SENSATIONAL SCIENCE 1: Custard Gone Crazy What you’ll need: • Custard powder (NB not instant custard) / cornflour • Water • Bowl • Spoon • Eggcup / spoon What to do: • Mix 8 eggcups of custard powder or cornflour with 4 eggcups of water, making sure to stir in the water slowly so you don’t get any lumps. (Don’t cook it!) The result is a strange yellow substance that will either act like a solid - if you punch it quickly, or roll it into a ball OR will act like liquid, if you touch it gently. If you increase the amounts of custard and powder, you could in theory fill a bathtub with the mixture, and run across the top without falling in. (You’d have to be very quick though!) What's happening? The custard powder and water mixture is a mixture of solid particles suspended in a liquid, called a "colloid". When you stir the mix slowly, the custard powder particles can move around in the water quite freely, and so it acts as a liquid. When you stir the mix faster or hold it in your hand tightly, the solid particles rub against each other causing friction. This makes them stick together and act like a solid. 2: Slime City What you’ll need: • Borax approx 4% solution (you can buy this in the local chemist) • White Glue • Water • Food Colouring • Ziploc Bag • Plastic cups • Tablespoon What to do: • Take a cup of water and add it to 1 tablespoon of borax. • Mix 1/4 cup glue with 1/4 cup of water. • In the Ziploc bag add and 1/2 a cup of borax solution to 1/2 a cup of the glue solution. Add a few drops of food colouring. • Seal the bag and knead the mixture. Your slime is ready to go…! What's happening? The borax enables the glue (polyvinyl acetate) molecules to join together to form larger molecules called polymers. This makes a thickened, slimey gel. 3: Help! Help! Volcano! What you’ll need: • Vinegar • Baking powder • Washing up liquid • Food colouring • Small plastic bottle • Balloon • Plate/tray • Clay (optional) • Tablespoon What to do: • Put 1 tablespoon of baking powder in the plastic bottle. If you have time make a volcano shape with the clay around the bottle. • Add a small amount of washing up liquid, and a few drops of food colouring. • Make sure that the volcano is on the tray / plate. • Add vinegar and stand well back… Variation 1: Place a balloon over the end of the bottle and collect the gas – it is heavier than air. Variation 2: Put a bung in the bottle and watch it fly out. BEWARE – this experiment is great – but it does stink. Don’t use repeatedly!! What's happening? This experiment demonstrates a classic acid base reaction. Carbon dioxide is given off when the vinegar reacts with the baking powder. Go back