Question

Question #85d5a

Answer 1

Because this would be taking water through a phase transition....

Explanation:

There is an inherent difference between increasing the temperature of water from `14.5^oC` to `15.5^oC` and increasing it from `0^oC` to `1^oC`. In the former case, you are simply supplying sufficient energy to raise the temperature of a liquid, whilst in the latter case you are first needing to supply sufficient energy to overcome the crystal structure of ice, and then to raise the temperature of the resulting liquid to `1^oC`.

To remove any effects caused by the phase transition, it was decided to use a pure temperature increase in a single phase (liquid).