What is the crust like?
Thin and rocky.
What does the core contain?
Iron.
What is the first part of the Earth's structure?
The crust.
What is the second part of the Earth's structure?
The mantle.
What is the third part of the Earth's structure?
The outer core.
What is the fourth part of the Earth's structure?
The inner core.
Why is it difficult to collect information about the Earth?
Mines and drills are only a few kilometres into the crust.
What do scientists use to study the structure of the Earth?
Seismic waves, caused by earthquakes.
What is the Earth's lithosphere?
A relatively cold, rigid outer part of the Earth made of the crust and top parts of the mantle.
What are tectonic plates?
Cracked, large interlocking pieces that are found at the top of the lithosphere.
What are oceanic plates?
Plates that sit under the ocean.
What are continental plates?
Plates that form the continents.
Why do the tectonic plates sit on top of the mantle?
They are less dense.
How far does a tectonic move per year?
Around 2.5cm.
What does the movements of tectonic plates cause?
Earthquakes and volcanoes at the boundaries between the plates.
What are the properties of the mantle?
Just below the crust, it is relatively cold and rigid. At greater depths, it is hot and is a fluid, which allows it to flow.
How are convection currents formed in the mantle?
By heat released from radioactive decay in the core.
What do convection currents in the mantle cause?
They cause magma to rise to the surface at the boundaries of the plates.
What happens when molten rock solidifies?
Igneous rock is formed.
What does the slow movement of magma cause?
It causes the tectonic plates to move.
What type of tectonic plate has a higher density?
The oceanic crust.
What type of tectonic plate has a lower density?
The continental crust.
What happens when an oceanic plate collides with a continental plate?
The oceanic plate slides under the continental plate.
What is it called when an oceanic plate slides under a continental plate?
Subduction.
What happens to the oceanic plate as it slides under a continental plate?
It is partially re-melted.
What is formed when plates move apart?
Rift valleys.
What are mountain ranges formed by?
Sedimentary rock being forced upwards due to subduction.
What was Alfred Wegener's theory?
The surface of the Earth was changing, based around the idea that millions of years ago, all the continents were joined together.
What did Wegener notice about the pieces of continent around the Earth?
They all fit together like a jigsaw.
What did Wegener notice about the geology of Scotland and Canada?
They were very similar.
What did Wegener notice about the geology of Africa and South America?
They were very similar
What did Wegener notice about animal and plant fossils
Similar fossils of plants and animals were found on two different continents, such as Africa and South America.
What did Wegener notice about the rock formations in South America and Africa?
There were matching formations and mountain chains.
What did the studies in the 1960s show about plate tectonics?
That the plates are moving apart and the age of rock increases as you move away from the boundary.
What was Wegener's theory called?
The continental drift.
Where do volcanoes form?
They form at places where magma can find its way through weaknesses in the Earth's crust.
Why does magma rise through the crust?
It has a lower density than the crust.
Why do geologists study volcanoes?
It helps them understand the structure of the Earth.
What do geologists attempt to predict in volcanoes?
They try to predict when a volcano will erupt to give an early warning.
Why is it dangerous to live near a volcano?
Predictions of the eruptions can't be predicted with accuracy.
Why might it be a good idea to live near a volcano?
The volcanic soil is very fertile, which is good for growing crops and plants.
Why is thick lava more dangerous than runny lava?
It erupts more violently and catastrophically.
What happens when liquid rock cools?
It forms igneous rock.
What does igneous rock consist of?
Very hard and interlocking crystals of different sizes.
In igneous rock, how are large crystals formed?
They are formed when the rock cools slowly.
In igneous rock, how are small crystals formed?
They are formed when the rock cools quickly.
Why is iron-rich basalt lava safer than silica-rich rhyolite lave?
It is quite runny and has much safer eruptions.
What can rhyolite (thick) lava produce?
Pumice, volcanic ash and bombs.
What is a tsunami?
A huge wave caused by volcanic or earthquake activity.
How is a tsunami formed?
When energy from an earthquake vertically jolts the seabed by several metres.
Where is iron and aluminium extracted from?
Rocks called ores.
How is a brick made?
Baking clay that has been extracted from the Earth.
What can be made from sand?
Glass, concrete and cement.
How would limestone, granite, marble and aggregates be extracted?
They would be extracted from the Earth.
What needs to happen to material rocks to form building materials?
They have to be shaped.
Why is limestone the easiest to shape?
It is the softest.
What material rock is the hardest to shape?
Granite.
Why do rocks differ in hardness?
The ways they were formed.
What type of rock is limestone?
Sedimentary.
What type of rock is marble?
Metamorphic.
How is marble formed?
When limestone that has been put under pressure is heated, which makes it harder.
What type of rock is granite?
Igneous.
What is a sedimentary rock?
A rock that has been formed by sediments that has settled in an area of water and has been compressed.
What creates the sediments for sedimentary rock?
The sediments come from eroded rocks (carried by rivers or ice) and from the skeletons of sea creatures.
What is a metamorphic rock?
A rock that has been put under tremendous heat and pressure, causing them to change into another type of rock.
What properties do metamorphic rocks have?
They are usually resistant to weathering and erosion.
What is an igneous rock?
A rock formed by magma from the molten interior of the Earth.
How is igneous rock formed?
When magma erupts and cools.
What are limestone and marble rocks mainly made from?
Calcium carbonate.
What is the symbol equation for calcium carbonate?
CaCO3
What happens when calcium carbonate is heated?
It breaks down into calcium oxide and carbon dioxide.
What is the name of the reaction when one material breaks down into two or more new substances when heated?
Thermal decomposition.
How is cement formed?
By heating clay and limestone together.
How is concrete formed?
When cement is mixed with sand, aggregates and water, being allowed to set.
Why is normal concrete not that useful?
It is very hard, but isn't strong.
How can concrete be strengthened?
By allowing it to set around steel rods to reinforce it.
What is reinforced concrete?
A composite material.
What is a composite material?
It combines the best properties of each component material.
What does reinforced concrete combine?
The strength and flexibility of the steel bars with the hardness of the concrete.
How is rock extracted from the Earth?
From mines and quarries.
What are the disadvantages of quarries?
They are noisy, dusty, taking up land and changing the shape of the landscape. They also increase the local road traffic.
What are the advantages of quarries?
They create jobs and they supply the heavy demand for the products of quarrying. They provide income to local councils through taxation and it is an important part of the UK economy.
Due to quarrying, what can heavy traffic cause?
Pollution and congestion
What is taken away due to quarrying?
Wildlife habitats and valuable agricultural land.
How can copper be extracted from copper ore?
By heating it with carbon.
What is the disadvantage of extracting copper from copper ore by heating it with carbon?
It uses a lot of energy which means it is expensive.
What is the process of reduction in copper oxide?
When the oxygen is removed from the copper oxide.
What is one of the main advantages of recycling copper?
It is cheaper than extracting it from ore.
What can recycling copper conserve?
It helps conserve the world's limited supply of copper ore, whilst using less energy.
Why can it difficult to recycle copper?
The copper could have other metals stuck to it.
How can impure copper be purified?
By the process of electrolysis.
What does electrolysis use?
An electric current to break down compounds into simpler substances.
What happens in electrolysis of copper?
Electricity is passed through a solution called an electrolyte - copper sulfate solution - to make simpler substances.
What are electrodes used for?
They allow the electricity in electrolysis to flow through the electrolyte.
What is an anode made from?
Impure copper.
What is a cathode made from?
Pure copper.
What charge is an anode?
Negative.
What charge is a cathode?
Positive.
What process occurs at an anode?
Oxidation, as electrons are lost.
What process occurs at a cathode?
Reduction, as electrons are gained.
Why does the impure copper anode loses mass in electrolysis of copper?
The copper oxidises in the copper sulfate solution.
Why does the pure copper cathode gain mass?
The copper is deposited.
What is an alloy?
A mixture of a metal with another element.
What are bronze and steel metals?
Alloys.
What does an alloy do?
They improve the properties of a metal to make them more useful.
What is amalgam used for?
Fillings in teeth. It is made from mercury.
What is solder used for?
To join wires. It is made from lead and tin.
What is brass used for?
To create door handles, coins and musical instruments. It is made from copper and zinc.
What is a smart alloy?
An alloy that can be bent and twisted.
Why is nitinol a smart alloy?
It returns to its original shape when it is heated. It has shape memory.
What is nitinol used for?
Frames of reading glasses.
What is the role of nylon fibre in a car?
It is used to make the seatbelts, as it is strong and flexible.
What is the role of glass in a car?
It is used to make the windows as it is transparent.
What is the role of plastic in a car?
It is used for the trim as it is rigid and doesn't corrode.
What is the role of steel in a car?
It is used to make the body as it is strong and malleable.
What does malleable mean?
It is able to be pressed into shape without breaking or cracking.
What is the role of aluminium in a car?
It is used to make the alloy wheels as it is lightweight and doesn't corrode in moist conditions.
What are the properties of aluminium?
It resists corrosion, it is malleable and conducts electricity.
What are the properties of iron?
It is dense, magnetic, malleable and conducts electricity.
What is steel an alloy of?
Iron and carbon.
Why is steel used to make cars?
It is harder and stronger than iron, and doesn't corrode as fast.
Why is aluminium used to make car bodies?
It is lighter than steel, corrodes less but is a lot more expensive.
How will a car benefit from having an aluminium body?
It will have a longer lifetime as the aluminium doesn't corrode.
How does aluminium benefit a car's fuel economy?
As it is less dense than steel, the car will be lighter which results in a better fuel economy.
What is rusting an example of?
An oxidation reaction.
What does rusting need to occur?
Iron, water and oxygen.
What increases the speed of rust?
When the water is salty or is acid rain.
Why doesn't aluminium react and corrode in air and water?
It quickly forms a protective layer of aluminium oxide.
What does a layer of aluminium oxide do?
It stops any air or water from coming into contact with the metal. It will not flake off.
What is added to iron in the presence of water?
Oxygen.
What is the problem of separating in recycling?
It is tricky and time-consuming.
What does recycling save?
It saves natural resources and avoids disposal problems.
What does recycling allow?
It allows less quarrying, less energy is used to extract new materials from ores, limited ore reserves will last longer and disposal problems are reduced.
What does recycling plastics and fibres reduce?
The amount of crude oil needed to make them, conserving oil reserves.
What does recycling always do?
Protects the environment.
What is the symbol for ammonia?
NH3
What type of gas is ammonia?
Alkaline.
What is ammonia made from?
Nitrogen and hydrogen.
What can ammonia be used to make?
Nitric acid and fertilisers.
Why are cheap fertilisers needed?
They help produce enough food for the growing world population.
What type of reaction makes ammonia?
A reversible reaction.
What happens when ammonia decomposes?
It forms hydrogen and nitrogen.
What is the process called where ammonia is made?
The Haber process.
What is the word equation for ammonia?
Nitrogen + hydrogen ---> ammonia
What is the symbol equation for ammonia?
N2 + 3H2 ---> 2NH3
Why aren't optimum conditions used to make ammonia?
It is too expensive to maintain.
Instead of optimum conditions, what is the compromise made to the pressure when making ammonia?
The nitrogen and hydrogen mixture is under the high pressure of 200 atmospheres.
Instead of optimum conditions, what is the compromise made to the temperature when making ammonia?
The nitrogen and hydrogen mixture is passed over an iron catalyst at 450�C.
As a percentage, how much of the reactant gases make ammonia?
15%
What happens to the unreacted gas when producing ammonia?
It is recycled.
After passing over the iron catalyst, what happens to the ammonia?
It is cooled, condensed and then pumped off as a liquid.
What does the cost of making a new substance depend on?
The price of energy, the labour costs, how quickly the substance can be made, the cost of starting materials and the cost of the equipment needed.
How does pressure affect the cost of making a new substance?
The higher it is, the higher plant cost.
How does temperature affect the cost of making a new substance?
The higher the temperature, the higher the energy cost.
How do the catalysts affect the cost of making a new substance?
They are expensive, but production costs are reduced because they increase the rate of reaction.
How does the number of people affect the cost of making a new substance?
The higher the amount of workers, the more people need paying. Automation reduces the wage bill.
How does the amount of unreacted materials affect the cost of making a new substance?
They are recyclable, which reduces costs.
What needs to be interpreted in reversible reactions?
Data percentage yield.
How do you calculate percentage yield?
actual yield / predicted yield x 100
What is the actual yield?
The mass of product made when the reaction is carried out for real.
What do economic considerations determine?
The conditions used in the manufacture of materials.
How does percentage yield fall under economic considerations?
It must be high enough to produce enough daily yield of product.
How can a low percentage yield be accepted?
Providing the reaction can be repeated many times with recycled starting materials.
How does the rate of reaction fall under economic considerations?
It must be high enough to produce enough daily yield of product.
Why should optimum conditions be used?
It gives the most economical reaction, but could mean a slower reaction or a lower percentage yield at a lower cost.
What is important about the production of ammonia?
The maximum amount is made in the shortest possible time at a reasonable cost, which requires a compromise.
For the Haber process, what does a low temperature do?
It increases the yield but the reaction is too slow.
For the Haber process, what does a high pressure do?
It increases the yield but becomes more expensive as the yield increases.
For the Haber process, what does a catalyst do?
It increase the rate of the reaction but doesn't change the percentage yield.
In full, how is the compromises met in the Haber process?
A temperature of 450�C, pressure of 200 atmospheres and a catalyst made of iron.
Why is the compromise met in the Haber process?
It gives a fast reaction with an acceptable percentage yield.
What are indicators?
Chemicals that change colour to show changes in pH.
How many colours does litmus have?
2.
On the pH scale, what are acids?
Substances with a pH of less than 7.
On the pH scale, what are bases?
The oxides and hydroxides of metals, with a pH of greater than 7.
What colour does acid change an indicator to?
Yellow to red.
What colour do bases turn an indicator to?
Blue to purple.
What are soluble bases?
Chemicals with a pH greater than 7 that can dissolve in water - they are called alkalis.
How can you find the pH of a solution?
Using universal indicator.
What happens when an acid is added to an alkali?
The pH of the solution decreases as the acid neutralises the alkali to reach pH 7.
What happens when an alkali is added to an acid?
The pH of the solution increases because the alkali neutralises the acid to reach pH 7.
How can acids be neutralised, other than using alkalis?
Using carbonates.
What is produced when an acid is neutralised by using carbonates?
A salt, water and carbon dioxide.
What is the word equation for the neutralisation of acid by carbonates?
Acid + carbonate ---> salt + water + carbon dioxide
Where does the first name of a salt come from?
The name of the base or carbonate used.
What will sodium hydroxide make?
Sodium salt.
What will copper oxide make?
Copper salt.
What will calcium carbonate make?
Calcium salt.
What will ammonia make?
Ammonium salt.
Where does the second name of a salt come from?
The acid used.
What will hydrochloric acid produce?
Chloride salt.
What will sulfuric acid produce?
Sulfate salt.
What will nitric acid produce?
Nitrate salt.
What will phosphoric acid produce?
Phosphate salt.
What happens when potassium hydroxide is neutralised with nitric acid?
Potassium nitrate is produced.
What do alkalis in solution contain?
Hydroxide ions.
What do acids in solution contain?
Hydrogen ions.
How can neutralisation be described?
By using the ionic equation.
What is the ionic equation?
H+ + OH- ---> H2O
What is the symbol equation for adding hydrochloric acid to sodium hydroxide?
NaOH + HCl ---> NaCl + H2O
What is the symbol equation for adding hydrochloric acid to potassium hydroxide?
KOH + HCl ---> KCl + H2O
What is the symbol equation for adding hydrochloric acid to copper oxide?
CuO + 2HCl ---> CuCl2 + H20
What is the symbol equation for adding hydrochloric acid to ammonia?
NH3 + HCl --->NH4Cl
What is the symbol equation for adding sulfuric acid to sodium hydroxide?
2NaOH + H2SO4 ---> Na2SO4 + 2H2O
What is the symbol equation for adding sulfuric acid to potassium hydroxide?
2KOH + H2SO4 ---> K2SO4 + 2H2O
What is the symbol equation for adding sulfuric acid to copper oxide?
CuO + H2SO4 ---> CuSO4 +H2O
What is the symbol equation for adding sulfuric acid to ammonia?
2NH3 + H2SO4 ---> (NH4)2SO4
What is the symbol equation for adding nitric acid to sodium hydroxide?
NaOH + HNO3 ---> NaNO3 + H2O
What is the symbol equation for adding nitric acid to potassium hydroxide?
KOH + HNO3 ---> KNO3 + H2O
What is the symbol equation for adding nitric acid to copper oxide?
CuO + 2HNO3 ---> Cu(NO3)2 + H2O
What is the symbol equation for adding nitric acid to ammonia?
NH3 + HNO3 ---> NH4NO3
What is the symbol equation for adding hydrochloric acid to sodium carbonate?
Na2Co3 + 2HCl ---> 2NaCl + H2O +CO2
What is the symbol equation for adding hydrochloric acid to calcium carbonate?
CaCO3 + 2HCl ---> CaCl2 + H2O + CO2
What is the symbol equation for adding sulfuric acid to sodium carbonate?
Na2CO3 + H2SO4 ---> Na2So4 + H2O + CO2
What is the symbol equation for adding sulfuric acid to calcium carbonate?
CaCO3 + H2SO4 --->CaSO4 + H2O + CO2
What is the symbol equation for adding nitric acid to sodium carbonate?
Na2CO3 + 2HNO3 ---> Ca(NO3)2 + H2O + CO2
What are fertilisers?
Chemicals that give plants essential chemical elements needed for growth.
What do fertilisers do?
Make crops grow faster and bigger.
How are animals impacted by fertilisers?
They are killed in waterways, which is known as eutrophication.
What is eutrophication?
The overuse of fertilisers, which changes the ecosystem in lakes, rivers and streams.
What are the three main elements found in fertilisers?
Nitrogen, phosphorus and potassium. Urea can also be used as a fertiliser.
Why must fertilisers be soluble in water?
So that they can be taken in by the roots of plants in a solution.
How do fertilisers increase crop yield?
They replace essential elements in the soil that have been used up by a previous crop and they provide nitrogen as soluble nitrates which are used by the plant to make proteins.
How can some fertilisers be formed?
By neutralising an acid with an alkali.
How is ammonium sulfate made?
By neutralising sulfuric acid with ammonia.
How is ammonium nitrate made?
By neutralising nitric acid with ammonia.
How is ammonium phosphate made?
By neutralising phosphoric acid with ammonia.
How is potassium nitrate made?
By neutralising nitric acid with potassium hydroxide.
What apparatus is used to make a fertiliser by neutralisation?
A burette, measuring cylinder and filter funnel.
What is the first step to making a fertiliser?
By measuring out the alkali into a beaker using a measuring cylinder.
What is the second step to making a fertiliser?
By adding acid from a burette and using a glass rod to put a drop of solution onto indicator paper. Add the acid a bit at a time.
What is third step to making a fertiliser?
Transfer the solution to an evaporating dish, and evaporate the solution slowly until crystals form on the end of a cold glass rod. Leave to cool and crystallise.
What happens when fertilisers used by farmers are washed into a lake or river?
The levels of nitrates and phosphates are increased in the water and simple algae grows.
What does an algal bloom do?
It blocks sunlight to other plants, causing them to die and rot.
What does aerobic bacteria do?
It feeds on dead organisms and increases in number.
What happens to oxygen during the process of eutrophication?
Aerobic bacteria use it up until is all nearly gone. There isn't enough oxygen to support larger organisms, leaving fish and other aquatic animals to suffocate.
What is sodium chloride used for?
As a food preservative and flavouring (table salt).
What is sodium chloride an important source of?
Chlorine and sodium hydroxide.
How can sodium chloride be found?
From being removed from the sea or mined from salt deposits.
How is sodium chloride mined?
In Cheshire as a solid rock salt. This has led to subsidence in the area. Also, it can be mined by solution mining for the chemical industry.
Why must the electrodes in electrolysis of sodium chloride solution be made from inert materials?
The products are very reactive.
What does inert mean?
Inactive.
What does the process of electrolysis of sodium chloride produce?
Sodium hydroxide in the solution, hydrogen at the cathode and chlorine at the anode.
How can you test for chlorine?
Using litmus paper.
What happens to litmus paper if chlorine is present?
It is bleached.
What is chlorine used for?
The sterilisation of water, and also to make solvents and plastics such as PVC.
What is produced when chlorine and sodium hydroxide are reacted together?
Household bleach is formed.
What is sodium hydroxide used for?
In the production of soap.
What is hydrogen used for?
The manufacture of margarine.
What does brine contain?
Na+, Cl-, OH- and H+ ions.
What is the large scale electrolysis of brine a part of?
The chloro-alkali industry.
What is the chloro-alkali industry?
A global market which generates great profits.
How is hydrogen made during electrolysis of sodium chloride?
By reduction at the cathode:
2H+ + 2e- ----> H2
How is chlorine made during electrolysis of sodium chloride?
By oxidation at the anode:
2Cl- - 2e- ----> Cl2
What is oxidation?
Loss of electrons.
What is reduction?
A gain of electrons.
What remains in the solution after electrolysis of sodium chloride?
Sodium (Na+) and hydroxide (OH-) ions.