GCSE OCR A – Knowledge Test

C5 – Chemicals of the Natural Environment

Name……………………………………….. Date…………………

C5.1 What types of chemicals make up the atmosphere?

1. The atmosphere (air) that surrounds the Earth is made up many gases. Some of these gases are in large amounts and others are in relatively small amounts.

Put the below gases into the correct column of the table.

nitrogen water vapour oxygen argon carbon dioxide

large amounts small amounts

[1]

2. Complete the table by filling in the names of the gases that make up the atmosphere today.

[1]

3. Give the chemical formula for the atoms and molecules that make up the gases in the air.

[1]

name of gas approximate percentage in atmosphere

78%

21%

1%

0.04%

name of gas formulaargon

carbon dioxide

nitrogen

oxygen

4. Circle the correct term.

Most non-metal elements and most compounds between non-metal elements have

molecular / ionic / metallic structures. [1]

5. Circle the correct term.

molecular elements and compounds with small molecules have low / high melting and

boiling points

6. Here are some properties of five substances.

substance melting point boiling pointelectrical

conductivity of solid

hardness at room

temperature1 high high poor very hard2 high high good soft3 high high good hard4 high high poor hard5 low low poor not applicable

Which substance is most likely to be molecular substance?

……........................... [1]

7. Gases in the air have low boiling points.

Explain why.

Use ideas about

size of molecules

forces between molecules.

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8. Explain why pure molecular compounds do not conduct electricity

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9. Explain how a covalent arises.

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10. Tick (√) the correct box.

Molecules havestrong

covalent bonds between atoms, weak

and havestrong

weak forces between molecules. weak

[1]

11. Draw a 3D representation of CH4.

[1]

C5.2 What reactions happen in the hydrosphere?

1. Complete the below sentence.

The Earth’s hydrosphere (oceans, seas, lakes and rivers) consists mainly of ......................... with

some dissolved compounds, called ......................... [1]

2. Solid ionic compounds form crystals because the ions are arranged in a regular ..........................[1]

3. Explain how ionic bonding arises.

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4. Here are some properties of five substances.

substance melting point boiling pointelectrical

conductivity of solid

hardness at room

temperature1 high high poor very hard2 high high good soft3 high high good hard4 high high poor hard5 low low poor not applicable

Which substance is most likely to be an ionic substance?

……........................... [1]

5. Describe what happens to the ions when an ionic crystal dissolves in water.

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6. Explain why ionic compounds conduct electricity when dissolved in water

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7. Work out the formulae for the salts in seawater by using the charges given for each ion.

name of compound formula of positive ion

formula of negative ion formula

sodium chloride Na+ Cl –

magnesium chloride Mg2+ Cl –

sodium sulfate Na+ SO42-

potassium chloride K+ Cl –

potassium bromide K+ Br –

[5]

8. Complete the below sentence.

Explain how ions in an ionic compound can be ...................................and ...................................

because they have distinct properties and they form compounds with distinct properties

9. What is the name of the insoluble compound made on mixing two solutions of ionic compounds?

……..................................................................................................................................................[1]

10. When barium ions, Ba2+, react with sulfate ions, SO42-, a white precipitate of barium sulfate, BaSO4,

is made.

Write a balanced ionic equation for this reaction. Include state symbols in your answer.

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11. Tap water contains chloride ions. Describe a test you could use. Use the data sheet to help.

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12. Some metal ions can be identified in solution by adding alkali because they form insoluble hydroxides with characteristic colours.

Give the formula of some of the negative ions that can be tested.

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13. Write down the colours of the precipitates formed when the below ions react with dilute sodium hydroxide.

You may wish to use the data on the first page to help you.

ion colour of precipitatecalcium, Ca2+

copper, Cu2+

iron (II), Fe2+

iron (III), Fe3+

zinc, Zn2+

[5]

14. Some negative ions in salts can be identified in solution by adding a reagent that reacts with the ions to form an insoluble solid.

Give the formula of some of the negative ions that can be tested.

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15. Write down the observation when the below ions react with each of the stated chemicals.

You may wish to use the data on the first page to help you.

ion test observation

carbonate, CO32- add dilute acid

chloride, Cl – add dilute nitric acid, then add silver nitrate

bromide, Br – add dilute nitric acid, then add silver nitrate

iodide, I– add dilute nitric acid, then add silver nitrate

sulfate, SO42- add dilute acid, then add barium

choride or barium nitrate[5]

C5.3 What types of chemicals make up the Earth’s lithosphere?

1. Name the two parts of the Earth where minerals are found.

……............................................. and ................................................. [1]

2. Which element are diamond and graphite composed of?

……..................................................................................................................................................[1]

3. Here are some properties of five substances.

substance melting point boiling pointelectrical

conductivity of solid

hardness at room

temperature1 high high poor very hard2 high high good soft3 high high good hard4 high high poor hard5 low low poor not applicable

Which substance is most likely to be diamond?

……........................... [1]

4. The table shows some similarities and differences in the properties of graphite and diamond.

graphite diamond

melting point 3650oC 3560oC

boiling point 4830oC 4830oC

solubility in water insoluble insoluble

electrical conductivity does not conduct does not conduct

hardness soft, flakes easily very hard

Use ideas about their structures to explain these similarities and differences.

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5. Give the three most abundant elements in the Earth’s crust

……........................................ , ………....................................... and ........................................... [1]

6. The table below has data about the abundances of elements in a sample of a rock.

element percentage (%)silicon 30oxygen 50calcium 5carbon 5

other elements

What percentage of the rock is ‘other elements’?

……........................... [1]

7. Much of the silicon and oxygen is present in the Earth’s crust as a compound.

Give the name of this compound.

……............................................................... [1]

8. Silicon dioxide is another giant covalent compound.

Which substance are the properties of silicon dioxide most similar to?

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C5.4 How can we extract useful metals from minerals?

1. State what is meant by the term ‘ore’.

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2. Explain why in copper mining, large amounts of ore need to be mined?

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3. Zinc, iron and copper are metals that can be extracted by heating their oxides with carbon.

Write simple word equations for these reactions. One has been done for you.

zinc oxide + carbon → zinc + carbon dioxide

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4. Complete the below sentence.

When a metal oxide loses oxygen it is ............................., while the carbon gains oxygen and is

.............................

5. State why some metals cannot be reduced by carbon

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6. Zinc oxide reacts with carbon to form zinc and carbon dioxdide.

Write a word equation for this reation.

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7. Complete the table below.

2 ZnO + C → 2 Zn + CO2

number of molecules …….number of formulas

……. ……. …….

[2]

8. Put numbers on the lines to balance the equation for this reaction.

............. PbS + ............. O2 → ............. PbO + ............. SO2

9. Iodine, I2, reacts with sodium metal. Sodium iodide is made.

Write a balanced symbol equation for this reaction.

Include state symbols.

........................................................................................................................................................ [1]

10. Give the state symbols for the below states.

solid ........... liquid ........... gas ........... aqueous ........... [1]

11. Use the Periodic Table to obtain the relative atomic masses for the elements in the table below.

element relative atomic masses

aluminium

copper

oxygen

[1]

12. Use relative atomic masses to calculate relative formula masses for the compounds in the table below.

compound relative atomic masses

Cu2O

CuO

CuCO3

[1]13. Balculate the percentage mass of copper, Cu, in copper oxide, CuO.

[1]

14. Lead metal can be extracted from heating lead oxide, PbO, with carbon.

2PbO + C → 2Pb + CO2

What is the maximum mass of lead that can be extracted from 446 g of lead oxide.

……………………………….. g [3]

15. Explain what is meant by the term ‘electrolysis’.

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16. Give an example of an electrolyte

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17. Describe what happens to the ions when an ionic crystal melts

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18. Complete the below sentence.

During electrolysis, metals form at the ..................................... electrode and non-metals form

at the .....................................electrode. [1]

19. Describe the process that aluminium is extracted from aluminium oxide

........................................................................................................................................................ [1]

20. During electrolysis of molten aluminium oxide, positively charged aluminium ions gain electrons from the negative electrode to become neutral atoms.

Complete the equation to show the changes that take place at this electrode.

Al3+ + ............ e– → ............ [1]

21. During electrolysis of molten aluminium oxide, negatively charged oxide ions lose electrons to the positive electrode to become neutral atoms which then combine to form oxygen molecules.

Complete the equation to show the changes that take place at this electrode.

2O2– → ............ + ............ e– [1]

22. In an electrolysis experiment, some solid lead bromide is heated until it melts. The electric current is then turned on.

What happens to the lead ions and the bromide ions?

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23. Iron is important because its properties are useful.

Draw a straight line to link each property to why it is useful.

property

good electrical conductor

high melting point

malleable

strong

[3]

24. Metals are a giant structure held together by strong bonds.

State the type of bonding.

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25. The diagram shows the structure of a metal.

(i) Use the diagram to help you describe the structure of this metal.

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(ii) Suggest why this structure allows metals to be good conductors of electricity.

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why is it useful?can be used to make roof supports

can be hammered in to different shapes

can be used to make lightning conductors

can be used to make barbeques

can be used to make magnets

26. Extracting copper from rock might harm the environment. Which answer explains why?

Put a tick (√) in the correct box next to the correct answer..

copper is found in other rocks

copper is a group 1 element

there would be a lot of waste rock left over

the rock contains calcium

[1]