Question

An 8-L cylinder contains air at 300 kPa and 300 K. Now air is compressed isothermally to a volume of 2 L. The work done on air during this compression process is: (b) 1.8 kJ (c) 3.3 kJ (a) 119 kJ (d) 4.5 kJ

Answer 1

Answer:

W=3.327 KJ

Explanation:

Given that

$P_1=300 KPa,V_1=8 L$

$V_2=2 L$

Temperature remains constant it means that this is isothermal process

For isothermal process$P_1V_1=P_2V_2$

We know that work for isothermal process  

$W=P_1V_1\ln \dfrac{P_1}{P_2}$

$W=P_1V_1\ln \dfrac{V_2}{V_1}$

Now by putting the values

$W=300\times 8\times 10^{-3}\ln \dfrac{2}{8}$

W=-3.327 KJ

Negative sign indicates is process is compression

W=3.327 KJ

So our option C is right.