effusion
Effusion is the process by which gas molecules escape from a container through a small opening into a vacuum or less dense area. This phenomenon occurs because gas molecules are in constant motion and can pass through tiny holes, allowing them to spread out and fill available space. The rate of effusion depends on factors such as the size of the gas molecules and the temperature of the environment.
A common example of effusion is seen with helium balloons. Over time, the helium gas inside the balloon escapes through tiny pores in the material, causing the balloon to deflate. This process illustrates how gases can move from areas of higher concentration to lower concentration, demonstrating the principles of gas behavior.