Final answer:
The chosen temperature of 20°C is likely because it's close to standard room temperature, making it a controlled reference point for experiments. In calorimetry, water's high specific heat means the final temperature after heat exchange is closer to water's temperature.
Step-by-step explanation:
The chosen temperature of 20°C for an experiment can be suggested because this temperature is close to room temperature, which is a standard reference point. It's often used as a starting point for experiments because it's convenient and represents a controlled environment.
Additionally, in the context of a calorimetry problem, the specific heat of water plays a crucial role, as water has a high capacity to absorb heat with minimal changes in its own temperature. So, when two bodies at different temperatures come into contact, the final temperature will be closer to the temperature of the substance with the higher specific heat capacity, which in this case, is water.
For instance, when 0.0100 kg of 20.0°C water is poured onto a 1.20-kg block of ice at -15.0°C, the final temperature after heat exchange will be closer to the water's initial temperature due to water's higher specific heat capacity. This explains why a large body of water, such as a lake, has a more consistent temperature compared to the surrounding air despite daily temperature fluctuations. However, over longer periods, such as seasons, the temperature of the lake does change significantly.