Question

Oxygen gas in a piston cylinder at 300 K, 100 kPa with volume 0.1 m3 is compressed in a reversible adiabatic process to a final temperature of 700 K. Find the final pressure and volume.

Answer 1

C.V. Air. Assume a reversible, adiabatic process.

Energy Eq   u₂ - u₁ = 0 − ₁w₂ ;

Entropy Eq  s₂ - s₁ = ∫ dq/T + 1s₂ gen = 0

Process: Adiabatic ₁q₂ = 0 Reversible ₁s₂ gen = 0

Properties: k = 1.393

With these two terms zero we have a zero for the entropy change. So this is a constant s (isentropic) expansion process. 

P₂ = P₁( T₂ / T₁) ^k/k-1 = 2015 kPa

Using the ideal gas law to eliminate P from this equation leads