Question

In hot water bottles, water is used primarily because
A. Its specific heat is low
B. Its specific heat is high
C. It is cheap
D. It is easily available

Answer 1

Water is said to be used as a universal coolant because of its ability to show a minor change in temperature even after taking in large amounts of heat. The concept of specific heat of water needs to be applied in order to find out why water is used in hot water bottles. The principle behind hot water bottles is that they are said to retain the heat of the water in the water bottles.

Complete answer:
In order to know why water is used in hot water bottles we first need to know what the specific heat capacity of a material refers to. The specific heat of a material specifies the amount of heat energy required to raise the temperature of a substance per unit of mass. It is the heat required to raise the temperature of a $1g$ sample by a temperature of $1K$ or $1{}^ \circ C$ .

The reason why water is used in hot water bottles is because it is said to have a high specific heat capacity. The specific heat capacity refers to a measure of how much heat is absorbed by the body. Water is said to be a substance which requires a large amount of energy to produce a change in its temperature by a small amount. This means that water takes in a lot of energy in order to heat up.

For water to heat up and boil the bonds between its molecules must be broken in order for them to gain kinetic energy and then escape the surface of water as vapor. The main reason for the specific heat of water to be so high is because of the strength between its molecules which are said to be extremely strong.

The intermolecular force between the molecules of water is high because atoms and molecules of water are connected by the hydrogen bonds. Hydrogen bonds are known to be the strongest among all the types of intermolecular forces. Due to the presence of strong hydrogen bonding between its molecules a high amount of energy is required in order to break these bonds. Hence, water is said to have a high specific heat capacity.

In hot water bottles, water is used and due to its high specific heat the water remains warm for a longer period of time and this is the concept and the purpose behind a hot water bottle. Thus, in hot water bottles, water is used primarily because its specific heat capacity is high.

Therefore, the correct answer is option B.

Note: Hot water bottles exhibit the same principle as the thermos flask and hence consist of a stopper as part of its construction so that the water is not vaporized and so that the heat is retained inside it. Hot water bottles are also used for the purpose of fermentation as well due to its high specific heat capacity.