Chemistry - The Earth's Resources 2

Water that looks colourless and clear may contain microorganisms. Which of the following are ways in which the water could be made potable? You can select as many as you like.

• Passing through filter beds made of sand and gravel

• The addition of chlorine or ozone to sterilise the water

• Passing UV light through the water

• Leaving the water in the Sun for 2 hours

Water can be purified by distillation, but this requires lots of energy, why is this a problem?

• Takes too long

• Costs too much

• Doesn't always work

Converting salty water to potable, usable water is called ______________.

Which treatment comes after screening in water treatment works?

• Primary treatment

• Secondary treatment

• Final treatment

Which method of water purification would be best suited to a country in the Middle East which has a large amount of fossil fuel reserves?

Why is it not safe to drink a distilled water sample in the lab?

• It might still be salty

• It might be contaminated because the apparatus might not have been cleaned properly before the practical.

• It won't taste very nice

Which of the following is the correct description of potable water? Tick one answer.

• Pure water

• Water with a pH between 4.5 and 6.5

• Water that is safe to drink

• Water with a high concentration of salt

In the picture you will see the equipment used in distillation (you saw this is KS3 as well) Name the component labelled B in the diagram.

• thermometer

• condenser

• Round bottomed flask

• Bunsen burner