All Problems

Second law of thermodynamics, entropy

Problem 2.133

Helium of mass \(m=1.7 \mathrm{~g}\) is expanded adiabatically \(n=3.0\) times and then compressed isobarically down to the initial volume. Find the entropy increment of the gas in this process.

Reveal Answer
ΔS=mMγRγ1lnn=10 J/K\Delta S=-\frac{m}{M} \frac{\gamma R}{\gamma-1} \ln n=-10 \mathrm{~J} / \mathrm{K}