The spring unwinds as the piston moves down and the

Question

An insulated vertical piston-cylinder device initially contains 0.8 m³ of refrigerant-134a at 1.4 MPa and 120°C. A linear spring at this point applies full force to the piston. A valve connected to the cylinder is now opened, and refrigerant is allowed to escape. The spring unwinds as the piston moves down, and the pressure and volume drop to 0.7 MPa and 0.5 m³ at the end of the process. Determine

(a) the amount of refrigerant that has escaped and

(b) the final temperature of the refrigerant.