Question

2 kg of air in a piston cylinder system is compressed isothermally at 27 deg C. If the initial pressure is 100 kPa and the final volume is one third of the initial volume, find the change in entropy.

Answer 1

The change in entropy = -0.6306 kJ/k

Step-by-step explanation:

The mass of air = 2kg

In a Compressed isothermal process T₁ = T₂ = 27⁰ C

The initial pressure = 100 kPa

Final volume V₂ = 1/3 (V₁)

i.e. V₂/V₁ = 1/3

Rate ( gas constant) R = 0.287 kJ/kgk

The change in an entropy process is:

ΔS = m × R × In(V₂/V₁)

ΔS = 2 × 0,287 × In (1/3)

ΔS = -0.6306 kJ/k