How much will the temperature of a cup (180 g) of coffee at 95 °c be reduced when a 45 g silver spoon (specific heat 0.24 j/g °c) at 25 °c is placed in the coffee and the two are allowed to reach the same temperature? assume that the coffee has the same density and specific heat as water.

Explanation:

There are two heat transfers involved: the heat gained by the spoon and the heat lost by the coffee.

According to the Law of Conservation of Energy, energy can neither be destroyed nor created, so the sum of these terms must be zero.

Let the spoon be Component 1 and the coffee be Component 2.

Data:  

For the spoon:

For the coffee:

Calculations

(a) The relative temperature change

The ΔT for the coffee is about 1/70 that of the spoon.

(b) Final temperature of coffee

(c) Decrease in coffee temperature