Answer:
Please explain it in English so that i can help you or you need someone who can speak Vietnam help you
Answer:
The entropy change of the air is ![0.240kJ/kgK](https://tex.z-dn.net/?f=0.240kJ%2FkgK)
Explanation:
![T_{1} =427+273K,T_{1} =700K\\P_{1} =600kPa\\P_{2} =100kPa](https://tex.z-dn.net/?f=T_%7B1%7D%20%3D427%2B273K%2CT_%7B1%7D%20%3D700K%5C%5CP_%7B1%7D%20%3D600kPa%5C%5CP_%7B2%7D%20%3D100kPa)
is unknown
we can apply the following expression to find ![T_{2}](https://tex.z-dn.net/?f=T_%7B2%7D)
![-w_{out} =mc_{v} (T_{2} -T_{1} )](https://tex.z-dn.net/?f=-w_%7Bout%7D%20%3Dmc_%7Bv%7D%20%28T_%7B2%7D%20-T_%7B1%7D%20%29)
![T_{2} =T_{1} -\frac{w_{out } }{mc_{v} }](https://tex.z-dn.net/?f=T_%7B2%7D%20%3DT_%7B1%7D%20-%5Cfrac%7Bw_%7Bout%20%7D%20%7D%7Bmc_%7Bv%7D%20%7D)
now substitute
![T_{2} =700K-\frac{600kJ}{5kg*0.718kJ/kgK} \\T_{2}=533K](https://tex.z-dn.net/?f=T_%7B2%7D%20%3D700K-%5Cfrac%7B600kJ%7D%7B5kg%2A0.718kJ%2FkgK%7D%20%5C%5CT_%7B2%7D%3D533K)
To find entropy change of the air we can apply the ideal gas relationship
Δ![s_{air}](https://tex.z-dn.net/?f=s_%7Bair%7D)
![=c_{p} ln\frac{T_{2} }{T_{1} } -Rln\frac{P_{2} }{P_{1} }](https://tex.z-dn.net/?f=%3Dc_%7Bp%7D%20ln%5Cfrac%7BT_%7B2%7D%20%7D%7BT_%7B1%7D%20%7D%20-Rln%5Cfrac%7BP_%7B2%7D%20%7D%7BP_%7B1%7D%20%7D)
Δ![s_{air} =](https://tex.z-dn.net/?f=s_%7Bair%7D%20%3D)
![1.005*ln(\frac{533}{700})-0.287* in(\frac{100}{600} )](https://tex.z-dn.net/?f=1.005%2Aln%28%5Cfrac%7B533%7D%7B700%7D%29-0.287%2A%20in%28%5Cfrac%7B100%7D%7B600%7D%20%29)
Δ![s_{air} =0.240kJ/kgK](https://tex.z-dn.net/?f=s_%7Bair%7D%20%3D0.240kJ%2FkgK)
There must be a photo for me to answer!