C10

Question 1

where do natural resources come from?

Answer 1

the sea, earth and air

Question 2

why are non-renewable resources finite?

Answer 2

because we extract them (fossil fuels etc) quicker than we can replace them. fossils take thousands of years to be produced but we extract them constantly, meaning they’ll run out.

Question 3

what does sustainable development mean?

Answer 3

economic development that takes into account the needs of the present without damaging the lives of the future.

Question 4

why can extracting resources be unsustainable?

Answer 4

because of the amount of energy used and the waste product.

Question 5

what are some methods scientists are using to extract copper form low-grade ores?

Answer 5

Bioleachning- bacteria are used to convert copper compounds in the ore into soluble copper compounds which can be extracted
Phytomining- growing plants in soil which contain copper. the plants are harvested, dried and burnt. the ash contains soluble copper compounds. which can be extracted using electrolysis.

Question 6

why is recycling materials such as metal a good idea?

Answer 6

• uses less energy than extracting materials
• conserves the finite amount of each metal in the earth
• cuts down on the amount of waste getting sent to the landfill.

Question 7

what do ‘life cycle assessments’ show?

Answer 7

the total environmental costs. it looks at every stage of a products life and is used to assess the impacts it would have on the environment.

Question 8

what are the four main stages of the life cycle?

Answer 8

• getting the raw materials
• manufacturing and packaging
• using the product
• product disposal

Question 9

what is potable water?

Answer 9

water thats safe to drink

Question 10

why is potable water not pure water?

Answer 10

because pure water would only contain H2O molecules whereas potable water contains a lot of dissolved substances.

Question 11

what is fresh water?

Answer 11

water that doesn’t have much dissolved in it. e.g rain water

Question 12

what is one way to process water to make it more fresh?

Answer 12

Filtration

• a wire mesh is used to filter out any twigs etc
• the sand and gravel filter out any more objects
• the water is then sterilised to kill any harmful bacteria or microbes. this can be done by bubbling chlorine gas through it or by using ozone/ultra violet light.

Question 13

what can distillation be used to do?

Answer 13

desalinate (remove salt from) sea water

Question 14

describe how you desalinate saltwater

Answer 14

distillation

• first you test the PH for the water using a PH metre. if it isn’t 7 already you may have to add some acid or alkaline to neutralise it.
• set up a Bunsen burner and a stand with a round bottomed flask (with a stopper to prevent loss of steam) on it which is connected to a condenser that leads to another beaker.
• heat up the water in the flask. it should evaporate and condense as steam.
• collect the water running out of the condenser into the beaker.
• retest the PH of the water with a PH metre to check it’s natural
• you can see if there was any salt in your initial sample by looking to see if there are crystals at the bottom of the round bottomed flask.

Question 15

how else (other than distillation) can sea water be treated?

Answer 15

by a process that uses membranes-like reverse osmosis that only allows water molecules to pass through so large ions and molecules are trapped

Question 16

why are distillation and reverse osmosis not practical for producing large quantities of fresh water?

Answer 16

because they require a lot of energy and therefor are very expensive.

Question 17

what are some sources for where waste sewage comes from?

Answer 17

• toilets and sewage
• baths and any time you flush water down the drain
• agricultural systems
• industrial processes

Question 18

describe the different stages of sewage treatment.

Answer 18

• before being treated, the sewage water is screened. this involves removing any large bits of material (twigs or plastic bags etc.)
• then it lies in a settlement tank and undergoes sedimentation- the heavier materials sink to the bottom and produce sludge while the lighter effluent floats to the top
• the effluent in the settlement tank is removed and treated by biological aerobic digestion. (air pumped through water which encourages bacteria to break down any organic matter)
• this is then released into the environment
• the sludge from the bottom of the settlement tank is removed and is broken down through anaerobic digestion.
• this sludge can be further treated to be used as fertilisers or natural gas in cookers.