Final answer:
As water freezes or evaporates, the salinity of the remaining ocean water increases. This is due to the separation of pure water molecules from the dissolved ions during both evaporation and the crystallization process of freezing, leaving behind a higher concentration of salts in the water.
Step-by-step explanation:
When water freezes or evaporates, the salinity of the remaining ocean water increases. During the process of evaporation, only the water molecules transition from a liquid state to gas and subsequently condense to form clouds, leaving the dissolved ions like salt behind. This concentration effect also occurs when water freezes. Ice crystallizes and incorporates very little of the dissolved salts, thus also leaving behind more concentrated salty water.
In the context of desalination, one can observe how these natural processes of phase change can separate the water from its dissolved substances. While the evaporative process is a distillation that produces almost pure water, the freezing process excludes salts from the solid ice phase. As a result, methods such as evaporation, condensation, and freezing are employed to purify water and reduce its salinity.
Moreover, in temperature dynamics during the freezing of water, the heat released keeps the temperature steady at the melting point while the rest of the water turns into ice. This phenomenon has implications for the thermodynamic properties of water and how such changes affect the surrounding environment.