Separating substances from each other can be a difficult problem. But you're used to tricky problems in science, aren't you?

However, there are certain 'rules' that actually help you to make sense of how substances should be separated.

Like, if you've mixed two things in water, one which dissolves and the other doesn't, then you can always get them apart by filtering (like a very fine sieve).

Similarly, if you want to get the dissolved substance back out of the water, you simply evaporate the water away.

Hopefully, those are processes that you're familiar with as you've used them before.

Let's practise some of these ideas and see how you get on.