Waste water treatment

This question is about water.

Hydrogen gas reacts with oxygen gas to produce water.

Water is decomposed into hydrogen gas and oxygen gas using electricity.

Which two words describe the reaction between hydrogen gas and oxygen gas?

Tick (✓) two boxes.

Water molecules break down into hydrogen ions and hydroxide ions.

The equation for the reaction is:

Which sentence describes this reaction at equilibrium?

Tick (✓) one box.

Water collected from rivers is used in the home for drinking and flushing toilets.

Water used in the home must be potable.

Potable water is safe to drink.

Waste water produced after use in the home is called sewage.

Figure 12 shows how water is collected from rivers and returned to rivers after use.

Explain what happens to water in Process A and in Process B in Figure 12.

Do not refer to use of water in the home.

This question is about water.

Hydrogen gas reacts with oxygen gas to produce water.

Water is decomposed into hydrogen gas and oxygen gas using electricity.

Which two words describe the reaction between hydrogen gas and oxygen gas?

Tick (✓) two boxes.

Water molecules break down into hydrogen ions and hydroxide ions.

The equation for the reaction is:

Which sentence describes this reaction at equilibrium?

Tick (✓) one box.

Water collected from rivers is used in the home for drinking and flushing toilets.

Water used in the home must be potable.

Potable water is safe to drink.

Waste water produced after use in the home is called sewage.

Figure 3 shows how water is collected from rivers and returned to rivers after use.

Explain what happens to water in Process A and in Process B in Figure 3.

Do not refer to use of water in the home.

This question is about water.

Sewage is waste water. Sewage contains organic matter.

Describe how sewage is treated to remove organic matter.

Sea water and ground water are treated to make them potable. Table 5 shows information about the composition and treatment of sea water and of ground water.

Sea water is desalinated during Process 1. Which pair of concentrations could represent X in Table 5 ? Tick (✓) one box.

Explain why the concentrations of sodium ions and of chloride ions in the ground water in Table 5 are unchanged by Process 1.

Explain why the ground water in Table 5 requires Process 2 before the water is safe to drink.

After treatment the ground water in Table 5 is sold by a company as pure water. The ground water in Table 5 is not chemically pure because the water contains sodium ions and chloride ions.

Suggest what the company means by ‘pure’.

Chlorine is also used to treat some ground water. Describe the test for chlorine gas. Give the result of the test.

This question is about water.

In the UK, potable (drinking) water is produced from different sources of fresh water.

Explain how potable water is produced from fresh water.

A different country has:

• very little rainfall

• a long coastline

• plentiful energy supplies.

Suggest one process this country could use to obtain most of its potable water.

Waste water is not fit to drink.

Treatment of waste water produces two substances:

• liquid effluent

• solid sewage sludge.

Draw one line from each substance to the way the substance is processed.

Substance Process

Table 6 shows information about the disposal of processed solid sewage sludge in the UK in 1992 and in 2010.

Calculate the percentage of processed solid sewage sludge that was burned in 2010.

Give your answer to 3 significant figures.

Use Table 6.

Suggest one reason why the total mass of processed solid sewage sludge increased between 1992 and 2010.

Between 1992 and 2010 the proportion of processed solid sewage sludge used as fertiliser increased.

Suggest two reasons why.

This question is about water.

In the UK, potable (drinking) water is produced from different sources of fresh water. Explain how potable water is produced from fresh water.

A different country has:

• very little rainfall

• a long coastline

• plentiful energy supplies.

Suggest one process this country could use to obtain most of its potable water.

Waste water is not fit to drink. Treatment of waste water produces two substances:

• liquid effluent

• solid sewage sludge.

Draw one line from each substance to the way the substance is processed.

Substance Process

Table 1 shows information about the disposal of processed solid sewage sludge in the UK in 1992 and in 2010.

Calculate the percentage of processed solid sewage sludge that was burned in 2010. Give your answer to 3 significant figures. Use Table 1.

Suggest one reason why the total mass of processed solid sewage sludge increased between 1992 and 2010.

Between 1992 and 2010 the proportion of processed solid sewage sludge used as fertiliser increased. Suggest two reasons why.