GATE 2017 ME (ME2) – Question 54
One kg of ideal gas, R = 287 J/kg K, undergoes an irreversible process from 1 bar, 300 K to 2 bar, 300 K. Its specific entropy change is ______ J/kg K.
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: -201 to -197
Explanation
Entropy is a state property even for an irreversible path. For an ideal gas, Δs=cp ln(T2/T1)−R ln(p2/p1). The temperature term is zero, giving−287 ln2=**−198.93J/(kg·K)**. Negative gas entropy change does not imply negative total entropy generation.