Question

What creates gas pressure in a container such as a helium balloon?

Answer 1

The kinetic theory of gas states that gas particles are always moving with different speeds in random directions and while covering the path of movement they collide with each other. The collision of molecules with walls of containers exerts pressure.

Complete answer:
Gases have very different properties than other states of matter. A gas expands to fill the shape and volume of its container. Also, gases can be compressed into a small container.
Kinetic-molecular theory of gases states that the gas particles move randomly and in straight lines until they elastically collide with other gas particles or with the walls of the container. Due to these collisions with the walls of the container, pressure is exerted by the gas in the container.
Four state variables are used to describe the condition of a gas. They are pressure (P), volume (V), temperature (T), and the amount of the gas, that is, the number of moles (n). each term is related to another. The dependence of pressure on each variable is stated below –
- An increase in the number of gas molecules in the same volume container increases pressure.
- A decrease in container volume increases gas pressure.
- An increase in temperature of a gas in a rigid container increases the pressure.
Hence, the gas pressure in a container such as a helium balloon arises from the impact of the collisions of the helium atoms between themselves and with the inside surface of the balloon.

Note:
The outside atmosphere of the balloon similarly exerts a pressure on its outer surface. However, since the density of helium gas is greater than the density of air, the volume inside the balloon expands with respect to the atmosphere and the balloon inflates.