Something that can reform at a similar or faster rate than we use it 

Fertiliser: before we used animal excrement. Now we use the haber process to form them from ammonia.

What is a natural product supplemented / replaced by synthetic products in agriculture?

Only contains H2O molecules, no other dissolved substances 

Ground water can be filtered and sterilised whereas salty water needs to be desalinated 

Treatment of ground water vs salty water 

Test pH - if not 7, neutralise via titration. Then test for NaCl using knowledge from chemical analysis topic. Heat flask - water will evaporate, leaving salt in flask. The steam will condense and be collected. Retest for NaCl and pH. 

Salty water passed through a membrane that only allows H2O molecules to pass through. Large ions/molecules are trapped by the membrane and therefore separated from water. 

Dissolved salts - can be harmful. Microbes - can cause illness 

What must potable water have low levels of? Why?

Sewage treatment - more processes than treating fresh water but uses less energy than desalination. Can be used in areas where there isn’t freshwater. 

Explain how easily potable water can be obtained from waste, compared to other processes 

Depends on location. Warm areas, ground water needs to be filtered and sterilised. In very dry countries, there’s not enough sometimes so seawater will need to be desalinated instead 

Explain how easily potable water can be obtained from the ground 

Desalination/reverse osmosis : needs loads of energy = expensive. Not practical for producing large quantities 

Evaluate the process of potable water being obtained from salt water 

Growing plants in soil containing copper. They will take up low grade copper and store it, then be harvested, dried and burned to extract. The ash contains soluble copper compounds from which the copper can be extracted via electrolysis or displacement with iron

Using bacteria to extract ore. It converts copper compounds in ore to be soluble, separating copper in the process. Leachate contains copper ions which can be extracted via electrolysis or displacement  

Solution produced via the process of bio leaching 

Traditional methods damage the environment. These methods have a smaller impact but they’re also slower.

Evaluate impacts / benefits of biological methods to extract metal  

 looking at every stage of a product’s life to assess its impact on the environment 

PLASTIC - manufactured using crude oil through fractional distillation, cracking and polymerisation. Waste is reduced because there are other uses. They are reusable and recyclable. PAPER - raw material is timber. Pulped timber requires lots of energy and produces lots of waste. Can only be used once but are biodegradeable 

Compare LCAs for shopping bags made of plastic and paper. 

Effects of some pollutants are harder to give numerical values to. Not objective bc depend on person carrying out the assessment so can be biased. Selective LCAs can be written to deliberately support the claims of companies 

Air pollution, climate change, water pollution, solid waste disposal - environmental damage. AND will eventually run out so we can’t use them forever

What are the issues relating to using limited resources to generate electricity?

Uses lots of energy, scars landscape, produces waste, destroys habitats (therefore can reduce biodiversity)

What are impact of obtaining raw materials from the earth?

Iron nail in a boiling tube with water - won’t rust. (boil water to remove oxygen and have oil on top to stop air from getting in). Iron nail in empty boiling tube (so will have just air) - won’t rust - also have CaCO3 to absorb any water from the air. If you have both air and water in the tube, the nail will rust.

Describe an experiment to show that air and water are both needed for rusting 

When a metal reacts with substances in the environment and gradually gets destroyed 

Prevent rusting by placing a more reactive metal with iron so the air / water reacts with that metal instead 

Iron + Water + Oxygen —-> Hydrated Iron (III) oxide 

What is the equation for formation of rustV

By spraying it with a coat of zinc. It’s protective but even if it’s scratched, it’ll act as a sacrificial metal. 

Painting/plastic coating. Electroplating - using electrolysis to reduce metal ions into an iron electrode which coats iron with a layer of metal that won’t corrode. Oiling/greasing moving parts.

High - lots of carbon (0.22-2.5%). Low - less carbon (0.1-0.3%)

Made of copper and tin. Bronze is harder than copper. Used for medals and statues 

Made of copper and zinc. More malleable than bronze. Used where low friction is required eg water taps and door fittings 

Why are gold alloys used rather than pure gold

Low density. Harder as alloys than metal. Used for aircraft manufacture 

From ethane - moderate temp. high pressure. flexible. used in bags and bottles 

Descibe how LDPE is formed and it’s uses

From ethane. low temp. pressure. catalyst. more rigid. used in water tanks and drain pipes 

Descibe how HDPE is formed and it’s uses

Thermosoftening - individual polymer chains entwined with weak forces. (able to melt and remould) Thermosetting - monomers that form cross links between polymer chains. solid structure. (don’t soften when heated- strong/hard/rigid)

Explain difference between thermosoftening and thermosetting polymers in terms of structure 

Soda lime - made by heating a mixture of limestone, sand, sodium carbonate until it melts. Borosilicate- higher melting point than soda lime. Made of sand and boron trioxide. 

Compare soda lime glass and borosilicate glass 

Ability to mould when wet and then hardened makes it ideal for pottery and bricks

Fibres of glass embedded in a matrix made of polymer. Low density like plastic but strong like glass 

polymer matrix - long chains of carbon bonded together OR nanotubes. strong / light. aerospace and sportscar manufacture 

Aggregate embedded in cement. Very strong. used in building material 

Natural composite or cellulose fibres held bonded by a matrix of lignin  

What gas is the only alkali in gas form? 

Nitrogen- air. Hydrogen- reacting methane (natural gas) with steam 

State the raw materials in the haber process and where they come from 

Reactants passed over iron catalyst. Temperature of 450°C and pressure of 200a. Because it’s reversible, some ammonia can convert back, reaching dynamic equilibrium eventually. Ammonia formed as gas. Cools in condenser and liquifies, then is removed. Unused reactants are recycled. 

Describe the process of manufacturing ammonia

Write the balanced equation for the reaction in the haber process 

The forward reaction is exothermic so increasing the temperature will shift the equilibrium the wrong way. The yield of ammonia is therefore greater at a lower temperature. BUT low temp means slower rate of reaction so 450°C is a compromise between max yield and the speed of reaction 

Why is a temperature of 450°C used in the haber process?

Pressure moves equilibrium to the products side because there are more molecules on that side which increases yield. It’s set as high as possible without making it too expensive or dangerous to build + maintain. 

Name what’s produced when phosphate rock is treated with nitric acid 

Calcium sulphate and calcium phosphate (known as single superphosphate)

Name what’s produced when phosphate rock is treated with sulfuric acid 

Calcium phosphate (known as triple super phosphate)

Name what’s produced when phosphate rock is treated with phosphoric acid 

More widely available, easier to use, don’t smell, just enough of each nutrient

Why are formulated fertilisers better than using manure?

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Entire using resources, paper 2 topic for GCSE chemistry (triple)

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Using resources - GCSE chemistry 

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GCSE Chemistry: Using Resources - Notes, Questions & Answers

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GCSE Chemistry: Using Resources - Notes, Questions & Answers

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