Ice Cream: Colloidal Chemistry

What is a summer without ice cream cones, or a slice of apple pie without a melting scoop of vanilla ice cream? Though it looks simple – cream, milk, sugar and eggs – ice cream has some interesting science keeping it together. Solutions, Emulsions and Colloids A solution is the …

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Acids and Alkalis: Making Gases

When an acid is mixed with a carbonate, a type of alkaline chemical, the two chemicals react and form the gas carbon dioxide. This can be quite dramatic! Making Gas Pour a small amount of vinegar into a glass, add bicarbonate of soda (sodium bicarbonate) and stir. The acid and …

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Green Coins or Shiny Ones? Oxidation of Copper

New pennies and two pence pieces are bright copper, but after a while, they turn dull. This is because the copper reacts with oxygen in the air to form copper oxide, which is black and makes coins less shiny. In a similar way, iron and steel form iron oxide on …

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Growing Crystals

To grow crystals, you need to start with a saturated solution – water that has as much, sugar, salt or whatever crystal ingredient dissolved in it as it possibly can. Gently and carefully warming the solution in a saucepan, in a bath of hot water or on a radiator and …

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Breaking Down Colours: What’s in Your Pen

Chemistry uses chromatography to separate mixtures of chemicals. The word chromatography comes from the Greek words for ‘colour’ and ‘to write’. Paper chromatography is a simple form of chromatography, and can separate out the mixtures of different pigments and dyes in black and coloured inks and in food colourings. Separating …

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Why Oil and Water Don’t Mix

Oil and water don’t mix – they are described as ‘immiscible’. Crude oil floats on the sea after a spill from a tanker. Motor oil shows up as a sheen on puddles in the road. Olive oil separates out in salad dressing. But why don’t they mix? What is Oil? …

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Soft and Hard Water: Making More Bubbles

Different parts of the country have soft or hard water. Hard water is water that has travelled through certain types of rock, including limestone, chalk and dolomite, and has forms (salts) of calcium and magnesium dissolved in it, such as calcium carbonate, calcium bicarbonate and calcium magnesium carbonate. Soft water …

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