Question

280 millimol of perfect gas occupies 12.7 at 310 K. Calculate work done when gas expand isothermally against constant external pressure of 0.25 atm? isothermally and reversibily?adiabatically? untill its volume become 3.3 L.

• A. -83.6
• B. 166.9
• C. 0
• D. all are currect

Answer 1

The correct option is D all are currect

(a) The gas expand isothermally against constant pressure of $0.25$ atm,

$W=-P_{ext}\times \Delta V=0.25$ atm$\times 3.3L=-0.825L.atm$

$=-83.6J$

(b) Gas expands isothermally and reversibly,

$V_2=3.3+12.7=16L$

$W_{max}=-2.303\times 0.28\times 8.314\times 310\times \log \frac{16}{12.7}$

$=166.9J$

(c) Gas expands adiabatically. In this case it is a free expansion, there is no opposing pressure.

$\therefore P_{ext}=0$

$\therefore W=0$