Using Resources Flashcards
Paper 2 - C10
What do we use the Earth’s resources for?
-Warmth
-Shelter
-Food
-Transport
How do agriculture help us use the Earth’s resources more efficiently?
-Cotton which is produced from a plant is an example as modern agriculture allows us to grow enough cotton to meet the needs of the world.
-Humans also plant trees which can be used for timber or fuel for example many power station now run on biofuels such as woodchips.
What does it mean by ‘Finite’?
That resources cannot be replaced as quickly as they are being used.
What are some examples of a finite resource?
-Fossil fuels
-Metals
What does it mean by ‘Renewable’?
That resources can be replaced as quickly as we use them.
What are some examples of a renewable resource?
-Wood
-Soil
Why is it important that human activities are sustainable?
We can meet our needs without preventing future generations from meeting theirs.
Why does chemistry play an important role in how we use resources?
-Artificial fertilisers allow us to grow more food with the land available.
-Helps us to provide water that is safe to drink.
-Processes such as phytomining and bioleaching help us to extract metals more efficiently.
What is the difference between potable and pure water?
Potable water is water that is safe to drink whereas pure water contains no dissolved substances at all but potable does contain dissolved substances in small amounts.
What is the main source of potable water in the UK?
Rain water as it contains low levels of dissolved substances.
How do we produce potable water?
-First we choose a good source of fresh water e.g. a river.
-We then pass the water through filter beds. That is to remove materials such as leaves and suspended particles.
-Finally, the water is sterilised to kill microbes. In the UK we use chlorine to sterilise potable water.
What process do we use to make sea water into potable water? And Why?
Desalination as sea water has very high levels of dissolved minerals.
What does desalination do to sea water to help make it into potable water?
Desalination reduces the levels of dissolved minerals down to an acceptable level for potable water.
What are the ways to carry out desalination?
-Distillation
-To pass the water through membranes which is called reverse osmosis
What are the problems with the ways to carry out desalination?
Both processes require very large amounts of energy which makes them very expensive.
What do we use water for?
-Drinking
-Personal hygiene
-Flushing toilets
-Washing clothes
-Agriculture
-In industry e.g. in making paper and chemicals
What does waste water contain?
-Large amounts of organic molecules e.g. from urine and faeces.
-Harmful microorganisms such as bacteria.
What are the steps in which waste water is treated before being released back into the environment?
-First, the sewage is screened by passing through a mesh which removes solids and pieces of grit.
-Now the sewage is allowed to settle in large sedimentation tanks and this produces a liquid effluent and a semi-solid sludge which sinks.
-The sludge is taken away and digested by anaerobic bacteria.
-In the absence of oxygen, these bacteria produce biogas which can be burned for electricity.
-The digested sludge can now be used as fertilisers for farming.
-Next, air is bubbled through the liquid effluent which allows aerobic bacteria to multiply.
-In the presence ox oxygen, the aerobic bacteria digest the organic molecules and harmful microorganisms.
-After this stage, the liquid effluent can be safely discharged into nearby rivers or the sea.
What does liquid effluent contain?
Large amounts of organic molecules and harmful microorganisms.
What is the easiest way to produce potable water?
Its to use ground water from aquifers
Why does the water from aquifers need to be tested carefully?
As sometimes the aquifers can be polluted e.g. with fertilisers from farms.
Why is potable water directly made from waste water in places with scarce water supply?
Because it takes many purification steps and it can take a great deal of energy making it expensive.
Why is copper useful?
Because it is used in electronic equipment such as phones
Why is it difficult to extract copper economically from low grade ores?
Because there is only a very small amount of copper
What happens in phytomining to extract metal compounds?
-First, plants are grown on land containing the metal compound we want.
-These plants absorb the metal compound and they concentrate it in their tissue.
-The plants are then harvested and burned.
-At the end, the ash contains a relatively high concentration of the metal compound.
What happens in bioleaching to extract metal compounds?
-First, bacteria is mixed with the low grade ore.
-The bacteria carry out chemical reactions and they produce a solution called a leachate.
-At the end, the leachate contains the metal compound that we want.
How do we extract the metal from the compound after we use phyomining or bioleaching?
-We could displace the metal with a metal with higher reactivity e.g. Iron can displace copper.
-Also we could use electrolysis.
Why are phytomining and bioleaching good to use?
-Theses methods do not involve digging, transporting and disposing of large amounts of rock unlike in traditional mining.
-And they allow us to economically extract metals from low-grade ores and its important as the Earth’s resources of metal ores are limited.
What is it meant by a life-cycle assessment?
A life-cycle assessment attempts to put a number on the environmental impact of a product.
What is the environmental impact of producing plastic/polymers? And how?
-Polymers such as plastics are produced using crude oil.
-The oil has to be extracted from the ground and then transported to oil refineries and the hydrocarbons have to be separated then cracked and the polymer has to be produced which takes a great deal of energy.
-A lot of that energy will be generated by burning fossil fuels which leads to climate change.
What is the environmental impact of extracting metals? And how?
-Extracting metals also takes a huge amount of energy.
-The ore has to be dug out of the mine and transported for processing, the metal then has to be extracted from the ore and this can produce large amounts of toxic waste products.
-Once we have produced our raw materials, we can then manufacture our product, package it and transport it all of these stages will require energy and they may release harmful waste products.
What is the environmental impact of products during their lifetime?
-In the case of a toy, this could involve a large number of batteries and producing batteries releases a large amount of toxic waste.
What is the environmental impact of products during their disposal?
-Many modern products contain a number of harmful chemicals and these chemicals have to be disposed of carefully and again this may require a lot of energy and it also takes energy to transport used products for disposal.
How are plastic bags produced from?
Using chemicals from crude oil
How are paper bags produced from?
Wood from trees
How can the production of plastic and paper bags be harmful to the environment?
-Extracting crude oil can be harmful to habitats e.g. if there is an oil leak and felling trees for wood is also extremely destructive to habitats such as forests.
-Both crude oil and wood need to be chemically processed and in both cases this requires a large amount of energy and releases waste products making paper also require huge amounts of water.
What are the similarities and differences between plastic and paper bags?
-Plastic shopping bags are strong and are often reused as bin liners whereas paper bags tend to tear as they are0n’t that strong and are often only used once before being thrown away. (Difference)
-At the end of their lives, both plastic bags and paper bags have to be transported either for recycling or to landfills. (Similarity)
-Paper bags are often heavier than plastic bags so they can take more energy to transport. (Difference)
-Plastic is non-biodegradable and it is not broken down by microorganisms however paper breaks down quickly especially when wet and because plastic bags are non-biodegradable they remain in the environment for a very long time which means they fill up landfills and are a major form of litter. (Difference)
What are the problems with a life-cycle assessment?
-We can measure the use of water and energy we can also measure the production of some waste products but we cannot always be certain of how damaging these are to the environment which means in some cases we have got to make estimates or value judgments and they may not always be accurate.
-Life-cycle assessments can be biased e.g. to support claims by advertisers.
Why is quarrying and mining bad for the environment?
Quarrying produces large amounts of dust and destroys habitats and mining can release harmful chemicals into the environment.
Why is it important that we try to reduce our need for raw materials?
To help save limited resources and energy. Also it will reduce the amount of waste that we produce and have a less harmful effect on the environment.
