Question

A 30 X 10 X 10 cm brick is placed in a 2-m³ container along with 1 m³ of water. The container is perfectly insulated ad is immediately sealed after the brick is added. If the brick, the water, and the air in the container are originally at 50, 10, and 20C, respectively, determine the equilibrium temperature of the system. How much heat will be contained in the brick, the water, and the air before and after equilibrium? Express your results in kilocalories (kcal). Chapra (30.1)

Answer 1

The brick has a volume of 3000 cm³ (3L); no data about density or specific heat. The mass could be 10-20 kg (less than 2% in total mass)

Water (1000 kg here) is known to have a high t specific heat 4.18 J/g.^oC,   higher that for any other common substance.

The air is about 1000 L/ 22.4 l/mol x 28.9 g/mol = 760 g, less than 1% in total mass.

A rough increase of the temperature can be estimated to be less than 1^oC or even less. Consider also the low precision in measuring the temperature (+/_ 1 ^oC).

1. The equilibrium temperature of the system will be close to the initial temperature of water (10^oC).
2. The system is isolated, thus the same heat will be contained before and after the equilibrium.