A piston-and-cylinder device contains 10 kmol of npentane at −35.5°C and 100 bar. Slowly the piston is moved until the vapor pressure of n-pentane is reached, and then further moved until 5 kmol of the n-pentane is evaporated. This complete process takes place at the constant temperature of −35.5°C. Assume n-pentane can be described by the Peng-Robinson equation of state. 

a. What is the volume change for the process? 

b. How much heat must be supplied for the process to be isothermal? 

Transcribed Image Text:

P = RT aa Vm-b V2+2bVm – b²