Dilution
Dilution is the reduction of concentration in a solution.
Showing Dilution and Leading to the Idea of Small Sized Particles
Suppose you dissolve 0.1g of potassium manganate (VII) in 10cm3 of water to give a deep purple solution. Assume the smallest drop you can see is 1/1000cm3. The whole solution will be made up of 10000 drops, each drop containing 0.00001g of potassium manganate (VII).
Suppose you dilute this down 10 times by taking 1cm3 of the solution and making it up to 10cm3 with more water. Continue doing this until the colour is too faint to see. By the time of the fifth dilution, each drop will only contain a billionth of a gram of potassium manganate (VII). If you only needed one ‘particle’ of potassium manganate (VII) per drop in order to see the colour, the ‘particle’ can’t weigh more than a billionth of a gram.
IS this a good answer? Nowhere near it! A potassium manganate (VII) particle actually weighs about 0.00000000000000000000026g! In reality, you need huge numbers of particles in each drop in order to see the colour.
Don’t worry I don’t get this either…