Waste water treatment

Humans use many different resources.

Water is an important natural resource.

What is meant by ‘potable water’?

Tick () one box.

Waste water needs treatment before the water is put back into rivers and the sea.

The first stage of waste water treatment is to pass the waste water through metal grids.

Why is the waste water passed through metal grids?

Tick () one box.

Clothes can be made from different materials.

Some clothes are made from wool and some clothes are made from poly(propene).

One sheep produces 4.5 kg of wool.

50 g of wool is needed to make a hat.

Calculate the number of hats that can be made from the wool of one sheep.

1 kg = 1000 g

Table 4 gives information about poly(propene) and wool.

Explain the advantages of using poly(propene) and of using wool for clothing.

After being used, clothes can be:

• given to other people to wear

• used to make insulation blocks for buildings.

Complete the sentences.

Choose answers from the box.

When clothes are given to other people to wear,

When clothes are used to make insulation blocks for buildings,

Poly(propene) is made from an alkene.

Alkenes are produced by cracking alkanes.

A high temperature is used for cracking alkanes.

Which two of the following can also be used to crack alkanes?

Tick () two boxes.

Which chemical is used to test for alkenes?

Tick () one box.

Water that is safe to drink is called potable water.

Compare how easily potable water can be obtained from:

• waste water (sewage)

• ground water (fresh water).

A scientist produced potable water from 150 cm³ of salty water.

Which process can be used to produce potable water from salty water?

Tick (✓) one box.

The salty water contains sodium chloride.

The scientist collected 2.40 g of sodium chloride from 150 cm³ of salty water.

Calculate the concentration of sodium chloride in grams per dm³

Water that is safe to drink is called potable water. Compare how easily potable water can be obtained from:

• waste water (sewage)

• ground water (fresh water).

A scientist produced potable water from 150 cm³ of salty water.

Which process can be used to produce potable water from salty water? Tick (✓) one box.

The salty water contains sodium chloride. The scientist collected 2.40 g of sodium chloride from 150 cm³ of salty water. Calculate the concentration of sodium chloride in grams per dm³

Fresh water contains low levels of dissolved salts.

Water reacts with anhydrous copper sulfate in a reversible reaction.

The word equation for the reaction is: water + anhydrous copper sulfate hydrated copper sulfate

How does the equation show that the reaction is reversible?

Complete the sentences. Choose answers from the box.

Figure 1 shows anhydrous copper sulfate in a sealed container.

Suggest one reason why anhydrous copper sulfate is kept in a sealed container.

Sodium chloride dissolves in water to form sodium chloride solution.

Draw one line from each substance to the description of the substance. Substance Description of substance

Name the process used to obtain solid sodium chloride from sodium chloride solution.

Two processes used to obtain potable water from fresh water are:

• filtering

• sterilising.

Give one reason why each process is used.

Which type of water is the easiest to obtain potable water from? Tick (✓) one box.

Which of the following is the first stage of waste water treatment? Tick (✓) one box.

This question is about pollutants.

Waste water has harmful substances removed before being released into the environment. Complete the sentences. Agricultural waste water requires the removal of harmful

Industrial waste water may require the removal of harmful

How is sewage sludge treated before being released into the environment? Tick (✓) one box.

Hydrocarbons are used to make polymers. Polymers are used to make plastic bags. In one year 8.0 billion plastic bags were used. The next year there was a charge for plastic bags and only 1.3 billion plastic bags were used. Calculate the percentage decrease in the number of plastic bags used.

Oxides of nitrogen are pollutants formed in car engines.

Give one problem oxides of nitrogen cause.

Figure 3 shows the mass of oxides of nitrogen produced from car engines from 1986 to 2016.

Suggest why the mass of oxides of nitrogen produced from car engines increased and then decreased.