Question

What happens to the volume of a substance when the temperature increases?

Answer 1

Hint : When the temperature of a substance increases it changes phases. If a solid is heated it turns into a liquid and further temperature increases turn into gas/vapour. The relationship between volume and temperature is explained in Charles’ Gas Law.

Complete Step By Step Answer:
Charles’ Law states that if the pressure (P) and amount of gas (n) are constant then the volume and temperature are directly proportional to each other.
If the temperature in Kelvin is increased, the volume of the gas increases. Similarly, if the temperature is decreased the volume of the gas decreases. Both the conditions occur when P and n are constant.
This defines that the volume of the gas is directly proportional to the temperature in Kelvin. It is shown by the formula:
$\dfrac{{{V}_{1}}}{{{T}_{1}}}=\dfrac{{{V}_{2}}}{{{T}_{2}}}$
As for the solids and liquids, when the temperature increases the molecules gain energy and start moving in all directions. This expands the substance and the volume of the substance increases.
We know that,
$Density\text{ }=\text{ }\dfrac{Mass}{Volume}$
If the temperature increases the density of the substance decreases, which eventually decreases the volume.
In solids temperature change hardly changes the density so there is negligible volume change. whereas in liquids and gases the increase in temperature changes the density which increases the volume considerably.
Final answer: The volume of a substance increases when the temperature increases.

Note :
Temperature also affects the motion of the molecules in the liquid. The increase in temperature of the solid, liquid, or gas makes the particles move more rapidly. As soon as the temperature is lowered, the particles of the substance slow down.