What is the final equilibrium temperature when 12 g of milk at 7◦C is added to 175 g of coffee at 69◦C? Assume the specific heats of milk and coffee are the same as that of water, and neglect the specific heat of the container. Answer in units of ◦C.

65.1 degree C

Explanation:

mass of milk, m1 = 12 g

T1 = 7 degree C

mass of coffee, m2 = 175 g

T2 = 69 degree C

Let T be the equilibrium temperature.

According to the principle of calorimetery

Heat lost by hot body = heat gained by cold body

mass of coffee x specific heat of coffee x decrease in temperature = mass of milk x specific heat of milk x rise in temperature

175 x c x (69 - T) = 12 x c x (T - 7)

12075 - 175 T = 12 T - 98

12173 = 187 T

T = 65.1 degree C