Some vapor pressure data for Freon-12, CCl₂F₂, once a common refrigerant, are -12.2 °C, 2.0 atm; 16.1 °C, 5.0 atm; 42.4 °C, 10.0 atm; 74.0 °C, 20.0 atm. Also, bp = -29.8 °C, T_c = 111.5 °C, P_c = 39.6 atm. Use these data to plot the vapor pressure curve of Freon-12. What approximate pressure would be required in the compressor of a refrigeration system to convert Freon-12 vapor to liquid at 25.0 °C?