Why is diffusion slower in liquids than in gases?

Diffusion is slower in liquids than in gases because particles in liquids are closer together and move less freely.

In more detail, diffusion is the process by which particles spread out from an area of high concentration to an area of low concentration. This process is driven by the random motion of particles, which is influenced by the state of matter they are in. In gases, particles are far apart and move freely, allowing them to spread out quickly. This is why the smell of perfume can fill a room in a matter of seconds.

On the other hand, particles in liquids are much closer together. They are still able to move, but their movement is more restricted due to the stronger intermolecular forces between them. This means that they collide with each other more frequently, which slows down the overall rate of diffusion. For example, if you put a drop of food colouring in a glass of water, it will take a few minutes for the colour to spread throughout the water.

Furthermore, the temperature also affects the rate of diffusion. Higher temperatures increase the kinetic energy of the particles, making them move faster and therefore diffuse more quickly. However, even at the same temperature, diffusion in gases is still faster than in liquids due to the greater freedom of movement for gas particles.

In summary, the rate of diffusion is determined by the distance between particles and their freedom of movement. In liquids, the closer proximity of particles and their more restricted movement due to stronger intermolecular forces result in slower diffusion compared to gases.