Principle

Different amounts of hot and cold water are mixed. The hot water
is always poured into a calorimeter containing cold water (room
temperature). This has the following advantage: the cold water
defines the temperature of the calorimeter; and since the hot water
is poured in, the mix temperature is the largest value which is
found in every case. The emergence of a mix temperature is first
qualitatively explained. In the supplementary problem the equation
for the mix temperature is given. The comparison of the calculated
and measured values shows that the heat capacity of the calorimeter
must still be considered.