C19 Using The Earth's Resources

Question 1

What 2 ways can salty water be purified

Answer 1

• Distillation
• Reverse Osmosis

Question 2

Describe the process of distillation of salty water

Answer 2

Water heated to a vapour leaving salt behind and then cooled to form potable water

Question 3

Describe the process of reverse osmosis of salty water

Answer 3

Involves using membranes to separate the salts dissolved in the water. The water needs to be pressurised and the salty water corrodes the pumps. This makes it an expensive process.

Question 4

Define pure water

Answer 4

Every molecule in the substance is water

Question 5

Define potable water

Answer 5

Mostly water molecules, low levels of salts, safe levels of harmful microbes

Question 6

Define salty water

Answer 6

Mostly water molecules, dangerously high levels of salts, medium/high levels of harmful microbes

Question 7

Fresh water

Answer 7

Mostly water molecules, low levels of salts, medium/high levels of harmful microbes

Question 8

Describe the processes to get from sewage/waste water to sludge and effluent

Answer 8

• Screening and grit removal - Sewage passes through a metal grid that filters out large objects
• Sedimentation - The sewage is left so that solid (sludge) can settle out of the water as they sink to the bottom of the tank.
• Sludge and effluent can then be separated.

Question 9

How is sewage sludge treated

Answer 9

• Anaerobic treatment - Bacteria added to digest organic matter anaerobically
• Biogas produced
• Remaining sludge can be used as fuel

Question 10

How is sewage effluent treated

Answer 10

• Anaerobic treatment - Bacteria added to digest organic matter anaerobically
• Bacteria removed
• Can then be discharged back into rivers

Question 11

Describe the process of phytomining

Answer 11

• Plants are grown near to the metal ore so that the plant can be uptaken in the roots of the plant
• Harvest and burn the plants
• The ash contains the metal compound
• Use electrolysis to get the metal

Question 12

Describe the process of Bioleaching

Answer 12

• Grow bacteria near the metal ore.
• Bacteria produces leachate solutions that contains the metal compound
• The leachate can then be processed using electrolysis

Question 13

Name the 2 sustainable ways of extracting a metal from its ore

Answer 13

Phytomining + Bioleaching

Question 14

What is a Life cycle assessment (LCA)

Answer 14

A way of looking at the whole life of a product and assessing its impact on the environment and sustainability