An industrial freezer is designed to use ammonia (NH₃)as a working fluid. The freezer is designed so that ammonia flowing through tubes inside the freezer at p− vaporizes at T = −40 ◦C, drawing heat out of the interior. Outside the freezer, the ammonia vapor at T = +45 ^◦C liquefies at a pressure p+ dumping heat into the environment. Find thermodynamic data on ammonia and identify the pressures p± that enable the liquid–vapor phase transition to take place at the required temperatures.