Question

A gas expands in volume from 20.5m, to 98.5mt constant temperature. Calculate the work done in joules if the expands against a constant pressure of 0.75atm. 0.09511 051 5.93 -0.0585

Answer 1

As we know workdone is calculated by the formula W=-PdV (1)

P=external pressure which against expansion occurs

dV=change in volume during expansion

Due to work is done by the system,negative sign is shown here.

P=0.75 atm

final volume=98.5ml initial volume=20.5ml

change in volume=98.5-20.5=78ml=78/1000=0.078L

Putting this value in equation (1),we get W=-0.75*0.078=-0.0585atmL

1atmL = 1.01325 bar L ( $\because$ 1 atm = 1.01325 bar)

= 1.01325 × 105 pascal L( 1 bar=105 pascal )

= 101325 N/m2 × 10-3 m3 (since pascal is N/m2 and 1 L = 10-3 m3 )

= 101.325 Nm

=101.325 J

so, 1 atm liter = 101.325 J

Then -0.0585atmL*101.325 =-5.927J which is nearly equal to -5.93J

SO option 3 is correct.