If a small percentage of ammonia enters the oil, what will likely happen when the pressure on the oil is lowered?

When a small percentage of ammonia enters the oil and the pressure on the oil is lowered, the most likely outcome is that the oil will foam. This phenomenon occurs due to the reduction in pressure, which can cause the dissolved ammonia to come out of solution. As the ammonia leaves the oil, it can create bubbles, leading to foaming.

This foaming is problematic in refrigeration systems, as it can affect the lubrication properties of the oil and potentially lead to loss of efficiency or damage to the compressor. In environments where ammonia is present, managing the interactions between the ammonia and the oil is critical for maintaining system performance.

The other potential outcomes—evaporation, solidification, or separation—do not accurately take into account the behavior of ammonia in oil under reduced pressure conditions. While evaporation pertains to phase change due to temperature, solidification refers to the oil freezing under low temperatures, and separation would imply that the oil and ammonia are completely segregating, none of these address the foaming caused by the released ammonia when pressure decreases.