The time it takes for a full plastic bottle of cold water to freeze in a freezer can be longer than that of an empty one due to several factors:
Thermal conductivity: Water has a higher thermal conductivity than air or empty space. When the freezer cools down, the water in the bottle absorbs heat from its surroundings at a faster rate than the air in an empty bottle. This means that the water takes longer to reach the freezing temperature.
Latent heat of fusion: Water has a high specific heat capacity and a significant latent heat of fusion. Specific heat capacity refers to the amount of heat energy required to raise the temperature of a substance, while latent heat of fusion is the heat energy required to convert a substance from a liquid to a solid state (in this case, from water to ice). When the water in the bottle reaches the freezing point, it must release a significant amount of energy to change its state from liquid to solid, which further slows down the freezing process.
Insulating effect: The water in a full bottle acts as an insulating layer between the freezing air of the freezer and the core of the liquid. This insulating effect reduces the rate of heat transfer between the water and the cold air, making the freezing process slower.
Overall, these factors contribute to the longer freezing time for a full plastic bottle of cold water compared to an empty one in a freezer.