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List of Chemicals
Some properties of the chemicals used or discussed during the teaching of Common Entrance science
| Name | Appearance | Element Compound Mixture |
Some useful information |
| Acetic
acid (ethanoic acid) |
Colourless liquid | Compound | Acetic acid is the acid found in vinegar. |
| Acetone (propanone) | |||
| Colourless liquid | Compound | A useful solvent. | |
| Air | Colourless gas | Mixture | A
mixture of gases. Approximate
composition:
Nitrogen......... 78% |
| Aluminium | Grey metal | Element (M) | A light, brittle metal. Used to make kitchen foil and low density alloys. |
| Ammonia solution | Colourless liquid | Mixture | An alkaline liquid with a very strong, pungent smell. Often used as a household cleaner. |
| Anhydrous copper sulphate | White powder | Compound | Made
by heating hydrated copper sulphate.
If water is added it turns blue and gets warm. It is often used as a test for water. |
| Anhydrous cobalt chloride | Blue powder | Compound | Made
by heating hydrated cobalt chloride.
If water is added it turns pink. It is often used as a test for water. |
| Argon | Colourless gas | Element (N) | An inert gas. Often put in light bulbs to prevent the filament oxidising. It is present in the atmosphere (just under 1%). |
| Calcium oxide | White solid | Compound | Often
called lime, it reacts with water to form an alkaline solution and is put
on the ground by farmers to neutralise an acid soil.
Used industrially in the manufacture of cement. |
| Calcium carbonate | White solid | Compound | It is the compound present in marble, limestone, chalk and bones. It reacts with acids to form carbon dioxide gas. When heated it decomposes to form carbon dioxide gas and leave calcium oxide (a white solid). |
| Calcium hydroxide | White solid | Compound | Dissolves in water to form LIMEWATER, an alkaline liquid used as a test for carbon dioxide. |
| Calcium | Grey metal | Element (M) | Burns with a bright red flame to form calcium oxide, a white alkaline solid. It reacts with water to form hydrogen gas. |
| Carbon | Black solid | Element (N) | The element carbon is present in all living things. It burns in air to form carbon dioxide. It exists naturally as graphite and diamond. In certain forms it will conduct electricity. |
| Carbon dioxide | Colourless gas | Compound | A dense gas (heavier than air). Does not support combustion. It is the gas produced during respiration in living organisms and used by plants during photosynthesis. It is present in the atmosphere (about 0.03%) and causes rainwater to be slightly acidic. The test for carbon dioxide is to bubble it through limewater which will go milky. Used in fire extinguishers and fizzy drinks. |
| Citric acid | White crystals | Compound | Citric acid is the compound which gives lemons and other citrus fruits their sharp taste. |
| Cobalt
chloride (hydrated) |
Pink crystals | Compound | If heated it will decompose to form anhydrous cobalt chloride (blue) and give off water vapour. |
| Copper
sulphate (hydrated) |
Blue crystalline solid | Compound | If heated it will decompose to form anhydrous copper sulphate (white) and give off water vapour. |
| Copper oxide | Black powder | Compound | Reacts with dilute sulphuric acid to form a blue solution of copper sulphate. |
| Copper carbonate | Green powder | Compound | If heated it will decompose to form copper oxide (a black powder) and evolve carbon dioxide gas. |
| Copper | Pink metal | Element (M) | If heated it forms a black layer of copper oxide on the surface. Used to make electric wires and water pipes. |
| Ethanol (alcohol) | Colourless liquid | Compound | Flammable liquid produced by the fermentation of sugars (using yeast). Often used as a solvent. Alcohol burns to form carbon dioxide and water. |
| Gold | Yellow metal | Element (M) | Very dense unreactive metal. Will not tarnish. Used in jewellery. Often used to coat electrical contacts eg in switches. |
| Graphite | Black solid | Element (N) | Graphite is a form of carbon. It is the black substance used to make pencil leads. Graphite will conduct electricity. |
| Hydrochloric acid (dilute) | Colourless liquid | Mixture | Used in the laboratory prep. of carbon dioxide by reacting it with marble chips. |
| Hydrogen | Colourless, flammable gas | Element (N) | The
least dense (lightest) of all substances.
The test for hydrogen is to see if it burns with a squeaky pop. It burns to form water. |
| Iodine | Grey solid | Element (N) | Sublimes into a purple vapour when heated. Iodine is an important test for STARCH. If a drop of iodine solution is placed onto some starch a blue/black colour is formed. |
| Iron | Grey metal | Element (M) | It is the only common metal attracted to a magnet. It reacts slowly with acids and goes rusty when exposed to a mixture of air and water. (Rust is hydrated iron oxide). |
| Iron oxide | Brown powder | Compound | It
is the compound found in iron ore from which iron can be obtained by
reduction with carbon.
It can be coated over thin plastic to make up recording tape or floppy disks. |
| Lead | Grey metal | Element (M) | Soft grey, heavy metal. It is not very reactive and is sometimes used as a roof covering. |
| Limewater | Colourless liquid | Mixture | An alkaline liquid that turns milky when carbon dioxide gas is bubbled through it. (used as a test for carbon dioxide). |
| Litmus indicator | Purple liquid when neutral. Can also be red or blue. | Mixture | Used
as a test for acids or alkalis.
Red litmus turns blue when added to an acid. Blue litmus turns red when added to an alkali. |
| Magnesium oxide | White solid | Compound | Dissolves in water to form magnesium hydroxide, a weak alkali. |
| Magnesium hydroxide | White solid | Compound | A mild alkali used to make 'Milk of magnesia', a medicine used to help acid indigestion. |
| Magnesium | Grey metal | Element (M) | It burns with an intense white flame to form magnesium oxide, a white solid that dissolves in water to form an alkaline solution. |
| Mercury | Grey liquid metal | Element (M) | The
only liquid metal. Very dense (heavy).
Sometimes used in tilt switches. |
| Nitrogen | Colourless gas | Element (N) | The most abundant gas in the atmosphere. It is not very reactive. Important as a plant food and so is often used in fertilizers. Makes up about 78% of the atmosphere. |
| Oxygen | Colourless gas | Element (N) | Oxygen is needed by living organisms for respiration. It is produced by plants during photosynthesis. It supports combustion. It makes up about 21% of the atmosphere. The test for oxygen is see if it relights a glowing splint. Main industrial use is in the steel industry. also used for welding, in hospitals and in rocket fuels. Prepared in the lab. by heating potassium permanganate and in industry by the fractional distillation of liquid air. |
| Petrol | Pale yellow liquid | Mixture of compounds | Petrol is a HYDROCARBON. Like all hydrocarbons it will burn to form carbon dioxide and water. |
| Potassium permanganate | Dark purple crystals | Compound | When heated it DECOMPOSES to form oxygen gas. |
| Sodium | Grey metal | Element (M) | Soft grey metal. Very reactive. Reacts violently with water to form am alkaline solution. Dangerously reactive with acids. |
| Sodium carbonate | White solid | Compound | Dissolves
easily to form an alkaline solution.
It is used to make WASHING SODA. |
| Sodium hydroxide | White solid | Compound | Dissolves readily in water to form a strong alkali. Very caustic - must be handled with graet care. |
| Sulphur | Yellow solid | Element (N) | If heated it first MELTS into an orange liquid and then BURNS to form a pungent smelling acidic gas called sulphur dioxide. |
| Sulphur dioxide | Acidic gas with a pungent smell. | Compound | Dissolves easily in water to form an acidic solution. It is the gas responsible for acid rain and is often formed when fossil fuels are burnt. |
| Sulphuric acid (dilute) | Colourless liquid | Mixture | Often used to produce hydrogen gas by reacting it with granulated zinc. |
| Universal indicator | Green liquid | Mixture | Universal indicator is used to test the pH value of a solution. See separate table. |
| Water | Colourless, neutral liquid | Compound | Water
is a compound of hydrogen and oxygen.
It is formed when either hydrogen gas or any hydrocarbon (eg wax, petrol, natural gas) is burnt. It has a boiling point of 100oC and freezes at 0oC. Water is a good solvent. It is a vital component in all living things. |
| Wax | Translucent solid | Mixture of compounds | Wax is a HYDROCARBON. Like all hydrocarbons it will burn to form carbon dioxide and water. The flame from a burning candle looks yellow due to small, very hot specks of soot (carbon). Being a mixture it does not have a definite melting point. |
| Zinc oxide | White powder | Compound | It turns yellow when hot but white again when cold. |
| Zinc | Grey metal | Element (M) | Used
in the laboratory preparation of hydrogen gas by reacting it with dilute
sulphuric acid.
Sometimes plated over iron to stop the iron rusting (called galvanized iron) |
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