An insulated rigid tank of volume 8 m3 initially contains air at 600 kPa and 400 K. A valve connected to the tank is opened, and air escapes until the pressure inside the tank is 200 kPa. The air temperature during the release is kept constant using an electrical resistance heater in the tank. What is the amount of work done by the resistance heater (Wcv) during the process

Question

Engineering

Glenn Goodwin

6 June, 03:10

An insulated rigid tank of volume 8 m3 initially contains air at 600 kPa and 400 K. A valve connected to the tank is opened, and air escapes until the pressure inside the tank is 200 kPa. The air temperature during the release is kept constant using an electrical resistance heater in the tank. What is the amount of work done by the resistance heater (Wcv) during the process

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Devan Martin · Answer 1

The work done is 3654.83 J/mol

Explanation:

The process is an isothermal process since the air temperature is kept constant during the release.

W = RT ln (P1/P2)

R is gas constant = 8.314 J/mol. K

T is air temperature = 400 K

P1 is initial pressure of air = 600 kPa

P2 is final temperature of air = 200 kPa

W = 8.314*400 ln (600/200) = 3325.6*ln 3 = 3325.6*1.099 = 3654.83 J/mol