Cambridge IGCSE Chemistry - 0620 - Core Paper 3 2017 Winter Zone 3

The diagram shows the structures of five substances, A, B, C, D and E.

Answer the following questions using only the structures in the diagram. Each structure may be used once, more than once or not at all.

(a) Which structure, A, B, C, D or E,

(i) is a compound which is used as a fertiliser, .............................................................. [1]
(ii) is a diatomic molecule, .................................................................................................. [1]
(iii) contains chloride ions, ............................................................................................... [1]
(iv) is a gas which turns damp red litmus paper blue, ..................................................... [1]
(v) is an element? ............................................................................................................. [1]

(b) Structure A is sulfur dioxide. Sulfur dioxide is an atmospheric pollutant.

(i) State one source of sulfur dioxide. ............................................................................. [1]
(ii) Give one adverse effect of sulfur dioxide on health. .................................................. [1]

(c) An isotope of nitrogen is represented by the symbol $^{15}_{7}\text{N}$.
Deduce the number of protons, neutrons and electrons in this isotope of nitrogen.

number of protons ..........................................................................................................
number of neutrons ........................................................................................................
number of electrons ........................................................................................................ [3]

(a) Describe how Venus’ atmosphere differs from the Earth’s atmosphere. Give three differences. 1 ............................................................................................................................. ............................................................................................................................. 2 ............................................................................................................................. ............................................................................................................................. 3 ............................................................................................................................. .............................................................................................................................

(b) Describe a test for carbon dioxide. test ........................................................................................................................... result ..........................................................................................................................

(c) Venus’ atmosphere also contains small amounts of water and argon. (i) Water is a covalent compound. Complete the diagram to show • the arrangement of electrons in a molecule of water, • the symbols of the atoms present. Show outer shell electrons only.

(c) (ii) The melting point of argon is $-189$°C. The boiling point of argon is $-186$°C. What is the physical state of argon at $-200$°C? Explain your answer. ............................................................................................................................. .............................................................................................................................

(c) (iii) Argon is unreactive. Explain why argon is unreactive in terms of its electronic structure. ............................................................................................................................. .............................................................................................................................

(d) Clouds of sulfuric acid are present in Venus’ atmosphere. Sulfuric acid reacts with magnesium carbonate. $$\text{H}_2\text{SO}_4 + \text{MgCO}_3 \rightarrow \text{MgSO}_4 + \text{CO}_2 + \text{H}_2\text{O}$$ (i) Write the word equation for this reaction. .............................................................................................................................

(d) (ii) Calculate the relative molecular mass of sulfuric acid, $\text{H}_2\text{SO}_4$. Use your Periodic Table to help you. relative molecular mass = ................................

(e) Sulfur dioxide is found in the atmospheres of both Venus and the Earth. (i) State one use of sulfur dioxide. .............................................................................................................................

(e) (ii) Sulfur dioxide dissolves in water to form an acidic solution. Which one of the following pH values is acidic? Put a circle around the correct answer. pH 2 pH 7 pH 9 pH 14

The list shows some of the compounds used to manufacture ink.

calcium carbonate
ethanoic acid
iron(II) sulfate
potassium dichromate(VI)
sodium sulfate
sulfuric acid

(a) Which compound is present in limestone?
........................................................................................................................       [1]

(b) Hydrated iron(II) sulfate is heated gently.

$FeSO_4.7H_2O \rightarrow FeSO_4 + 7H_2O$

(i) Describe what you would see when a test-tube containing a small amount of hydrated iron(II) sulfate is heated gently.
........................................................................................................................         [1]

(ii) Describe a test for aqueous iron(II) ions.
test ........................................................................................................................
result ......................................................................................................................
[2]

(c) Iron(II) sulfate can be prepared by reacting an excess of iron with dilute sulfuric acid.

(i) Complete the chemical equation for this reaction.
$Fe + H_2SO_4 \rightarrow FeSO_4 + ext{............}$           [1]

(ii) Describe how you could remove the excess iron from the mixture formed.
........................................................................................................................         [1]

(d) (i) Complete the structure of ethanoic acid to show all of the atoms and all of the bonds.

[2]

(ii) Give one observation when aqueous ethanoic acid reacts with magnesium.
........................................................................................................................       [1]

(e) Black ink contains a mixture of different coloured dyes.
Draw a labelled diagram of the apparatus used to separate these different coloured dyes by chromatography.
[3]

(f) Blue ink was placed at the bottom of a beaker containing water.
After 2 days, a blue colour had spread throughout the beaker.


Explain these observations using the kinetic particle model.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
[3]

(a) Complete the table to show the electrical conductivity of solid diamond and molten sulfur. [2]
[Table_1]

(b) Give one piece of evidence from the table that shows that sulfur is a simple covalent substance. [1]
........................................................................................................................................................

(c) What information in the table shows that potassium bromide is an ionic compound? [2]
........................................................................................................................................................
........................................................................................................................................................

(d) (i) State one property of aluminium given in the table which makes it suitable for making aircraft. [1]
........................................................................................................................................................

(ii) Aluminium oxide is obtained from the ore bauxite.
What method is used to extract aluminium from aluminium oxide? [1]
........................................................................................................................................................

(e) Molten potassium bromide can be electrolysed.
Predict the products of this electrolysis at
the positive electrode (anode), ..........................................................................................
the negative electrode (cathode). .................................................................................... [2]

(f) (i) Which two statements describe the structure and bonding in diamond?
Tick two boxes. [1]

Diamond has ionic bonds. [ ]
Diamond has a giant structure. [ ]
Diamond is a simple molecule. [ ]
Diamond has covalent bonds. [ ]

(ii) Give one use of diamond. [1]
........................................................................................................................................................

Lead is extracted from an ore which contains lead(II) sulfide.
(a) The ore is first heated in air.
Balance the chemical equation for this reaction.
$$2\text{PbS} + ...... \text{O}_2 \rightarrow 2\text{PbO} + ...... \text{SO}_2$$ [2]

(b) The lead(II) oxide produced is then reduced with carbon.
$$\text{PbO} + \text{C} \rightarrow \text{Pb} + \text{CO}$$
(i) How does this equation show that the lead(II) oxide is reduced?
.............................................................. [1]
(ii) Lead is a metal in Group IV.
Iron is a transition element.
Give two physical properties that are typical of transition elements.
1 ..........................................................................
2 .......................................................................... [2]

(c) State the conditions needed for iron to rust.
............................................................................. [2]

(d) Iron from the blast furnace is converted into steel using oxygen and basic oxides.
(i) What is the purpose of the oxygen?
................................................................ [1]
(ii) Which one of these oxides is a basic oxide?
Put a circle around the correct answer.
carbon dioxide nitrogen dioxide potassium oxide sulfur trioxide
Explain your answer.
................................................................ [2]

(e) Steel is an alloy.
What is meant by the term alloy?
.............................................................................
............................................................................. [2]

(f) (i) Give one common use of mild steel.
................................................................ [1]
(ii) Give one common use of stainless steel.
................................................................ [1]

The diagram shows a fractionating column used for the fractional distillation of petroleum.

(a) On the diagram, write
• the letter X to show where the temperature in the fractionating column is highest,
• the letter B to show where bitumen is removed from the fractionating column. [2]
(b) Give the name of the fraction labelled F in the diagram. [1]
(c) Refinery gas contains methane, ethane and propane.
(i) Draw the structure of a molecule of ethane showing all of the atoms and all of the bonds. [1]
(ii) Methane can be converted to hydrogen by reaction with steam.
Balance the chemical equation for this reaction.
CH₄ + H₂O → CO + ......H₂ [1]
(iii) This reaction is endothermic.
What is meant by the term endothermic? [1]
(d) Some petroleum fractions are cracked to form different hydrocarbons.
Describe the process of cracking.
In your answer
• explain what is meant by the term cracking,
• state the conditions needed to crack hydrocarbons. [4]
(e) The table shows some properties of four alkanes.
[Table_1]
(i) How does the boiling point change as the number of carbon atoms in one molecule increases? [1]
(ii) Predict the boiling point of propane. [1]
(iii) Describe the arrangement and separation of the molecules in liquid butane. [2]