1.3 understand how the results of experiments involving the dilution of coloured solutions and diffusion of gases can be explained

Osmosis: Water particles have a kinetic energy which allows them to bounce off of each other and mix with the particles of the coloured solution. Eventually the coloured solution will be evenly dispersed throughout the water, diluting it and making the water turn the colour of the dye.

Osmosis is the movement of water from a less concentrated solution to a more concentrated solution through a partially permeable membrane.

Diffusion: Gas particles have a high kinetic energy which allows them to bounce off each other and disperse throughout the air, mixing with other particles. eg. the spreading of the scent of perfume through the air

Diffusion is the spreading of particles from an area of high concentration to an area of low concentration.