When 86.7 g of water at a temperature of 73 °C is mixed with an unknown mass of water at a temperature of 22.3 °C the final temperature of the resulting mixture is 61.7 °C. What was the mass of the second sample of water?

Question

(Specific heat of water 4.184 J·g-1·°C-1)

Answer 1

loss of heat warm water + gain of heat cold water = 0

[mass warm H2O x specific heat H2O x (Tfinal-Tinitial)] + [mass cool H2O x specific heat H2O x (Tfinal-Tinitial)] = 0
Substitute and solve for mass cool water.