Question
An ideal gas undergoes a process from state 1 (T1 = 300 K,p1 = 100 kPa) to state 2 T (T2 = 600 K,p2 = 500 kPa) . The specific heats of the ideal gas are: cp = 1 kJ/kg-K and Cv = 0.7 kJ/kg-K. The change in specific entropy of the ideal gas from state 1 to state 2 (in kJ/kg-K) is ________ (correct to two decimal places)
Answer :
0.21
Ideal gas
State-1: T1= 300 K, P1 = 100 kPa
State-2: T2= 600 K, P2= 500 kPa
cp, = 1 kJ/kg-K, cp - cv = R, cv, = 0.7 kJ/kg-K
cp - cv= 1-0.7 = R
R = 0.3 kJ/kg-K
Change in specific entropy
s2-s1 = cplnT2/T1 - RlnP2/P1
= 1*ln(600/300) -0.3ln(500/100) = 0.21 kJ/kg-K
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