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**Problem statement:**

A sample of 8.02 × 10

^{-1}moles of nitrogen gas ( γ = 1.40) occupies a volume of 2.00 × 10

^{-2}m

^{3}at a pressure of 1.00 × 10

^{5}Pa and temperature of 300 K. It is isothermally compressed to half its original volume. It behaves like an ideal gas. Find the change in entropy of the gas.

**Relevant equations:**

S

_{2}-S

_{1}= Cv log

_{e}(P

_{2}/ P

_{1}) + Cp log

_{e}(V

_{2}/ V

_{1})

S

_{2}-S

_{1}= Cv log

_{e}((P

_{2}V

_{2}

^{γ}) / (P

_{1}V

_{1}

^{γ}))

PV=nRT

**Attempt at answer:**

V

_{2}= 1.00 x 10

^{-2}m

^{3}

P

_{2}can be found by P = nRT / V = 2.00 x 10

^{5}Pa

I assume Cv must be worked out from γ somehow, but I cannot see how to do this.

Thanks in advance for your help guys!