Question

The specific heat capacity of water is:
A.1 calorie ${g^{ - 1}}$
B.10 calorie ${g^{ - 1}}$
C.2 calorie ${g^{ - 1}}$
D.30 calorie ${g^{ - 1}}$

Answer 1

Specific heat $\left( {{C_p}} \right)$ is the amount of heat required to change the heat content of 1 gram of an material by ${1^ \circ }C$. When two materials, each initially at different temperatures are placed in contact with one another, heat always flows from the warmer material to the colder material until both the materials attain the same temperature. From the law of conservation of energy, the heat gained by the initially cold material should be equal to the heat lost by the initially warmer material.

Complete step by step answer:
For a liquid at room temperature and pressure, the value of specific heat capacity $\left( {{C_p}} \right)$ is approximately $4.2\,J/{g^ \circ }C$. This implies that it takes 4.2 joules of energy to raise 1 gram of water by 1 degree Celsius.
The specific heat capacity of water is 1 calorie ${g^{ - 1}}$ (4182 $J/k{g^ \circ }C$) . It has the highest heat capacity because it requires more energy to raise the temperature.
Hence, the correct option is (A).

Note:
We can explain the reason for the high specific heat of water due to the hydrogen bonds. To increase the temperature of the water with the multitude of joined hydrogen bonds, the molecules have to vibrate. Due to the presence of so many hydrogen bonds, a larger amount of energy is required to make the water molecules break by vibrating them.
Similarly, for hot water to cool down, it takes a bit of time. As heat is dissipated, temperature decreases, and the vibrational movement of water molecules slows down. The heat that is given off counteracts the cooling effect of the loss of heat from the liquid water.