PW

Question 1

What is Potable Water?

Answer 1

Water that you can drink

Chemists wouldn’t call it pure, as pure water only contains H2O molecules.

Question 2

What is the difference between pure water and potable water?

Answer 2

Potable water can contain lots of other dissolved substances

Pure water only contains H2O molecules.

Question 3

What are the two main sources of fresh water?

Answer 3

• Surface water (lakes, rivers, reservoirs)
• Groundwater (aquifers)

Fresh water is water that doesn’t have much dissolved in it.

Question 4

What is the process of filtration in water treatment?

Answer 4

A wire mesh screens out large twigs and gravel and sand beds filter out solid bits

This is the first step in making water safe.

Question 5

How is water sterilised?

Answer 5

By bubbling chlorine gas through it or using ozone or ultraviolet light

This step kills harmful bacteria or microbes.

Question 6

What is desalination?

Answer 6

The process of treating sea water to provide potable water

This is necessary in dry countries where surface or groundwater is inadequate.

Question 7

What is one method to desalinate sea water?

Answer 7

Distillation

This involves boiling the water and collecting the steam as liquid water.

Question 8

What are the steps to test water for sodium chloride?

Answer 8

• Conduct a flame test - yellow flame indicates sodium
• Add dilute nitric acid and silver nitrate - white precipitate indicates chloride

These tests help identify the presence of salt in water.

Question 9

What is reverse osmosis?

Answer 9

A process that uses membranes to separate water molecules from ions and larger molecules

It allows only water molecules to pass through, trapping contaminants.

Question 10

True or False: Both distillation and reverse osmosis require a lot of energy and are expensive.

Answer 10

True

This makes them impractical for producing large quantities of fresh water.

Question 11

Fill in the blank: The main salt in seawater is _______.

Answer 11

sodium chloride

Question 12

What should you check for after distilling water?

Answer 12

• Sodium chloride presence
• pH level

The distilled water should have no salt and a neutral pH of 7.

Question 13

What is the role of a pH meter in water treatment?

Answer 13

To test the pH of the water and ensure it is neutral

Neutral pH is important for safe drinking water.

Question 14

What happens to surface water in warm areas?

Answer 14

It tends to dry up first

This leads to a higher reliance on groundwater in those regions.