How much hot water with a total temperature of 65 ° C was if, when 2 kg of cold water with a temperature

How much hot water with a total temperature of 65 ° C was if, when 2 kg of cold water with a temperature of 5 ° C was added to it, the temperature of the mixture became equal to 45 ° C

Initial data: t1 (hot water temperature) = 65 ºС; m2 (mass of added cold water) = 2 kg; t2 (cold water temperature) = 5 ºС; t (steady water temperature) = 45 ºС.

The mass of hot water is determined from the heat balance equation: Q1 = Q2.

C * m1 * (t1 – t) = C * m2 * (t – t2).

m1 = m2 * (t – t2) / (t1 – t).

Let’s calculate: m1 = 2 * (45 – 5) / (65 – 45) = 2 * 40/20 = 4 kg.

Answer: The mass of hot water was 4 kilograms.