Potable Water

Question 1

What is potable water ?

Answer 1

Water that is safe to drink

Question 2

Is potable water pure ?

Answer 2

No

Question 3

What is the PH of potable water ?

Answer 3

6.5-8.5

Question 4

What are the three criteria of potable water ?

Answer 4

1. Needs to be free of harmful microbes
2. Water has PH of 6.5-8.5
3. Levels of dissolved substances need to be fairly low

Question 5

What are the three criteria of pure water ?

Answer 5

1. No dissolved substances inside
2. PH of 7
3. BP is fixed at 100*c

Question 6

What are the two supplies of water ?

Answer 6

Ground water and sea water

Question 7

What are surfaces water sources ?

Answer 7

• lakes
• Rivers
• reservoirs
  Bodies of water that are exposed at their surface

Question 8

Where are ground water sources?

Answer 8

Aquifers: Permeable rock under the ground that trap water

Question 9

What is the benefit of using a surface water sources such as a lake ?

Answer 9

Easy to access
Replaced frequently by the rain

Question 10

What is a limitation of using a surface water source ?

Answer 10

If it’s sunny it can dry up so in warmer areas they rely on ground water

Question 11

How do we treat water ?

Answer 11

1. Filter through filter beds and wire mesh: removes solids
2. Passed through bed of sand and gravel which filters the smaller solids
3. Sterilise it to kill any microbes

Question 12

What are the three methods of sterilisation ?

Answer 12

1. Bubbling chlorine gas through it
2. Exposing it to Ozone
3. Exposing it to ultraviolet light

Question 13

If a country doesn’t have a good supply on fresh water what might they rely on ?

Answer 13

Desalination which extracts potable water from sea water

Question 14

What is a benefit of using sea water?

Answer 14

Limitless supply

Question 15

What are the two teachniqes for desalination ?

Answer 15

Reverse Osmosis

Distillation

Question 16

What are the negatives of using desalination ?

Answer 16

Both methods, distillation and reverse osmosis, require lots of energy
Really expensive

This makes them impractical for producing large quantities of water

Question 17

How do we desalinate water through distillation ?

Answer 17

Same as normal distillation where the water is boiled then condensed to give us distilled water
Except
It’s in larger quantiles of sea water being boiled and the apparatus will look different

Question 18

How does reverse osmosis work ?

Answer 18

The salty water is passed through a membrane which only allows for water molecules to pass through
Therefore
The larger ions and molecules get trapped and separated leaving us with pure distilled water