Question

A gas undergoes an isothermal expansion form V_1 = 3.7L followed by isobaric p = cst compression. If p_1 = 2.8atm, p_2 = 1.5atm Rightarrow ? N/m^2, calculate the work done by gas during the expansion.

Answer 1

Since for isothermal process,

PV=nRT for n moles of gas

$P_1V_1=nRT$

T is same throughout isothermal process

$V_1=3.7L=3.7*10^{-3}m^3$

so $nRT=P_1V_1=283710*3.7*10^{-3}=1049.727J$

so work done during isothermal expansion

$W=nRT ln\frac{V_2}{V_1}=nRT ln\frac{P_1}{P_2}$

$W=1049.727 ln\frac{2.8}{1.5}=1049.727 *2.303 log_{10} \left (\frac{2.8}{1.5} \right )$

$W=1049.727*2.303*0.27=652.73J$