DeltaU = w` `nC_(v)(T_(2) - T_(1)) = - P_(ext.)(V_(2) - V_(1))` `C_(v)(T_(2) - 300) = -2 ((R xx T_(2))/(2.4) - (R xx 300)/(12))` `rArr (5)/(2)(T_(2) - 300) = (360)/(6) - (T_(2))/(1.2)` `5T_(2) - 1500 = 100 - (5T_(2))/(3)` `(20T_(2))/(3) = 1600 :. T_(2) = 240 K` `W = 4 xx (5R)/(2)(-60) = - 600R` `DeltaH = gammaDeltaU` or `DeltaH = (7)/(5) xx -600 R = -840 R` |
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