Topic 10- using resources

What is the haber process

The industrial production of ammonia from nitrogen and hydrogen

What is the use of ammonia

used to make nitrogen based fertilisers which allow the food growth we need

What is the Source of nitrogen

Air (78% nitrogen)

What is the source of hydrogen

Hydrocarbons eg methane

What type of reaction is the haber process

Exothermic and reversible

What are the industrial conditions for the haber process

Temperature 450 degrees, pressure 200 atm, catalyst iron

Why is temperature 450 for haber process

Compromise between maximum yield and speed of reaction

Why is pressure 200 atm for haber process

Higher pressure favours forward reaction moving equilibrium towards ammonia, also increases rate of reaction

Why is an iron catalyst used in haber process

Increases rate of reaction, reaches equilibrium faster, without catalyst temperature would have to be raised reducing percentage yield and increasing energy costs

Describe how haber process works

Hydrogen and nitrogen is fed into top left of machine to mix together, in reaction vessel conditions are kept at 450 degrees and 200 atm and gases are free to pass over the iron catalyst, some of the nitrogen and hydrogen react together to form ammonia but because it’s a reversible reaction the mixture still contains lots of nitrogen and hydrogen so reactants and products need to be separated by passing pipe into condenser which cools down gassed ammonia till it condenses into liquid ammonia

What is potable water

Water that’s safe to drink

Is potable water pure or impure

Impure, contains other dissolved substances

What are requirements for potable water

Low levels of dissolved substances, pH between 6.5-8.5, no microorganisms

What is fresh water

Water that doesn’t have much dissolved in it

What are the two types of fresh water

Surface water- bodies of water exposed to surface eg lakes, reservoirs, rivers

Ground water- bodies of water found underground eg acquirers (permeable rock that traps water)

Pros and cons of surface water

Easy to access, replaced frequently, can dry up if it’s hot and sunny

Describe the process of treatment of fresh water

Filtration- wire mesh screens out large things, bed of sand and gravel filters out smaller solids. Sterilisation- bubbling chlorine gas through it, exposing to ozone or UV light kills microbes

What is desalination

Extracting potable water from sea water

What are the two ways desalination can be done

Distillation, reverse osmosis

Why is desalination impractical for producing large quantities of water

Requires lots of energy making it expensive

Describe the process of reverse osmosis

Salty water is passed through membrane which only allows water molecules to pass so large molecules and ions gets trapped and are separated from the water

What are the three type of waste water sources

Domestic (household waste), agricultural systems (nutrient run off, animal waste), industrial (factories that make and use chemicals

Describe process of waste water treatment

Screening- remove large materials, sedimentation- let sewage sit in settlement tank, heavier solids sink to bottom to produce sludge, less dense effluent floats at top, aerobic digestion- effluent removed and treated, air pumped through to encourage aerobic bacteria to break down any organic matter. Anaerobic digestion- sludge broken down by anaerobic digestion, methane gas produced in process and sludge exposed to uv radiation

What can the left over sludge be used as in east water treatment

Fertiliser

What are the stages in a LCAs

Getting raw materials, manufacturing and packaging, using the product, product disposal

What are the problems with life cycle assesments

Some environmental impacts require judgements meaning LCAs aren’t fully objective, some LCAs are selective (only show some of the environmental impacts of a product) so can be biased/misleading

What are NPK fertilisers

Formulations containing salts of nitrogen, phosphorus and potassium to increase the productivity of crops

What are fertilisers

Formulations that replace or provide more of nitrogen, phosphorus and potassium in solis in order to increase crop yield ad the crops can grow faster and bigger

What are the three main elements needed by plants

Nitrogen, phosphorus and potassium

What can ammonia be used to form

Nitric acids or ammonium salts

What is the product of reacting ammonia with an acid

Ammonium salts

What is the product of reacting ammonia with water

Nitric acid

What process is used to produce nitrogen based fertilisers

Haber process

Describe the process of producing fertilisers in industry

Ammonia gas is added directly to giant vats containing highly concentrated nitric acid. This result in a very exothermic reaction. The heat released is used to evaporate water from the mixture to make a very concentrated ammonium nitrate product

Describe the process of producing fertilisers in a lab

•Reaction is carried out on a smaller scale by titration and crystallisation. •Ammonia solution used

•reactants are at much lower concentration than in industry so less heat is produced by reaction and is safer for a person to carry out.

•after titration, mixture needs to be crystallised to give pure ammonium nitrate crystals

Why is crystallisation not used in industry

It’s very slow

What can be mined and used as a source of potassium

Potassium sulphate, phosphate rock and potassium chloride

Can phosphate rock be used directly as a fertiliser

No

Reacting phosphate rock with different types of acids produces…

…soluble salts which can be used as fertilisers

What does phosphate rock reacted with nitric acid produce

Phosphoric acid and calcium nitrate

What does phosphate rock reacted with sulfuric acid produce

Calcium sulphate and calcium phosphate (known as single superphosphate)

What does phosphate rock reacted with phosphoric acid produce

Calcium phosphate (product of this reaction can be called triple superphosphate)

What does reuse mean

Using a product more than once for the same purpose or putting a used product to a new purpose

What does recycling mean

Using waste materials to make new products

What are the advantages of recycling metals

Only uses a small fraction of the energy needed to mine and extract new metal, energy is expensive so it saves money, finite amount of each metal in earth so recycling conserves these resources, cuts down on amount of rubbish sent to landfills

How are metals recycled

By melting them and casting them into the shape of a new product

How is glass recycled

Glass is crushed and then melted to be reshaped for use in glass products eg bottled or for insulation eg glass wool

What happens to glass before it’s recycled

It’s repeated by colour and chemical composition