Cambridge IGCSE Chemistry - 0620 - Core Paper 3 2009 Winter Zone 1

(a) Which two elements in the list are in the same Group of the Periodic Table? ............................................................. and ............................................................ bromine carbon fluorine krypton nitrogen oxygen

(b) Which element in the list has the highest proton number? ................................................................................................................................................

(c) Which two of these elements make up most of the air? ................................................................. and ..............................................................

(d) Bromine and fluorine form a compound with the formula $\text{BrF}_5$. Calculate the relative molecular mass of $\text{BrF}_5$.

(e) The diagram shows the structure of some compounds containing oxygen. A B C D (i) What type of oxide is compound C? ................................................................................................................................................ [1] (ii) Compound A is an atmospheric pollutant. Describe the source of compound A and state its effect on the environment. Source ......................................................................................................................................... Effect on the environment ........................................................................................................... ....................................................................................................................................... [2] (iii) In the presence of air, compound D reacts with water to form nitric acid. A student used the apparatus below to add an aqueous solution of nitric acid to an aqueous solution of potassium hydroxide. He added the acid until it was in excess. Describe how the pH of the solution in the flask changes as the nitric acid is added until the acid is in excess. ..................................................................................................................................................................... ..................................................................................................................................................................... ..................................................................................................................................................................... [3] (iv) Describe how you can measure this pH change. ............................................................................................................................................... [1] (v) The equation for the reaction is $\text{KOH} + \text{HNO}_3 \rightarrow \text{KNO}_3 + \text{H}_2\text{O}$ State the name of the salt formed in this reaction. ............................................................................................................................................... [1]

(a) Link the terms in the boxes on the left with the definitions on the right. The first one has been done for you.


(b) Which \textbf{two} of the following are mixtures? Tick two boxes.

air □
graphite □
sodium chloride □
steel □

(c) (i) Draw a labelled diagram to show the atomic structure of an atom of helium. In your diagram include the structure of the nucleus.

(ii) State a use for helium.
\text{.................................................................................................................................}
(iii) Which one of these statements about helium is correct?
helium is in Period 2 of the Periodic Table □
helium is a liquid at room temperature □
helium is unreactive □
helium has an incomplete outer shell of electrons □

(a) Draw the structure of ethanol showing all atoms and bonds.
[1]

(b) The energy released by the burning ethanol raises the temperature of the water in the copper calorimeter.
(i) Which one of these words best describes the energy change when ethanol burns? Put a ring around the correct answer.

electrolytic electronic endothermic exothermic
[1]

(ii) When 4.6 g of ethanol is burnt, 5.4 g of water is formed.
Calculate the mass of water formed when 13.8 g of ethanol is burnt.
[1]

(iii) Complete the equation for the combustion of ethanol.
$C_2H_5OH + 3O_2 \rightarrow ............ CO_2 + ............ H_2O$
[1]

(c) The calorimeter is made of copper. Copper is a transition metal.
State two properties which distinguish transition metals from Group I metals.

..........................................................................................................................
.........................................................................................................................
[2]

(d) When copper is left exposed to the air for some time, a coating of copper carbonate forms on its surface. The equation shows how copper carbonate reacts with hydrochloric acid.

$CuCO_3(s) + 2HCl(aq) \rightarrow CuCl_2(aq) + CO_2(g) + H_2O(l)$

(i) Describe two observations that can be made as this reaction happens.
1. .................................................................................................................................
2. .................................................................................................................................
[2]

(ii) State the meaning of the symbol (aq).
.................................................................................................................................
[1]

(e) The calorimeter lid is made of poly(ethene).
Complete these sentences about poly(ethene) using words from the list.

acids addition condensation ethane ethene monomers polymer

Poly(ethene) is a .......................... formed by the .......................... of ethene molecules.
In this reaction the ethene molecules can be described as ................................................
[3]

(a) State two physical properties of caesium.
...............................................................................................................................................
...............................................................................................................................................

(b) State the number of electrons in the outer shell of a caesium atom.
...............................................................................................................................................

(c) An isotope of caesium has a mass number of 133.
(i) What do you understand by the term isotope?
...............................................................................................................................................
(ii) Calculate the number of neutrons in this isotope of caesium.
...............................................................................................................................................

(d) Complete the following table to estimate the boiling point of caesium and predict the reactivity of caesium with water.

On the formula above, draw a circle around the bonds which make limonene an unsaturated compound.


Write the molecular formula for a molecule of limonene.
........................................................................................................................... ..............................................

Describe the colour change which occurs when excess limonene is added to a few drops of bromine water.
........................................................................................................................... ..............................................

Limonene can be extracted from lemon peel by steam distillation.

(i) State the name of the pieces of apparatus labelled $A$, $B$ and $C$.
...................................................................................................................
A ...................................................................................................................
B ...................................................................................................................
C ...................................................................................................................


(ii) At point $X$ on the diagram, the water is in the form of steam. Describe the arrangement and the movement of the particles in steam.
arrangement ...............................................................................................................
movement ................................................................................................................

When limonene undergoes incomplete combustion, carbon monoxide is formed.
(i) What do you understand by the term \textit{incomplete combustion}?
...............................................................................................................

(ii) State an adverse effect of carbon monoxide on health.
............................................................................................................

The structures of some compounds found in plants are shown below.
(i) Which one of these compounds is a carboxylic acid? .......................

(ii) Which one of these compounds is produced by the fermentation of glucose? .......................

(iii) Which one of these compounds is a hydrocarbon? .......................

Aluminium is extracted by the electrolysis of aluminium oxide.
[Image_1: Diagram of electrolysis process]
(a) Hydrated aluminium oxide is heated to produce pure aluminium oxide.
$$\text{Al}_2\text{O}_3·3\text{H}_2\text{O} \rightarrow \text{Al}_2\text{O}_3 + 3\text{H}_2\text{O}$$
What type of reaction is this?
Put a ring around the correct answer.
decompositon neutralisation oxidation reduction [1]
(b) Explain why the electrolyte must be molten for electrolysis to occur.
........................................................................ [1]
(c) What is the purpose of the cryolite?
.......................................................................... [1]
(d) Which letter in the diagram, A, B, C or D, represents the cathode?
....................................................................... [1]
(e) State the name of the products formed at the anode and cathode during this electrolysis.
anode .....................................................................
cathode ................................................................. [2]
(f) Why do the anodes have to be renewed periodically?
........................................................................ [2]
(g) Complete the equation for the formation of aluminium from aluminium ions.
$$\text{Al}^{3+} + ........ \text{e}^- \rightarrow \text{Al}$$ [1]
(h) State one use of aluminium.
........................................................................ [1]

The diagram shows an experiment to investigate the rusting of some iron nails.

(a) For each tube A, B and C predict whether the nails will rust. In each case give a reason.
tube A: does the nail rust? ............................................................................................
reason ...........................................................................................................................
tube B: does the nail rust? ............................................................................................
reason ...........................................................................................................................
tube C: does the nail rust? ............................................................................................
reason ...........................................................................................................................

(b) Iron from the blast furnace contains impurities such as carbon, phosphorus, silicon and sulfur.
Describe how the level of these impurities is decreased when steel is made from impure iron.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................

(c) State a use for stainless steel.
.....................................................................................................................................................

(d) Pure iron can be prepared by the reduction of iron(II) oxide, FeO.
FeO + H_2 \rightarrow Fe + H_2O
Explain how this equation shows that the iron(II) oxide has been reduced.
....................................................................................................................................................
....................................................................................................................................................

(e) Iron(II) oxide reacts with acids.
FeO + 2HCl \rightarrow FeCl_2 + H_2O
Write a word equation for this reaction.
....................................................................................................................................................