A 35.0-g iron rod, initially at 25.6°C, is submerged into an unknown mass of water at 67.7°C, in an insulated container. The final temperature of the mixture upon reaching thermal equilibrium is 63.5°C. What is the mass of the water?

Answer 1

[mass rod x specific heat rod x (Tfinal-Tintial)] + [mass H2O x specific heat H2O x (Tfinal-Tinitial)] = 0
Substitute and solve for the only unknown, mass H2O.

Answer 2

28.014 g