Chemistry Using Earth's Resources March 2019

Question 1

What are the Earth’s resources? What are they used for?

Answer 1

• Rocks in the ground = Make metals from ores and buildings for stone, sand and brick (clay).
• Fuels such as coal, natural gas and oil = Fuel for transport, electricity, heating, clothes, plastic and some medicines
• Plants and animals = Food, buildings and medicines.
• Fresh water and sea water = Drinking, agriculture and energy.
• Air = Respiration and combustion.
• Sunlight = Energy and agriculture.
• Wind = Energy.

Question 2

What are finite and renewable resources?

Answer 2

Finite = A resource that cannot be replaced once it has been used.

Renewable = A resource that we can replace once it has been used.

Question 3

What is sustainable development?

Answer 3

Using resources to meet the needs of people today without preventing people in the future from meeting theirs.

Question 4

How can sustainable development be used for different resources?

Answer 4

Metals - Recycle materials instead of throwing them away and using more metal ores.

Fuels - Use bio-fuels (e.g. bio-diesel or ethanol) instead of fossil fuels.

Electricity - Use renewable energy sources instead of fossil fuels.

Question 5

How are different materials recycled?

Answer 5

Metals - Separated, melted then reformed.
Glass - Separated into colours, melted then remoulded.
Plastics - Separated into types, melted then remoulded.

Question 6

What is a life cycle assessment?

Answer 6

An examination if the impact of a product on the environment throughout it’s life.

Question 7

What is potable water?

Answer 7

Water that is safe to drink.

Question 8

What are the different types of water?

Answer 8

Pure water - Water that contains only water molecules and nothing else.
Potable water - Water that is safe to drink.
Fresh water - Water found in rivers, lakes, ice caps and glaciers.
Ground water - Fresh water in underground streams and in porous rocks.
Sea water - Water in the seas and oceans.
Waste water - Used water from homes, industry and agriculture.

Question 9

What are the contents of the different types of water?

Answer 9

Pure - Nothing
Potable - Low-levels of dissolved substances.
Fresh - Low-levels of microbes and low-levels of dissolved substances.
Ground - Microbes and low-levels of dissolved substances.
Sea - Microbes and high-levels of dissolved substances.
Waste - Microbes and high-levels of dissolved substances.

Question 10

What is desalination?

Answer 10

A process to remove dissolved substances from sea water.

Question 11

How does distillation work?

Answer 11

Sea water is heated so that it boils. The water molecules are turned to steam leaving behind the dissolved substances. The water vapour is then cooled and condensed.

Question 12

How does reverse osmosis work?

Answer 12

Sea water is passed through a semi-permeable membrane using pressure. The water molecules pass through the membrane but many of the dissolved substances cannot. This is the opposite of normal osmosis where the water would move in the opposite direction.

Question 13

What is an ore?

Answer 13

A rock from which a metal can be extracted for profit.

Question 14

What is an alloy?

Answer 14

A mixture of a metal with small amounts of other metals or carbon.

Question 15

What are different alloys made of? What are their purposes?

Answer 15

Bronze - Copper and Tin, used to make decorative objects.
Brass - Copper and Zinc, Used to make door fittings, water taps and instruments (trumpet etc).
Gold alloys - Gold and Silver/Copper/Zinc, used to make jewellery.
Steels - Iron and usually Carbon. Used to make cars, building frameworks, cutlery and tools.
Aluminium-Magnesium alloys - Aluminium and Magnesium. Used to make aeroplanes.

Question 16

What are corrosion and rusting?

Answer 16

Corrosion = The destruction of materials by chemical reactions with substances in the environment.

Rusting = The corrosion of iron or steel.

Question 17

What is the chemical equation for rusting?

Answer 17

Iron + water + oxygen –> Rust

Question 18

What two ways are used to stop the corrosion of materials?

Answer 18

Surface coating and sacrificial protection.

Question 19

What is sacrificial protection? How does it work?

Answer 19

Sacrificial protection is preventing a metal from corrosion by attaching it to a more reactive metal that corrodes in it’s place. E.g. zinc or magnesium blocks being attached to the hull of ships to prevent the corroding of the steel.

Question 20

What is surface coating? How does surface coating work?

Answer 20

Surface coating is when a substance is used to cover the material and act as a barrier. it prevents chemicals that cause corrosion from coming into contact with the material. E.g. Paint on a car or grease on a chain.

Question 21

What are the processes of bioleaching and leaching?

Answer 21

Bioleaching - The use of bacteria to produce soluble metal compounds from insoluble metal compounds.

Leaching - The use of dilute acid to produce soluble metal compounds from insoluble metal compounds.

Question 22

What is a leachate?

Answer 22

A solution produced by leaching or bioleaching.

Question 23

What is phytomining?

Answer 23

The use of plants to absorb metal compounds from soil as part of metal extraction.

Question 24

How is copper extracted?

Answer 24

Copper ores - low-grade copper ores are used as there a no longer high-grade ones. Bioleaching or leaching is then done to the ore to give a copper leachate. Electrolysis or a displacement reaction with scrap iron then takes place to give the copper metal.

Plants - Plants are grown in soil containing copper compounds. The plants are then burnt and bioleaching or leaching then takes place to give a copper leachate. Electrolysis or a displacement reaction with scrap iron then takes place to give the copper metal.

Question 25

What happens when dissolved copper compounds are made into copper metal?

Answer 25

Electrolysis - Two inert electrodes (e.g. graphite) are placed in the solution of copper compounds in an electrolysis circuit. Copper then forms at the negative electrode. Cu2+(aq) + 2e- –> Cu(s)

Displacement reaction - Scrap iron/steel is placed into the solution of copper compounds - Iron is more reactive than copper therefore the copper is displaced by the iron. Cu2+(aq) + Fe(s) –> Cu(s) + Fe2+(aq)

Question 26

What do the properties of a polymer depend on?

Answer 26

• Which monomer(s) they are made from.

- The conditions under which they are made.

Question 27

What is a thermosetting polymer? Thermosoftening polymer?

Answer 27

Thermosetting - A polymer with covalent bonds between the polymer chains that doesn’t soften or melt when heated. E.g. Superglue, Epoxy resins, melamine and Bakelite.

Thermosoftening - A polymer with no bonds between polymer chains that softens and melts when heated. E.g. Poly(ethene), PVC, Ploy(propene), Perspex, Teflon, Polyesters and Nylon.

Question 28

What is the Haber process?

Answer 28

A process in which nitrogen from the air and hydrogen from natural gas + steam react to make ammonia.

Question 29

What conditions are used in the Haber process? Why are they used?

Answer 29

Temperature = 450 degrees C
Pressure = 200 atm (10m underwater is 1 atm)
Catalyst = Iron (Fe)

The reaction is reversible and slow so these conditions are used to ensure there is a good yield and rate.

Question 30

What three elements are in fertilisers?

Answer 30

Nitrogen, Phosphorus and Potassium.