What is the state of ammonia at -32°F and 3" Hg?

The state of ammonia at -32°F and 3 inches of mercury (Hg) is classified as saturated (SAT) because these conditions are close to its boiling point under the given pressure. At lower pressures, the boiling point of ammonia decreases significantly, and as the pressure drops to around 3 inches of mercury, the ammonia is likely to be near its saturation temperature, which means it exists in equilibrium as both liquid and vapor.

In this context, saturation refers to the state in which both liquid and vapor phases are present at a specific temperature and pressure, and substances are recognized as saturated when they are at their boiling point. Since the temperature is below the vaporization point under low pressure, ammonia does not enter a state of superheating or sub-cooling. Superheated states exist when a vapor is at a temperature higher than its boiling point at a given pressure, while sub-cooled states are when a liquid is below its boiling point at a certain pressure. The trans-critical state would involve conditions that lead to a distinct phase behavior that does not apply at the conditions given in this scenario.

Thus, the condition of ammonia at -32°F and 3 inches of mercury is appropriately identified as saturated.