InterviewSolution
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InterviewSolution
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Calculate the amount of work done in each of the following cases `:-` (i) One mole of an ideal gas contained in a bulbof 10 litre capacity at 1 bar is allowed to enter into an evacuated bulb of 100 litre capacity. (ii) One mole of a gas is allowed to expand from a volumeof 1 litre to a volume of 5 litres against the constant external pressure of 1 bar ( 1 litre bar = 100 J) Calculate the internal energy change `(Delta U ) ` in each case if the process were carrid out adiabatically. |
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Answer» (i) `x= -P_(ext)xxDeltaV` As expansion takes place into the evacuated bulb, i.e., agains vacuum, `P_(ext) = 0`. Hence, w`=` 0 For adiabatic process `, q=0 :. Delta U = q+w= 0+0=0` (ii) `Delta V = V_(2)-v_(1) =5-1 = 4 `litres `P= 1`bar` :. w= - P Delta V = -1 xx 4` litre bar `= - 4 xx 100J = -400J ( 1 L ` bar `= 100 J )` The negative sign implies that the work is done by the system. For adiabatic process, `q=0` . Hence `Delta U = q+w= 0 - 405.2 J = - 405 . 2 J`. |
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