KS3 Chemistry Study & Question Book (CGP KS3 Study Guides)

Product Information

Mrs Roberts: Yes. So if we were to categorise metals by their reactivity, the most reactive metal would naturally be at the top. So, if I'm going to test you now. So, if a copper is added to a solution of magnesium chloride no reaction occurs. What does that tell you about the reactivity between copper compared to magnesium? Plastics are polymers and that's Greek for many parts. So they're a bit like this chain of paperclips. They're individual components linked together. 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. I’ll put the salt solution in an evaporating basin, and use a heat source like a Bunsen burner to gently increase the temperature of the water.

Place a small spot of the coloured mixture you are investigating onto the pencil line and allow it to dry. Ben: OK, here we go. I'll take the lid off. OK, there we go. Take a look at that. Now it's not a clear solution, is it? So, would we define the sand as insoluble in water?

Engage children with digital learning

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. VOICEOVER: The particles that make up gases and liquids move randomly. This movement allows the action of diffusion to happen.

With the proliferation of the motorcar and expansion of industry and cities, enormous quantities of oil and gas were being pumped out of the ground and processed into fuel. After we’ve removed all the water from the solution, there’s only salt left behind and this is pure water. Katie: Wow. That's amazing. That's blown my mind, Miss Roberts. It really has. Here's a couple more examples to prove it too.

Want to save more time

Teacher: You need to shake it for about five minutes and, once you're ready, remove the small bag and put the ice cream into a bowl or cone. Add your toppings and it should look something like this. The particles are really whizzing about in the water, and they’re escaping into the air, or evaporating, faster than ever. Carefully lower your paper into the water, letting the glass rod balance on the rim of the beaker. Make sure the pencil line is above the surface of the water.

Miss Roberts: So, it may look like the mass has increased, because the ice takes up more room than the liquid water. But, the mass has in fact stayed the same. 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. For example, if you spray some deodorant in your bedroom. The particles move from an area of high concentration, the place where you sprayed it, to an area of lower concentration - your bedroom doorway. Then, through the rest of the house. The perfume particles have diffused. 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. After a couple of days, the solution I left on the windowsill has also evaporated. The energy from the sun has warmed the solution, speeding up evaporation. Like before, the water has turned into gas in the air and the salt has been left behind.

Teaching about the latest events?

Slowly but surely, it's going in. So remember, acetone's the stuff that you've actually got in nail varnish remover.