Cambridge IGCSE Chemistry - 0620 - Core Paper 3 2013 Winter Zone 1

(a) Choose from the list of elements below to answer the following questions.
calcium
helium
iodine
nickel
nitrogen
sodium
sulfur

Each element can be used once, more than once or not at all.

Which element:

(i) is an element present in most fertilisers, ........................................................... [1]
(ii) is in Group VI of the Periodic Table, ........................................................... [1]
(iii) is in Period 5 of the Periodic Table, ........................................................... [1]
(iv) has a single electron shell containing two electrons, ................................ [1]
(v) is a transition element, .................................................................................. [1]
(vi) forms ions with a single negative charge? ................................................ [1]

(b) What is the meaning of the term \textit{element}?
..................................................................................................................................................
.................................................................................................................................................. [1]

(c) Many of the elements in the Periodic Table have metallic properties.
Describe \textbf{three} physical properties which are typical of most metals.
1. ..................................................................................................................................................
2. ..................................................................................................................................................
3. .................................................................................................................................................. [3]

Hydrogen chloride is an acidic gas.
(a) (i) Complete the dot and cross diagram to show the electronic structure of hydrogen chloride.

(a) (ii) Is hydrogen chloride a covalent or an ionic compound? Give a reason for your answer.
..........................................................................................................................................

(b) Hydrogen chloride reacts with water to form hydrochloric acid. Which one of the following is the most likely pH of hydrochloric acid? Put a ring around the correct answer.
pH2 pH7 pH9 pH14

(c) Hydrochloric acid reacts with both metal oxides and carbonates.
(i) Complete the word equation for the reaction of hydrochloric acid with calcium carbonate.
hydrochloric acid + calcium carbonate $\rightarrow$ .................... + .................... + ....................

(c) (ii) Complete the symbol equation for the reaction of magnesium oxide with hydrochloric acid. Name the salt which is formed.
MgO + ......HCl $\rightarrow$ MgCl$_2$ + H$_2$O
name of salt ..................................................................................................

(d) A student reacted magnesium with hydrochloric acid to find out how concentration affects the rate of reaction. The magnesium was in excess. He measured the volume of hydrogen produced at various time intervals. The graph shows his results.
(i) At what time had the reaction just finished?
..........................................................................................................................................

(d) (ii) What volume of hydrogen gas is given off during the first 50 seconds of the reaction?
volume of hydrogen ................ cm$^3$

(d) (iii) The student repeated the experiment. State two factors, apart from the concentration of hydrochloric acid, that should be kept constant when repeating the experiment.
1. ...........................................................................................................
2. ...........................................................................................................

(a) Complete the following sentences about organic compounds and homologous series. Use words from the list below.
carbon chlorine different elements functional hydrocarbon hydrogen oxide similar sulfur
Organic compounds usually contain atoms of ........................... and ........................... .
Each homologous series contains compounds with ........................... chemical properties due to the presence of the same ........................... group. [4]

(b) Ethanol belongs to the alcohol homologous series.
(i) Draw the structure of ethanol, showing all atoms and bonds. [2]
(ii) State the name of the two compounds formed when ethanol burns in excess air.
............................................ and ............................................... [2]

(c) Salicylic acid is used to make aspirin.
The structure of salicylic acid is shown below.

(i) On this structure, put a ring around the carboxylic acid functional group. [1]
(ii) How many carbon atoms are there in one molecule of salicylic acid?
................................................................................................................ [1]
(iii) When making drugs and medicines, it is important that the chemicals used are pure. State one other area of everyday life where purity is important.
............................................................................................................... [1]

The structures of diamond and graphite are shown below.
(a) Describe the similarities and differences between these structures.
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................ [4]
(b) Graphite burns in excess air to form carbon dioxide. Describe a test for carbon dioxide.
test ...............................................................................................................................
result .............................................................................................................................. [2]
(c) When graphite is burnt in a limited supply of air, carbon monoxide is formed. State one adverse effect of carbon monoxide on health.
.............................................................................................................................. [1]
(d) In the blast furnace for the production of iron, carbon monoxide reduces iron(III) oxide.
$Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2$
How does this equation show that carbon monoxide is acting as a reducing agent?
.............................................................................................................................. [1]
(e) Iron(III) oxide and coke (carbon) are raw materials used in the production of iron. State the names of two other raw materials used in the blast furnace for the production of iron.
1. ..............................................................................................................................
2. .............................................................................................................................. [2]

Many plants contain coloured pigments.
A student crushes some plant leaves in alcohol to extract the pigments.
She then separates the pigments using the apparatus shown below.

(a) Write the correct labels in the boxes in the diagram above. [2]
(b) Draw an X on the diagram above to show where a drop of the pigment solution is placed at the start of the experiment. [1]
(c) After leaving the apparatus for half an hour, the pigments separated from each other.
State the name given to this method of separating pigments.
....................................................................................................................... [1]
(d) Some plants can absorb nickel from the ground. The nickel can then be extracted from the plants and purified by electrolysis.

(i) Which one of the following is the most suitable electrolyte for this electrolysis.
Tick one box.
aqueous copper(II) sulfate □
aqueous nickel(II) sulfate □
solid nickel(II) sulfate □
water □ [1]
(ii) Which one of the following elements is most likely to be formed at the negative electrode during this electrolysis?
Put a ring around the correct answer.
chlorine nickel sulfur oxygen [1]
(iii) The positive electrode is called the anode.
State the name of the negative electrode.
....................................................................................................................... [1]

(e) Electroplating is used to put a thin layer of one metal on top of another by electrolysis.
Give two reasons for electroplating metals.
1. .......................................................................................................................
2. ....................................................................................................................... [2]

(f) (i) Hydrated nickel(II) chloride is green in colour.
When hydrated nickel(II) chloride is heated gently, it changes colour from green to white.
Complete the symbol equation for this reaction.
$$\text{NiCl}_2\cdot 6\text{H}_2\text{O(s)} \rightleftharpoons \text{NiCl}_2(\text{s}) + \text{..................}$$
hydrated nickel(II) chloride [1]
(ii) What does the sign $\rightleftharpoons$ mean?
....................................................................................................................... [1]
(iii) How can you obtain a sample of green nickel(II) chloride starting with white nickel(II) chloride?
....................................................................................................................... [1]

The diagram shows a kettle of boiling water.

As the water vapour cools it turns back to water droplets.
(a) Describe this change of state in terms of the kinetic particle theory.
In your answer, include
• the difference in the closeness of the water molecules as the water vapour changes to water,
• the difference in the motion of the water molecules as the water vapour changes to water.
............
............
............
............
............ [4]
(b) Water is a common solvent in the laboratory.
(i) What is meant by the term solvent?
............ [1]
(ii) State the name of the solvent whose formula is $C_2H_5OH$.
............ [1]
(c) When ammonium chloride dissolves in water the temperature of the solution falls.
State the name of the energy change which results in the temperature falling.
............ [1]

(d) Which one of the following conducts electricity. Tick one box.
[ ] aqueous ammonium chloride
[ ] solid ammonium chloride
[ ] ammonia gas
[ ] chlorine gas
[1]
(e) (i) Complete the symbol equation for the reaction of lithium with water to form lithium hydroxide and hydrogen.
$$ 2Li + .....H_2O \to 2.......... + H_2 $$ [2]
(ii) When 14 g of lithium react with water, 4 g of hydrogen are formed.
Calculate the mass of hydrogen formed when 70 g of lithium react with water.
............ [1]

The table shows some properties of seven different substances.

[Table_1]

(a) Use the information in this table to answer the following questions.

(i) Which substance is the best conductor of heat?
......................................................................................................... [1]

(ii) Suggest why copper is preferred to iron for electrical wiring in houses.
......................................................................................................... [1]

(iii) What property of ceramic makes it a good electrical insulator?
......................................................................................................... [1]

(iv) Which pure metal in the table conducts electricity least well?
......................................................................................................... [1]

(v) Suggest why steel rather than iron is used in making machinery.
......................................................................................................... [1]

(vi) Which metal in the table is the most dense?
......................................................................................................... [1]

(b) A solution of a metal salt reacts with aqueous sodium hydroxide to form a white precipitate. The white precipitate is soluble in excess aqueous sodium hydroxide.

(i) Which one of the following ions is most likely to be present in the salt? Put a ring around the correct answer.
calcium copper(II) iron(II) zinc [1]

(ii) State the name of the white precipitate.
......................................................................................................... [1]

(c) Copper(II) chloride can be made by the action of hydrochloric acid on copper(II) oxide. Put the statements, A, B, C and D, about this preparation in the correct order.
A Leave the saturated solution to crystallise.
B Filter the solution to remove excess copper(II) oxide.
C Add excess copper(II) oxide to hydrochloric acid and warm.
D Evaporate the filtrate to the crystallisation point.
......................................................................................................... [1]

(d) The structure of copper(II) chloride is shown below.



Write the simplest formula for copper(II) chloride.
......................................................................................................... [1]

(e) Suggest the product formed at each electrode when molten copper(II) chloride is electrolysed.
at the positive electrode ..........................................................................
at the negative electrode .......................................................................... [2]

(f) When copper(II) chloride is heated strongly, a gas is given off. The gas is green in colour and bleaches litmus paper. State the name of this gas.
......................................................................................................... [1]