How much boiling water needs to be added to a vessel containing 2 kg of water

How much boiling water needs to be added to a vessel containing 2 kg of water at a temperature of 35 so that the temperature in the vessel increases to 65.

To find the mass of boiling water poured into the vessel under consideration, we use the equality: C * mk * (tk – tp) = Q (thermal energy) = C * mt * (tr – tt), whence we express: mk = mt * (tr – tt) / (tк – tр).

Values of variables and constants: m is the mass of warm water in the vessel (mt = 2 kg); tр – equilibrium temperature (tр = 65 ºС); tт – temperature of warm water (tт = 35 ºС); tк – boiling water temperature (tк = 100 ºС).

Calculation: mk = mt * (tp – tt) / (tk – tp) = 2 * (65 – 35) / (100 – 65) = 1.714 kg.