Why does the refrigerant in the condenser change state from vapor to liquid?

The refrigerant in the condenser changes state from vapor to liquid primarily because it loses heat energy to the surrounding environment. When the vapor refrigerant enters the condenser, it is at a higher temperature and pressure. As it passes through the condenser coils, it comes into contact with a cooler environment—typically air or water—that facilitates this heat exchange.

As the refrigerant loses heat to the surrounding environment, its thermal energy decreases, which allows the refrigerant molecules to come closer together. This release of heat causes the refrigerant to condense from a gaseous state into a liquid state. The efficiency of this process is crucial in the refrigeration cycle, as it prepares the refrigerant for the next stage, typically the expansion valve, where it will undergo a pressure drop and further cool down before entering the evaporator.

The other options, such as absorbing heat or suggesting that the refrigerant does not change state, do not accurately describe the fundamental operation of the condenser in a refrigeration system. The key process that enables the refrigerant to transition from vapor to liquid is indeed the loss of heat energy.