Chemistry revision bites

Short bursts of information for C1, which I found helpful so thought you might too. They are based on what I was struggling with, but if there is a particular C1 topic you want me to create a card in this set for, then just comment and I'll do one ASAP :)

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Advantages of ethanol

Ethanol does not affect performance of the car, it can save money and it is carbon neutral.

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Disadvantages of biofuel

Much more crops need to be grown, so prices rise, setting up the industry is expensive, deforestation may occur, lots of water is needed and nitrogen oxides from burning have a higher concentration than fossil fuels.

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Biofuel

Biofuel comes from the products of organisms, such as methane from decaying animals. Vegetable oil is also used - some biodiesel is made from waste cooking oil and rapeseed oil.

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Hydrogenation (1)

Vegetable oils are liquid at room temperature. They are unsaturated, have double bonds and a low melting point. This is because there are weak forces between the molecules due to big gaps. Hydrogen is added at 60 C over a nickel catalyst (which speeds up the reaction) and the melting/boiling point is increased.

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Hydrogenation (2)

Some of the double bonds are replaced with single bonds, and the forces between the moclecules are stronger because of smaller gaps. The oils have a higher melting point and are solid at room temperature. They have been hardened and are 'hydrogenated' oils.

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Advantages of hydrogen

Hydrogen releases lots of energy when burnt, and no harmful gases are produced, only water vapour.

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Advantages of biofuel

Biofuel tackles global warming by using CO2 from the air, it costs little to convert an engine for use, it makes little contribution to the greenhouse effect, it is carbon neutral and biofuels are renewable. It also provides jobs and reduces the use of fossil fuels, and biofuels are non-toxic and can be used in any diesel vehicle.

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Advantages of using limestone

Limestone is cheap and easy to extract. It is also attractive and abundant (there's lots of it).

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Disadvantages of using limestone

Limestone reacts with acid rain, it's soft and crumbles when heated.

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Advantages of concrete

Concrete is strong when squashed, it sets hard and can be reinforced with steel.

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The periodic table and reactivity

Group 1 are highly reactive because there is only 1 electron on their outer shells. Group O are unreactive because their outer shells are full.

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Advantages of steel

Steel is strong and can be melted and remoulded. It is cheap and durable, and quick to erect. It is recyclable, and one painted it is unreactive.

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Ionic compounds

These are between a metal and a non metal. An electron from the metal is given to the metal to form an ion.

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Covalent compounds

These are between 2 non-metals, who share electrons to form a molecule.

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Bioleaching

This is a way of extracting metals from their compounds. Bacteria feeds on the minerals on the compound, which is separated into the metal and the non-metal. This is energy efficient, but slow, and is used when the ore only has a low concentration of metal.

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Ores

An ore is something that contains enough metal for it to be economically viable to extract. They are mined and usually contain unreactive metals which can be purified after extraction.

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Alloys of aluminium

Aluminium and copper is heat resistant, strong, cheap and used in wires. Aluminium and zinc is strong, less corrosive, hardwearing and used in boats and planes.

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Alloys of iron

The six main alloys:

Stainless steel is hard, strong and corrosion resistant. Low alloy nickel steel is resistant to stretching. Low alloy tungsten steel works at high temperatures. High carbon steel is very strong. High alloy chromium steel is chemically stable. Low carbon steel can bend easily.

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Aluminium

Aluminium is light, strong, corrosion resistant and is a good conductor. It is used to make a wide range of products and is extracted by electrolysis. Recycling aluminium saves energy because there is no need for electrolysis.

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Reactivity series

Potassium - sodium - lithium - calcium - magnesium - aluminium - zinc - iron - titanium - lead - copper - silver - gold - platinum

 

Mnemonic (Remember Charlie and Gordon)

Please stop lifting Charlie's mouldy apple-coloured zebras in the language class so Gordon perishes!

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Iron

Iron is less reactive than carbon, which is used to displace iron from iron oxide in a blast furnace: oxygen is removed, leaving pure iron.

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Smelting

Oxygen, a metal ore and carbon are heated in a blast furnace. The oxygen is removed, leaving the pure metal.

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Alloys of copper

Copper and nickel alloy is strong, less corrosive and used for sea pipes. Copper and zinc alloy (brass) is strong, easily moulded, less corrosive and used for instruments, door knockers and other products. Copper and tin alloy (bronze) is strong, bendable, hardwearing and used to make outdoor statues.

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Advantages of recycling metals

Recycling metals provides jobs, saves energyreduces pollution and improves facilities. There is less pressure on the environment, it reduces use of natural resources and provides materials for industry.

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Titanium

Titanium is strong, resistant to corrosion and has a high melting point. It is ideal for aircrafts, nuclear reactors, racing bikes and hip replacements. It is usually displaced with carbon, sodium or magnesium. Recycling titanium saves energy.

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Copper

Copper is extracted by smelting or chemical reactions. It is used in wiring and plumbing because it is a good conductor and corrosion resistant. It can be purified by electrolysis, but this is expensive. Copper is finite and there is a limited supply of it.

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