We learned about the Graham’s Law which is diffusion and effusion. Definition of diffusion is the tendency of molecules to move toward areas of lower concentration until it ùiorm throughout. Perfume can be an example, when you open the perfume bottle, we can be able to smell, the molecules in perfume can evaporate and diffuse, which like spreading out through the air in the room. Another process involves movement of molecules is effusion, which is like a gas that can escape through a small hole in its container. The rate of effusion of a gas is inversely proportional. The gas of lower mass can diffuse and effuse faster than gas of higher molar mass. How fast it moves, it depends on the molar mass.