C10- Using Resources- Paper 2

Question 1

What is potable water?

Answer 1

-Water that has been treated and is safe to drink
- it isn’t pure as it does have other substances dissolved in it
- for it to be potable is has to have a pH of 6.5-8.5

Question 2

Describe the steps used to treat fresh water to make it potable. [2 marks]

Answer 2

• the water is filtered using wire mesh and using filter beds of sand and gravel
• the filtered water is then sterilised using chlorine/ ozone/ UV light

Question 3

Describe the treatment of seawater- distillation.

Answer 3

-first neutralise the water
-heat up the water until it evaporates
-It will then enter the condenser as steam
-the sudden drop in temperature will cause it to condense back into liquid
-the water is collected
-then test the pH of the water again to check its still neutral

Question 4

Describe the treatment of seawater- reverse osmosis.

Answer 4

Water passes through a membrane that only allows water molecules to pass through so lager molecules and ions are trapped and separated from the water.

Question 5

Why are distillation and reverse osmosis used less than the filtration method?

Answer 5

Because both distillation and reverse osmosis use loads of energy so are very expensive and not practical for producing large quantities of water.