C2-Chemical Resources


The Earth's Structure

  • The crust is a thin, outer layer of solid rock
  • The lithosphere includes the crust and upper part of the mantle and is made of tectonic plates. It is cold and rigid and is over 100km thick
  • The mantle is the solid section between the crust and core and is rigid. As you go deeper into the mantle the temperature increases and it can flow very slowly
  • The core is just over half of the Earth's radius and the inner core is solid whilst the outer core is liquid
  • Radioactive decay creates a lot of heat inside the earth which creates convection currents in the mantle which causes the plates to move

Tectonic Plates

  • Big, rocky pieces that float on the mantle about 2.5cm each year
  • P-Waves and S-Waves pass through the mantle, P-Waves pass through the core. S-Waves can only travel through solids
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Plate Tectonics

For years, fossils were found on opposite sides of the World and people thought it was due to land-bridges which had sunk and covered by water. Also the coastlines of continents fitted together like a jigsaw

  • In 1914 Alfred Wegener said that Africa and South Africa had previously been one continent and then split and then he said there were matching layers in rocks on different continents and similar earthworms living in both South America and South Africa.
  • Wegener's theory of continental drift supposed that 300 million years ago and there had been one supercontinent which he called Pangaea

His theory explained that things couldn't be explained by land-bridges and other scientists were hostile. Drifting wasn't convincing and Wegener claimed it was caused by tidal forces and rotation but geologists showed this was impossible.

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Volcanic Eruptions

  • Volcanoes occur when molten rock from the mantle emerges through the Earth's crust
  • The crust at the ocean floor is denser than the crust below the continents
  • When the two tectonic plates collide and a dense oceanic plate is forced underneath a less dense continental plate which is called subduction. The oceanic crust tends to be coller at the edges of a tectonic plate so the edges sink easily
  • Igneous rock is made when any sort of molten rock cools down and solidifies, this type depends on how quicky the magma cools and the composition of the magma
  • Some volcanoes produce magma that forms iron-rich basalt and the lava from the eruption is runny. But if the magma is silica-rich rhyolite the explosion is explosive
  • Geologists study volcanoes to try and find out if there are any signs that a volcano eruption might happen soon
  • Being able to spot these clues they can predict erruptions with alot more accuracy but volcanoes are very unpredictable. But even knowing this can save lives
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Three Different Types of Rock

Sedimentary Rock

  • The are formed by sediment laid down in lakes and seas and over millions of years the layers get buried under more layers and the weight squeezes out the water, fluids flowing through the pores deposit natural mineral cement. Limestone is an example of this and is mostly formed from seashells. It is mostly calcium carbonate and when it is heated it is thermally decomposed

Metamorphic Rocks

  • They are formed by the action of heat and pressure on sedimentary rocks and as long as they don't melt they are classed as metamorphic. Marble is another form of calcium carbonate and high temperatures break it down which makes it harder with a more even texture

Igneous Rocks

  • Igneous rocks are formed when magma cools and they contain varioyus different minerals in randomly arranged interlocking crystals which makes them VERY hard. Granite is an example of this
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Construction Materials

  • Aluminium and Iron are extracted from ores in rocks. Rocks are a mixture of minerals and from minerals there are ores where we get useful materials from.
  • Glass is made by melting limestone, sand and soda. Heating up limestone with sand and soda until it melts and then when the mixture cools it becomes glass.
  • Bricks are made from clay which is a mineral formed from weathered and decomposed rock which is soft and when it is dug u it makes it eay to mould into bricks. It can be hardened by firing at very high temperature which makes it ideal as a building material as it can withstand the weight of bricks on top of them
  • Limestone and clay are heated to make cement. Clay contains aluminium and silicates and powdered clay and limestone are roasted in a kiln to make cement which will be mixed with water. Cement can be mixed with sand to make concrete which is a very quick and cheap way of constructing building. Reinforced concrete is a composite material which is a combination of concrete and steel which gives it the hardness of concrete an flexibility and strength of steel
  • Quarrying uses up land and destroys habitats and transporting rock can cause pollution and noise. It causes alot of dust and alot of disused sites can be dangerous as people can drown in lakes and they can collapse
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Extracting Pure Copper


Electrolysis can split up the impure copper and the pure copper as the copper is immersed in electrolyte which conducts electricity. This is copper sulfate solution and contains Cu2+ ions. It acts like a pump as it pulls electrons off copper atoms at the anode causing them to go into the solution then offers electrons at the cathode to nearby Cu2+ ions to turn them back into copper atoms. The impurities are dropped at the anode as a sludge whilst pure copper atoms bond to the cathode. PURE COPPER IS DEPOSITED AT THE PURE CATHODE. COPPER DISSOLVED FROM THE IMPURE ANODE.

  • Reduction is the gain of electrons and Oxidation is the loss of electrons

Recycling Copper Saves Money and Resources

  • It is cheaper to recycle copper than it is to mine and extract new copper from it ore and it only uses 15% of the energy than it does to mine and extract the same amount
  • But it is hard to convince people it is worth the effort and even then you have to seperate the copper from the other metals which takes time and energy
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An alloy is a mixture of a metal and other elements, it can be a mixture of two or more different metals but a metal and a non-metal. They have properties that would be more useful and different than if they were by themselves

Steel is an alloy of iron and carbon, steel is harder than iron and stronger than iron. Iron will also rust but steel is less likely to rust. Alot is made fom steel, bridges, washing machines, cutlery etc

Brass, Bronze, Solder, Amalgram are also alloys. Brass is an alloy of copper and zinc, brass is harder than either of them and can be used to make musical instruments and fittings such a door handles. Bronze is an alloy of copper and tin and it is much harder and stronger than tin and is resistant to corrosion, it is used to make springs and bells. Solder is an alloy of lead and tin and doesn't have a melting point and solidifies when cooled. Amalgram is an alloy containing mercury and it is used in dentistry.

Smart alloys such as nitinol have shape memory, made of titanium and nickel. This means they go back to their original shape after being bent and twisted. These can be used in glasses frames

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Building Cars

Iron and Steel corrode more than aluminium. Iron corrodes very easily, rusting only happens when there is contact with water and oxygen. The chemical reaction that takes place is an oxidation reaction as the iron gains oxygen to form iron(III) oxide which we call rust.                                         Iron + Oxygen + Water -> hydrated iron (III) oxide. Rust flakes off and cars in coastal places rust much more quickly

Car Bodies

  • Aluminium has a lower density so the car will be lighter and have a better fuel economy. A car made of aluminium corrodes less but it does cost alot more than steel and iron which is why steel is often used instead. Used in the engine parts
  • Steel is strong
  • Glass is transparent so is used in the windows
  • Plastics are light and hardwearing so they are used for internal coverings
  • Fibres are hard-wearing and so are used in seating and flooring

Recycling cars is important and alot of metal from them is recycled. EU laws now say 85% of cars should be recycled. The biggest problem is sorting out all the different types of materials

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Acids and Bases

Acids from pH 1-4. pH 1 is car batteries and stomach acid, vinegar and lemon juice are pH 3 and acid rain is pH 4. Neutral is pH 5- 7. Normal rain is pH 5 and pure water pH 7. Alkalies are pH 8-14. Washing up liquid is pH 8, soap powder is pH 11 and drain cleaner pH 14.

An indicator changes colour depending on the pH of a substance which is very useful for estimating.

Acids and Bases neutralise eachother

  • An acid is a substance with a pH of less than 7, Acids H+ ions in water so the pH of an acid is determined by the concentration of the H+ ions
  • A base is a substance with a pH of greater than 7. An alkali is a base that is soluble in water. Alkalis form OH- ions in water
  • The reaction between acids and bases is called neutralisation: acid + base -> salt + water
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Reactions of Acids

Metal Oxides and Metal Hydroxides are Bases

  • Some metal Oxides and Metal Hydroxides dissolve in water and the soluble compounds are alkalis and even bases that won't dissolve in water will react with acids
  • Acid + Metal Oxide -> Salt + Water
  • Acid + Metal Hydroxide -> Salt + Water
  • Hydrochloric Acid + Copper Acid -> Copper Chloride + Water

Acids and Carbonates produce Carbon Dioxide

  • Acid + Carbonate -> Salt + Water + Carbon Dioxide
  • Hydrochloric Acid + Sodium Carbonate -> Sodium Chloride + Water + Carbon Dioxide

Acids and Ammonia produce Ammonium Salts

  • Acid + Ammonia -> Ammonium Salts
  • Hydrochloric acid + ammonia -> ammonium chloride
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The three main essential elements in fertilisers are phosphorus, nitrogen and potassium. These elements are missing from the soil if they have been used up by a previous crop. Fertilisers replace these elements or provide more of them which increases the crop yield. The fertiliser must first dissolve in water

The population of the World is increasing rapidly and fertilisers increase the crop yield so the more fertiliser we make, the more people we can feed. If we use too many fertilisers we risk polluting our water supplies and causing eutrophication

When fertiliser is put on fields some of it inevitably runs off and goes into rivers and streams. The level of nitrates and phosphates in the water increases. Algae living in the water use the nutrients to multiply rapidly creating an algae boom which blocks off the light to the river plants below and they die. Aerobic bacteria feed on dead plants and start to multiply and they use up the oxygen in the water so anything dies. This process is called eutrophication

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Preparing Fertilisers

You can make most fertilisers through the titration method as you can pick an acid and alkali to get the salt that you want. However, you need ammonia and nitric acid to get ammonium nitrate which is a fertiliser.

Percentage Yield

  • The mass of a product that you end up with is called the YIELD of a reaction
  • In practice you never get 100% yield as not all the reactant will be converted into a product which will mean the product is slightly less than you would expect. The more reactants you start with the higher the actual yield.
  • Percentage yield is always somewhere between 0 and 100%
  • 100% yield means that you got all the product you expected to get
  • 0% yield means that no reactants were converted into product
  • Predicted Yield of a reaction is just the amount of product that you'd get if all the reactant was converted into product
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The Haber Process

The Haber Process is a reversible reaction: the nitrogen is obtained easily from the air which is 78% nitrogen and 21% oxygen. The hydrogen comes from the cracking of oil fractions or natural gas. Because the reaction is reversible not all the nitrogen and hydrogen will convert ammonia. The N2 and H2 which don't react are recycled and passed through again so none is wasted.

Pressure: High (200 atmospheres), Temperature: 450'c, Catalyst: Iron

  • High temp favours the forwards reaction so the pressure is set at 200 which increases percentage yield
  • High temps favour the reverse reaction so high temp decreases the percentage yield of ammonia
  • Lower temps mean slow reaction rates so they use high temps anyway
  • 450'c is the optimum temperature as it gives a fast reaction rate and a reasonable percentage yield
  • The unused hydrogen and nitrogen is recycled so nothing is wasted
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Minimising the Cost of Production

  • Industry needs to keep its energy bills as low as possible so if a reaction needs high temperature the running costs will be higher
  • This is kept to a minimum by recyling any materials that haven't reacted, a good example of this in the Haber Process. The % yield of the reaction is quite low but the unreacted N2 and H2 can be recycled
  • Everyone has to be paid and labour-intensive processes can be expensive. Automation cuts running costs by reducting the people involved but companies have to consider whether they want to save money on wage bill or machinery cost
  • The cost of equipment depends on the conditions it has to cope with so it costs far more to make something to withstand very high pressures than something that only needs to work at atmospheric pressures
  • The faster the reaction goes the better it is in reducing the time and costs of production so the rates of reaction are increased by using a catalyst. The increase in production rate has to balance the cost of a catalyst in the first place and replacing any that gets lost
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Salt is mined from underneath Chesire which was left millions of years ago when ancient seas evaporated. Rock salt is a mixture of salt and impurities so it is drilled, blasted and dug out. But it can also be mined by pumping hot water underground the salt dissolves and the salt solution is forced to the surface by the pressure of the water and this is called solution mining. When mining is finished you have to fill the holes which we call subsidence.

Electrolysis of Brine gives hydrogen, chlorine and NaOH. Concentrated brine is electrolysed industrially, the electrodes are made of an inert material so they won't react with the electrolyte and the products. There are three useful products: hydrogen gas is given off at the -ve cathode; chlorine gas is given off at +anode; sodium hydroxde NaOH is formed from the ions left in the solution

The electrolysis of brine is done by the Chlor-alkali Industry, the products of the chlor-alalie process are used for all kinds of things. Hydrogen is used to mak ammonia and margarine, chlorine is used to disinfect water and to make plastics, hydrochloric acid and solvent an sodium hydroxide is used to make soap or househld bleach.

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