Cambridge IGCSE Chemistry - 0620 - Core Paper 3 2014 Summer Zone 1

(a) Choose from the list of substances below to answer the following questions.

calcium oxide
carbon dioxide
carbon monoxide
copper
hydrogen
magnesium
methane
oxygen
water

Each substance may be used once, more than once or not at all.
Which substance:
(i) releases hydrogen when it reacts with steam, ................................................................................................................. [1]
(ii) is produced at the cathode when concentrated aqueous sodium chloride is electrolysed, ................................................................................................................. [1]
(iii) is a product of the incomplete combustion of carbon, ................................................................................................................. [1]
(iv) is used in electrical wiring, ................................................................................................................. [1]
(v) is manufactured by heating limestone? ................................................................................................................. [1]

(b) Complete the following sentences about the Periodic Table of elements using words from the list below.

argon colour density sodium
one similarity trend seven

Chlorine, bromine and iodine are elements in Group .............................. of the Periodic Table.
These elements show a .............................. in ...................... down the group.
They all react rapidly with .............................. to form ionic compounds. [4]

Describe how Thomson’s model of the atom differs from our present ideas of the structure of an atom. [3]

(b) Lithium has two naturally-occurring isotopes. These can be written as: $$^{6}_{3}Li$$ and $$^{7}_{3}Li$$ (i) Describe the difference between these isotopes. [1] (ii) Isotopes can be radioactive or non-radioactive. State one industrial use of radioactive isotopes. [1]

(c) Lithium is in Group I of the Periodic Table. The table shows some properties of the Group I elements. [Table_1] Deduce: - the melting point of lithium, .......................................................... °C - the atomic radius of potassium ..................................................... nm [2]

(d) Lithium reacts with water. An alkaline solution and a colourless gas are formed. (i) Complete the word equation for this reaction. lithium + water → .............................. .............................. + .............................. [2] (ii) What is the most likely pH of the alkaline solution? Put a ring around the correct answer. pH 2 pH 5 pH 7 pH 13 [1]

(e) Draw the electronic structure of a potassium atom. [2]

The table shows some fractions obtained from the distillation of petroleum.

[Table_1]

(a) What is the relationship between the number of carbon atoms and the boiling points of the fractions? ...........................................................................................................................[1]

(b) State the names of two petroleum fractions not given in the table.
................................................ and ................................................................. [2]

(c) Two of the compounds present in refinery gas are methane and ethane.

(i) Draw the structure of ethane. Show all atoms and bonds. [1]

(ii) Complete the dot and cross diagram of methane to show all the electrons.
[2]

(d) Refinery gas also contains propane. Propane can be cracked in the presence of a catalyst to form hydrogen.

(i) Complete the symbol equation for this reaction.
$C_3H_8 \rightarrow \text{............} + H_2$ [1]

(ii) A catalyst is one condition needed to crack an alkane. State one other condition needed to crack an alkane.
................................................................................................................ [1]

The diagram shows the changes of state when tin vapour is cooled slowly to room temperature.

(a) Explain what happens to the arrangement and motion of the atoms during these changes.
...........................................................................................................................................................................................
...........................................................................................................................................................................................
...........................................................................................................................................................................................
...........................................................................................................................................................................................
........................................................................................................................................................................................... [4]
(b) Tin is a metal in Group IV of the Periodic Table. How many electrons does tin have in its outer shell?
........................................................................................................................................................................................... [1]
(c) State one physical property of tin.
........................................................................................................................................................................................... [1]
(d) The table below describes the reaction of some metals with dilute hydrochloric acid.
[Table_1]
Put these metals in order of their reactivity.
least reactive _________________________ most reactive
_________________________ [2]
(e) Tin is extracted by heating tin(IV) oxide with carbon.
(i) Complete the symbol equation for this reaction.
SnO$_2$ + ......C $ o$ Sn + ......CO [2]
(ii) State one adverse effect of carbon monoxide on health.
........................................................................................................................................................................................... [1]

The diagram shows a blast furnace for extracting iron.

(a) On the diagram above, write:
• the letter A to show where the air blast enters the furnace,
• the letter W to show where the waste gases exit the furnace. [2]
(b) Which one of the following is an ore of iron? Put a ring around the correct answer.
  calcite fluorit. hematite halite [1]
(c) In the furnace, the coke burns to form carbon dioxide. This reaction is exothermic.
(i) What is meant by the term _exothermic_?
.................................................................................................................... [1]
(ii) Describe a test for carbon dioxide.
  test ....................................................................................................
  result ............................................................................................... [2]
(d) In the blast furnace, carbon dioxide reacts with more coke to form carbon monoxide. The carbon monoxide reduces iron(III) oxide to iron.

$$\text{Fe}_{2}\text{O}_{3} + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_{2}$$
How does this equation show that iron(III) oxide is being reduced?
.................................................................................................................... [1]

The structure of ethanol is shown below.

(a) On the structure above, put a ring around the alcohol functional group. [1]

(b) Ethanol can be made by fermentation.
(i) Complete the word equation for fermentation.
...................... $\rightarrow$ ethanol + ...................... ...................... [2]
(ii) What type of catalysts are used in fermentation?
Put a ring around the correct answer.
acids carbonates enzymes metals [1]

(c) Ethanol can also be made by hydration.
Complete the symbol equation for this reaction.
...................... + $H_2O \rightarrow C_2H_5OH$ [1]

(d) The diagram below shows how the rate of fermentation changes with temperature.
Describe how the rate of fermentation changes with temperature.
.........................................................................................................................
.........................................................................................................................
......................................................................................................................... [2]

(e) The table shows some properties of different alcohols. [Table_1]

A student used chromatography to separate the dyes in the blue ink from a ball-point pen. She used the equipment shown in the diagrams below.

(a) Complete the diagram below to show how she set up the apparatus.

[3]
(b) Describe how chromatography could be used by the student to separate the dyes.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
[3]
(c) The student used water as a solvent. Suggest a different solvent that she could use.
..........................................................................................................................................................
[1]
(d) The diagram below shows the results of the chromatography using the blue ink, B, and several pure dyes, W, X, Y and Z.

(i) Which of the dyes, W, X, Y and Z, were in the blue ink?
..........................................................................................................................................................
[1]
(ii) How many dyes in the ink had been separated by this chromatography?
..........................................................................................................................................................
[1]
(e) The diagram shows the ball-point pen used in the experiment.

(i) The cap of the pen is made of poly(ethene). Describe the formation of poly(ethene) from ethene. In your answer, include the words:
• monomer,
• polymer.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
[2]
(ii) The tip of the pen is made from an alloy. What is meant by the term alloy?
..........................................................................................................................................................
..........................................................................................................................................................
[1]
(f) The table shows some properties of four alloys.
[Table_1]
(i) How does the strength of the steel and aluminium alloys vary with their thermal conductivity?
..........................................................................................................................................................
[1]
(ii) Which one of these alloys is the best one to use to make the body of an aircraft? Give two reasons for your answer.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
[3]

Zinc can be extracted from zinc sulfide ore in three steps.
(a) In the first step, zinc sulfide is heated in air to produce zinc oxide.
(i) Complete the symbol equation for this reaction.
$$2ZnS + ....O_2 \rightarrow 2ZnO + .....SO_2$$ [2]
(ii) The product sulfur dioxide, $SO_2$, is harmful to the environment. Explain why it is harmful to the environment and state one effect it has on buildings.
..........................................................................................................
.......................................................................................................... [2]
(b) In the second step, zinc oxide reacts with sulfuric acid to form zinc sulfate.
zinc oxide + sulfuric acid $\rightarrow$ zinc sulfate + water
Zinc sulfate is soluble in water. Some insoluble impurities in the zinc oxide do not react with the sulfuric acid. Suggest how these insoluble impurities are removed from the zinc sulfate solution.
.......................................................................................................... [1]
(c) In the third step, zinc is extracted from zinc sulfate by electrolysis using the cell shown below.

(i) Which word best describes the aluminium rod? Put a ring around the correct answer.
anion anode cathode cation electrolyte product [1]
(ii) Suggest which statement about this electrolysis is completely correct. Tick one box.
Zinc is formed at the positive electrode and hydrogen at the negative electrode. [ ]
Zinc is formed at the positive electrode and oxygen at the negative electrode. [ ]
Zinc is formed at the negative electrode and hydrogen at the positive electrode. [ ]
Zinc is formed at the negative electrode and oxygen at the positive electrode. [1]