The filtered liquid is called the filtrate. The larger solid particles, in this case, the sand grains are unable to pass through and are left on the paper. And we call this the residue. Sometimes, near the top of the glass, the water particles will be going fast enough to escape into the air. You might like to add spots of some pure coloured pigments alongside it, so that you can see if they are present in the mixture. Gethin : I got all excited because I thought Miss Armit brought in sweets and balloons for a bit of a party. But that's not the case, it's actually for an experiment. But, how and why have you brought them in? And what's it got to do with the particle model?

Other compounds are made from different combinations of atoms, like water… carbon dioxide… and table salt. See, in this salt solution there are water molecules and salt particles all mixed together. The particles in a liquid are constantly jiggling around, and the warmer the liquid is, the faster they’ll move.

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After we’ve removed all the water from the solution, there’s only salt left behind and this is pure water. And in one of those great moments in history where knowledge and opportunity coincide, scientists realised that a vast source of raw ingredients for these new plastics had already been discovered. Mrs Roberts: Yeah. So, a displacement reaction involves a metal and a compound of a different metal. In a displacement reaction a more reactive metal will displace, which means pushes out, a less reactive metal from its compound. Ben: OK, some filtration. Sure thing. So I'm going to pour this carefully. I'm just going to try and get the sand.

Salt is a substance that dissolves easily in water, to make a salt water solution. This is a mixture. We can separate the salt and the water from the salt water solution using distillation. A balanced equation gives more information about a chemical reaction because it includes the symbols and formulae of the substances involved. There are two steps in writing a balanced equation:Here we have two identical hot cups of tea. And we want to see how much sugar can be held in solution in these hot cups of tea. When no more sugar can dissolve, the solution is said to be saturated. VOICEOVER: Zach has a bowl of ice cubes with a mass of five hundred grams. After some time the ice cubes melt, but the scales still show five hundred grams. This is because melting the ice has not created or destroyed any atoms and the mass has stayed the same. This is known as the law of conservation of mass. It applies to both chemical reactions and physical changes. At room temperature, the water contains a certain amount of dissolved gases from the air. The water straight from the tap creates cloudy ice cubes because these gases that were dissolved in the water form tiny bubbles in the ice. The solubility of a solute in a solvent changes with temperature. And importantly, it depends on whether the solute is a gas or a solid. So, let's look at solids first.