c14

Question 1

what do humans use the earth’s resources for?

Answer 1

warmth, shelter, food and transport

Question 2

what is sustainable development

Answer 2

development that meets the needs of current generations without compromising the ability of future generations to meet their own needs

Question 3

what should good drinking water for humans have?

Answer 3

• pH between 6.5 and 8.5
• dissolved substances should be in low quantites
• be free of bacteria and harmful microbes

Question 4

potable water

Answer 4

water that is safe to drink

Question 5

potable water and pure water

Answer 5

potable water contains dissolved substances and therefore it is not pure water

Question 6

how is water considered fresh

Answer 6

when it has low levels of dissolved substances - eg rainwater

Question 7

surface water

Answer 7

water from reservoirs, lakes and rivers

Question 8

ground water

Answer 8

aquifies which are porous rocks that store water underground

Question 9

how is most potable water produced

Answer 9

• choosing an appropriate source of fresh water
• passing the water through filter beds
• sterilising.

Question 10

examples of steralising agents for potable water treatment

Answer 10

chlorine, ozone, ultra violent light

Question 11

desalination

Answer 11

done when fresh water supplies are limited, so sea water or salty water is needed.
involves the treatment of seawater to remove the salt by distillation or reverse osmosis

Question 12

reverse osmosis

Answer 12

salt water is put through a semi-permeable membrane and only water molecules can pass through it. this happens as the membrane stops larger molecules and ions passing through.

Question 13

problems with desalination

Answer 13

it is an expensive process as it consumes large amounts of energy and is not ideal when producing large quantities of fresh water

Question 14

water purification and analysis practical steps

Answer 14

• use universal indicator paper to determine the pH of the water sample
• weigh empty evaporating basin to 2dp
• add 25 cm3 of water sample A into evaporating basin
• heat evaporating basin on a tripod and gauze using a Bunsen burner until the solids start to form and the majority of water has evaporated
• leave for the remaining water to evaporate off
• weigh the cooled evaporating basin again and calculate the mass of the solids that were dissolved in the water.

Question 15

Why does waste water require treatment

Answer 15

To remove organic matter and harmful chemicals

Question 16

Describe the steps of sewage treatment

Answer 16

1. Screening and grit removal
2. Sedimentation.
3. Aerobic digestion.
4. Anaerobic digestion.

Question 17

Screening and grit removal

Answer 17

to remove large materials like twigs and plastic bags

Question 18

Sedimentation

Answer 18

Water stands still while heavier solid sinks to the bottom creating sewage sludge while lighter matter floats to the top (effluent)

Question 19

Aerobic respiration sewage treatment

Answer 19

Effluent is removed. Air is pumped into water to encourage breakdown of organic matter and microbes by aerobic bacteria

Question 20

Anaerobic respiration sewage treatment

Answer 20

Used to break down sewage sludge from the bottom of sediment tank. Bacteria break it down releasing methane gas. Methane is used as a source of energy and leftover digested waste as a fertilizer

Question 21

Methods of extracting copper ores and advantages

Answer 21

Bioleaching and phytomining. They avoid mining methods of digging moving and disposing of large amounts of rock

Question 22

Phytomining

Answer 22

Plants are grown in areas known to contain metals needed in the soil.
They absorb the metal compounds. The harvested and then burnt to produce ash. This contains the metal compounds which can then be extracted by displacement or electrolysis

Question 23

Bioleaching

Answer 23

It uses bacteria to produce leachate solutions that contain metal compounds. They can then be obtained by displacement or electrolysis

Question 24

Why are life cycle assessments used

Answer 24

To assess the environmental impact of products in each of the stages

Question 25

What are the stages in the life cycle assessment

Answer 25

Extracting and processing raw materials
Manufacturing and packaging
Use an operation during its lifetime
Disposal at the end of its useful life including transport and distribution at each stage