Global Reserves & Potable Water (AQA GCSE Chemistry: Combined Science)

Exam Questions

2 hours18 questions
1a1 mark

Humans use the Earth's resources to survive everyday life.

Which of the following do we not obtain from the Earth's resources.

Tick (✓) one box.

Shelter  
Sunlight  
Warmth  
Food  
Transport  
1b4 marks

In addition to the natural resources available, humans have developed synthetic products.

Sort the following items into the correct columns in Table 1.

  • Rubber
  • Ceramics
  • Poly(ethene)
  • Wood

Table 1

Natural resources Synthetic products
   
   
   
1c2 marks

Table 2 shows some of Earth's natural resources and the time taken for them to form.

Table 2

Natural resource Time taken to form in years
Wood 2 to 30
Cereal grains 0.5
Crude oil 6 x 107


Which one of the natural resources is said to be a finite resource? Explain your answer.

1d3 marks

It is becoming increasingly more important for chemists to design processes and materials that are sustainable.

Complete the sentence using words from the box.

current previous compromising
             future                     allowing


Sustainable development meets the needs of ____________________ generations without ____________________ the ability of ____________________ generations to meet their own needs.

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2a1 mark

Water can be made potable by treating water from lakes and rivers.

What does potable water mean?

2b1 mark

The first stage in treating water from rivers and likes removes solid particles such as soil, twigs and small pebbles.

What is the name of the process used in this stage?

2c1 mark

Another stage of water treatment is to sterilise the water.

What could not be used to sterilise the water?

Tick (✓) one box.

Fluoride  
Chlorine  
Ozone  
Ultraviolet light  
2d3 marks

Sea water can be made safe to drink by desalination.

Distillation can be used to desalinate sea water.

The equipment that could be used to desalinate sea water is shown in Figure 1.

Figure 1

aqa-gcse-10-1e-tq2d-distillation-of-sea-waterGive the names of the components A to D.

Label Name
A  
B  
C  
D  
E  
2e1 mark

Desalination of sea water is an expensive process so it is only used to produce large quantities of drinking water when there is no alternative supply.

Give one reason why the process is so expensive?

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3a1 mark

Water samples can be analysed in the laboratory to measure pH and the amount of dissolved solids.

pH of the water samples can be determined using either a pH meter or universal indicator.

Give one reason why using a pH meter is the preferred method.

3b1 mark

A student analysed four water samples to find the pH and the amount of dissolved solids in each water sample.

They used a pH meter to find the pH and the method below to find the amount of dissolved solids.

  • Weigh an empty evaporating basin
  • Pour 20 cm3 of a sample of water into the basin
  • Heat the basin gently over a Bunsen burner until the majority of water has evaporated
  • Leave until all the water has evaporated
  • Reweigh the evaporating basin containing the dissolved solids in

How could the student calculate the amount of dissolved solids in 20 cm3 of water using the results obtained from this method?

3c3 marks

The results obtained from the analysis of the four water samples are shown in Table 1.

Table 1

Water sample pH Mass of dissolved solids in 20 cm3 of water
A 8.2 0.72
B 4.2 0.03
C 7.0 0.00
D 6.3 0.02


The student knew that sample D was tap water taken from the laboratory.

Draw one line from each of the other water samples, A, B and C, to the source of the water sample.

Use the results from the analysis shown in Table 1.

zsb-jGdS_watersamples

3d
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1 mark

What mass of dissolved solid would be present in a 100 cm3 sample of water sample B?

Tick (✓) one box.

0.03 g  
0.15 g  
0.30 g  
1.50 g  

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4a2 marks

Domestic uses and industrial processes produce vast quantities of waste water which must be treated before being released into the environment.

Which two substances need to be removed from sewage and agricultural waste water?

Tick (✓) two boxes.

Fluoride  
Harmful microbes  
Dissolved salts  
Organic matter  
4b2 marks

Which two substances need to be removed from industrial waste water?

Tick (✓) two boxes.

Harmful chemicals  
Harmful microbes  
Sodium ions  
Organic matter  
4c4 marks

Sewage needs several stages of treatment. Figure 1 shows these different stages.

Label the processes A and B and the names of the two substances produced by sedimentation X and Y.

Use words from the box below.

aerobic sludge effluent
screening            anaerobic                     sterilisation


Figure 1

aqa-gcse-10-1e-tq4c-sewage-treatment-flowchart

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5a1 mark

The Earth's resources of copper ore are limited.

New processes to extract copper from low-grade ores have been developed.

What is meant by the term 'low-grade ores'?

Tick (✓) one box.

The copper produced from these ores does not have a high economical value  
They contain very low percentages of copper compounds  
The copper they contain is impure  
5b2 marks

Phytomining and bioleaching are two processes that have been developed that can extract copper from low-grade ores.

Draw one line from each method of extraction to the substance that is used to extract copper.

6Msbp3lO_phyto-and-bioleaching

5c3 marks

Complete the sentences about phytomining and bioleaching.

Choose the correct words from the box below.

       ash              an unreactive metal                         sediment
leachate            electrolysis  copper oxide


Phytomining results in the production of ____________________ that contains metal compounds.

Bioleaching produces ____________________ solutions that contain metal compounds.

The metal compounds produced can be processed further to obtain the metal, for example, copper can be extracted from copper compounds by displacement by scrap iron or ____________________.

5d1 mark

Phytomining and bioleaching reduce the need to mine for copper-rich ores.

Give one disadvantage of mining.

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1a6 marks

Figure 1 shows a typical greenhouse used to generate heat for growing small batches of fruit and vegetables. 

Figure 1 

aqa-gcse-10-1m-q1a-greenhouse

The frame can be made either from wood or aluminium.

The table below provides some relevant information about both wood and aluminium.

  Aluminium Wood
Raw material Non-renewable Renewable
Useful lifetime in years 50 20
Mass of frame in kg 2 80
End of useful life Can be recycled Can be used as fuel


Use the information to evaluate the use of wood and aluminium for making greenhouse frames.

1b2 marks

Making greenhouse frames from recycled aluminium is more sustainable than from aluminium extracted from aluminium ore.

Give two reasons why this is the case. 

1c2 marks

The windows used in greenhouses can be made from either glass or polymers.

The table below provides some relevant information about both these materials.

  Polymer Glass
Cost in £ per m2 28 20
Density in g / cm3 1.2 2.8
Effect of sunlight Loses colour over time No effect


U
se the information from the table to suggest and explain one advantage of using polymer windows rather than glass windows.

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2a2 marks

Water from a local lake in the UK is used to provide drinking water to a local community.

The water requires treatment before being suitable for consumption.

What are the two main steps used to treat lake water?

In your answer provide a reason for each step.

2b3 marks

Explain why producing drinking water from waste water is more complicated than it is to produce it from water in lakes.

2c1 mark

Water that is safe to drink is called potable water.

Potable water is not pure water.

State the difference between potable water and pure water.

2d2 marks

Some countries produce drinking water from sea water but this is a costly enterprise.

Explain why producing water from sea water is so expensive.

2e2 marks

State how the water produced from sea water could be tested to show that it was pure.

Give the expected results if the water was pure.

2f
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2 marks

A student used the following method to find out how much solid was dissolved in a sample of sea water:

  • Measure the mass of an empty evaporating basin
  • Measure 20 cm3 of the sea water sample using a measuring cylinder and pour into the evaporating basin
  • Heat the evaporating basin on a tripod and gauze using a Bunsen burner until the solids start to form and the majority of water has evaporated
  • Leave the basin until all of the water has evaporated
  • Measure the mass of the cooled evaporating basin 

The results the student obtained are:

  • Mass of empty evaporating basin = 21.35 g
  • Mass of evaporating basin and dry solid residue = 21.96 g

Calculate the mass of solid dissolved in 1000 cm3 of the sea water.

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31 mark

During the treatment of waste water, a liquid called effluent is produced.

Which process does it undergo?

  • Sedimentation

  • Anaerobic digestion

  • Screening

  • Aerobic digestion

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4
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1 mark

A student was investigating the mass of dissolved solids in spring water.

The student carried out the following steps:

  • Measure the mass of an empty evaporating basin
  • Add 50 cm3 of spring water
  • Heat up the water sample until it evaporates
  • Reweigh the evaporating basin containing the solid

The following results were recorded:

  • Mass of empty evaporating basin = 19.56 g
  • Mass of evaporating basin and dry solid residue = 20.23 g

What is the mass of solid dissolved in 1 dm3 of the spring water?

  • 0.67 g

  • 13.4 g

  • 33.5 g

  • 67.0 g

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5a2 marks

This question is about the extraction and use of metals.

Many everyday domestic and industrial items are made from iron.

Haematite is an ore of iron and contains the compound iron oxide, Fe2O3.

Explain the meaning of the term ore.

5b1 mark

Iron is produced by reacting Fe2O3 with carbon inside a blast furnace.

What type of reaction takes place?

5c2 marks

The word equation for this reaction is:

iron oxide      +       carbon        →        iron    +    carbon dioxide

Complete and balance the symbol equation below.

___Fe2O3          +          ___C           →     __________   +      __________

5d3 marks

Figure 1 shows the ways in which iron is extracted, used and recycled. 

Figure 1

aqa-gcse-10-1m-q3d-metal-recycling-flow-chart

Explain why the recycling of iron is necessary for sustainable development. 

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6a3 marks

This question is about alternative methods of extraction of copper.

Copper has many uses but is largely used in the production of electrical wiring.

Phytomining and bioleaching are alternative methods of extracting metals like copper.

Explain why alternative methods are necessary, commenting on how they affect the sustainability of extracting copper.

6b4 marks

Phytomining is the technique used to obtain copper from areas of land that contain very low percentages of copper compounds.

Describe the process of phytomining.

6c5 marks

Bioleaching is another technique used to extract copper from low grade ores.

Describe the process of bioleaching.

6d1 mark

State one disadvantage of these alternative methods compared to the traditional methods of metal extraction.

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71 mark

Copper can be extracted from low grade ores using bioleaching. 

A leachate solution is produced.

Which process is used to extract the copper from the leachate solution?

  • Distillation

  • Cracking

  • Displacement

  • Fermentation

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8
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1 mark

A student carried out a number of chemical tests on a sample of water to determine whether it contained sodium chloride. 

Which sample contained sodium chloride? 

  Flame test colour Add sodium hydroxide solution Add nitric acid and silver chloride solution Add hydrochloric acid and barium chloride 
A brick red no reaction yellow precipitate  no reaction
B yellow no reaction  white precipitate no reaction
C yellow no reaction cream precipitate  no reaction
D no colour green precipitate no reaction white precipitate 

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    1a4 marks

    It is becoming increasingly more important for chemists to develop manufacturing processes sustainably.

    Explain what is meant by sustainable development and how chemists play a role in sustainable development.

    Include an example in your answer.

    1b6 marks

    Carrier bags are often made from poly(ethene) but chemists have developed bags that can be made from other materials including one made from corn starch.

    Table 1 shows some information about the bags made from these materials.

    Table 1

      Bags made from poly(ethene) Bags made from corn starch
    Raw material Crude oil Plants
    Energy demand during production Moderate High
    Biodegradable No Yes
    Recyclable Yes Limited


    Evaluate the use of poly(ethene) and corn starch to make carrier bags, commenting on the sustainability of the production and disposal of both types of bags.

    Use the information in Table 1 and your understanding of LCAs to help you answer.

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    2a1 mark

    In the UK, potable water is produced from fresh water.

    Lakes and rivers are common sources of fresh water.

    Name another source of fresh water.

    2b4 marks

    Explain how drinking water is obtained from fresh water.

    2c2 marks

    Pure water can be obtained from sea water by the process of distillation.

    Explain why this is not used in the UK to produce drinking water.

    2d3 marks

    Reverse osmosis is another method of desalination of fresh water which is a process that uses a membrane as shown in Figure 1.

    Figure 1

    ts-NORqP_reverse-osmosis

    Suggest what the role of the membrane is in reverse osmosis and why this is an expensive process.

    Use Figure 1 to help you answer.

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    3a6 marks

    Potable water contains dissolved solids which are not harmful to drink in small quantities.

    Describe a method that could be used to find out the amount of dissolved salts contained in different water samples.

    3b3 marks

    A student investigated the amount of dissolved solids contained in different water samples.

    They also measured the pH of the water samples.

    Their results are shown in Table 1.

    Table 1

    Water pH Mass of dissolved solid in g/dm3
    Tap water 6.6 0.4
    Sea water 7.9 28.0
    Tap water from area affected by acid rain 5.9 0.6


    What would you expect the pH and mass of dissolved solids to be in a sample of pure water?

    Explain your answer.

    3c2 marks

    How could the student confirm that the final water sample is pure?

    3d2 marks

    Calculate the mass of the dissolved solids in 100 cm3 of sea water?

    Use the results in Table 1.

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    4a2 marks

    Waste water, including sewage and agricultural waste water, requires treatment before being released into the environment.

    Name two substances that must be removed from waste water prior to it being released.

    4b2 marks

    Treatment of waste water produces liquid effluent and solid sewage sludge.

    What two processes does waste water go through in order to produce the effluent and sludge?

    4c2 marks

    How are the sewage sludge and liquid effluent treated?

    4d
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    3 marks

    Table 1 shows some information about how the treated solid sludge was disposed from one sewage treatment plant in 2000 and 2020.

    Table 1

    Mass of treated solid sludge in tonnes
    Year Used as fertiliser Sent to landfill Other Total
    2000 56 22 55 132
    2020 152 2 39 193


    Calculate the percentage of treated solid sludge that was sent to landfill in 2000.

    Give your answer to 3 significant figures.

    4e3 marks

    The total mass of treated solid sludge increased from 2000 to 2020 and the proportions of how the sludge was disposed of changed.

    Suggest one reason for the increase in the total mass of treated solid sludge and two reasons for the changes in the proportions of the disposal methods.

    Use Table 1 to help you answer.

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    5a2 marks

    Copper is extracted from copper ores. The traditional method of extracting copper is by quarrying and then heating in a furnace.

    In recent years, copper is being extracted from ores that contain a lower percentage of copper compounds.

    Suggest two reasons why.

    5b3 marks

    Bioleaching is a new method that can be used to extract copper from land that contains low percentages of copper compounds.

    Bioleaching uses bacteria to produce copper sulfate solution.

    Copper can be obtained from copper sulfate solution by electrolysis.

    Give another method of how copper can be obtained from copper sulfate solution and explain why this method can extract copper from its compound.

    5c6 marks

    Phytomining is another biological method to extract copper from low-grade copper ores.

    Land where copper ore has been mined contains very low percentages of copper compounds.

    Plants are grown on this land, absorbing the copper compounds through their roots.

    The process of phytomining is shown in Figure 1.

    Figure 1

    aqa-gcse-10-1h-tq5c-phytomining

    Use the information in Figure 1 and your knowledge to evaluate the method of phytomining and the traditional method to extract copper.

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