Using Resources Flashcards
Renewable resources
Finite resources
Potable water
Water that is safe to drink
Contains dissolved substances such as salts and microbes
Pure water
Has no dissolved salts
Sterilising agents
Chlorine
Ozone
Ultraviolet light
Desalination
Removing salt from a solvent
Desalination - distillation
Sea water is heated until it boils
The salt remains in the liquid, and the steam is pure water
The steam is cooled and condensed to make potable water
Disadvantages of distillation
Requires a lot of energy to heat up and condense
The waste water is very salty and hard to dispose of in a environmentally friendly way
Desalination - reverse osmosis
Water is put under high pressure and passed through a membrane which has tiny pores (holes) in it
The pores allow water molecules through but prevents most ions and molecules from passing through
Disadvantages of reverse osmosis
Requires expensive membranes
Produces a large volume of waste water = low efficiency
Waste water treatment
Screening - to remove large particles, e.g. grit
Sedimentation - solids sink to form sewage sludge and effluent (liquid) which remains on top
Sludge is dried and anaerobically digested by microbes, removing organic matter
The dried sludge is used as fertilisers and also produces biogas which generates electricity
Effluent is aerobically digested by microbes, removing organic matter and harmful microbes
Analysis and purification of water required practical
For each sample of water, test the pH using a universal indicator
For each sample of water, pour 50 cm3 into a clean pre-weighed evaporating basin
Heat gently over a Bunsen burner, tripod and gauze until no liquid remains
Allow to cool, then weigh the evaporating basin again and calculate the mass of the solid that remains in the evaporating basin
Extracting copper from ores - smelting
A method of producing refined goods using heats
Advantage - high concentrations of Cu can be extracted
Disadvantages - high amounts of energy needed = expensive, charcoal produces carbon dioxide
Extracting copper from ores - bioleaching
Bacteria absorbs copper compounds, producing solutions called leachates
Advantage - very clean method
Disadvantage - only works with small amount of copper
Extracting copper from ores - phytomining
Crops are planted onto the soil with a small amount of copper, the plants absorb the copper via the roots, then the plant is burnt to produce ash with copper ions
Advantage - plants are renewable
Disadvantage - produces carbon dioxide
Extracting copper from ores - electrolysis
When compounds are broken down into smaller substances
Disadvantages - uses a lot of electricity = expensive
Life cycle assessments (LCAs)
They assess the environmental impact of products in each of these stages
- extracting and processing raw materials
- manufacturing and packaging
- use and operation during its lifetime
- disposal at the end of its useful life, including transport and distribution at each stage
Corrosion
The destruction of materials by chemical reactions with substances in the environment
E.g. rusting (air and water is needed)
Preventing corrosion
Corrosion can be prevented by applying a coating that acts as a barrier, such as greasing, painting or electroplating
Aluminium has an oxide coating that protects the metal from further corrosion
Alloys
A mixture of two or more elements, at least one of which is a metal
Bronze
An alloy of copper and tin
Used as propellers for ships, bells
Brass
An alloy of copper and zinc
Used for coins, musical instruments
Gold
An alloy with silver, copper and zinc
Used for jewellery
Steel
An alloy of iron that contain specific amounts of carbon and other metals
High carbon steel is strong but brittle
Low carbon steel is softer and more easily shaped
Stainless steel
An alloy containing chromium and nickel is hard and resistant to corrosion
Production of glass
Made by heating a mixture of sand, sodium carbonate and limestone
Borosilicate glass, made from sand and boron trioxide, melts at higher temperatures than soda-lime glass
Production of ceramics
Made by shaping wet clay and then heating it in a furnace
Low density poly(ethene) - LDPE
Flexible, unreactive, can be made into films
Most carrier bags, bubble wrap
Random arrangement of molecules
High density poly(ethene) - HDPE
Strong, flexible, resists shattering, resists chemical attack
Plastic bottles, pipes, buckets
More uniformed arranged of molecules
Thermosoftening polymers
Melt when they are heated
Thermosoftening plastics do not have covalent bonds between neighbouring polymer molecules, so the molecules can move over each other when heated and the plastic melts
Used in many everyday plastics
Thermosetting plastics
Do not melt when heated
They tend to char and burn when heated, but they are resistant to much higher temperatures than thermosoftening plastics
Used to make electrical plugs
Composite materials
Material made from two or more different materials with contrasting properties
Matrix
The substance that binds the reinforcement together in a composite material
Reinforcement
Fibres or other material that make up the bulk of a composite material.
Reinforced concrete
A composite material that is reinforced by steel and has a matrix of concrete
Fibreglass
A composite material that is reinforced by glass fibres and has a matrix of polymer resin
Carbon fibre reinforced polymer
A composite material that is reinforced by carbon fibre chips and has a matrix of polymer resin
Chipboard
A composite material that is reinforced by wood chips and has a matrix of resin glue
Haber process
Used to manufacture ammonia, which can be used to produce nitrogen-based fertilisers
The raw materials for the Haber process are nitrogen and hydrogen
Source for nitrogen
Nitrogen is obtained from the air
Source for hydrogen
Hydrogen is obtained by reacting natural gas (mostly methane) with steam, or from cracking oil fractions
Process of the Haber process
The purified gases are passed over a catalyst of iron at a high temperature (about 450°C) and a high pressure (about 200 atmospheres)
Some of the hydrogen and nitrogen react to form ammonia
The reaction is reversible so some of the ammonia produced breaks down into nitrogen and hydrogen
On cooling, the ammonia liquefies and is removed
The remaining hydrogen and nitrogen are recycled
NPK fertilisers
Compounds of nitrogen, phosphorus and potassium are used as fertilisers to improve agricultural productivity
NPK fertilisers are formulations of various salts containing appropriate percentages of the elements
Treatment of phosphate rock
Ammonia + nitric acid → ammonium nitrate
Ammonium hydroxide + nitric acid → ammonium nitrate + water
Ammonia + sulfuric acid → ammonium sulfate
Ammonium hydroxide + sulfuric acid → ammonium sulfate + water
