A professor orders 250 mL of house coffee at precisely 95°C. She then adds enough milk at 10°C to drop the temperature of the coffee to exactly 90° C.

Question

Calculate the amount of milk (in mL) the professor must add to reach this temperature. Assume that the coffee and milk have the same specific heat capacity: 4.184 J/(g × °C). Assume that they also have the same density: 1.0 g/mL.

Answer 1

mass in grams = mL milk
mass in grams = mL coffee
heat lost by coffee + heat gained by milk = 0

[mass coffee x specific heat coffee x (Tfinal-Tinitial)] + [mass milk x specific heat milk x (Tfinal-Tinitial)] = 0
Substitute the numbers and solve for mass milk in grams which = mL milk.

Answer 2

34

Answer 3

41.8

Answer 4

19.3