Question

What causes pressure in a closed container of gas?

Answer 1

Hint: This question can be solved by observing the movement of gas particles in a container. The relation between pressure and the particles is given by the gas law and it can further be used to understand the nature of the gas.

Complete answer:
In a closed container, the molecules of gas expand to fill up space. They are in constant motion and keep their distance from each other. Unless they come in contact with another object and collide with the other molecules and the walls of the container, they move in a single direction.
When molecules of gas come in contact with either each other or with the walls of the container, they exert pressure. Since they cannot escape the container, they bounce around and strike the inside wall of the container.
Now, the pressure of a gas in a closed container depends upon the following factors:
1. Density of the gas
When the density of the gas is increased, the number of molecules (N) inside the container also increases. This results in an increase in the number of collisions and hence the pressure within the system increases.
\[P\propto N\]
2. Temperature
When there is an increase in the temperature of the container, the kinetic energy of the molecules of the gas increases. Due to this increase in kinetic energy, the movement of the gas molecules increases. And hence the pressure increased.
\[P\propto T\]
3. Volume
When the volume a gas occupies is decreased, the pressure increases. This is because the gas molecules are forced to be closer. Since their movement continues, the distance needed to travel to impact the container decreases and collusions increase hence increasing pressure.
\[P\propto \dfrac{1}{V}\]
Hence, the above-mentioned factors cause and influence the pressure in a closed container of gas.

Note:
It should be noted that the ideal gas law equation can be used to define the relationship between pressure and the effects of the number of molecules, volume, and temperature.
PV = nRT
Where the number of moles of gas present is n and the gas constant is R.