Cambridge IGCSE Chemistry - 0620 - Core Paper 3 2022 Summer Zone 1

(a) A list of symbols and formulae is shown.

CaO
CH₄
C₂H₄
C₂H₆
Cl⁻
Cu²⁺
H₂
He
K⁺
N₂
Na⁺
SO₂

Answer the following questions using these symbols or formulae.
Each symbol or formula may be used once, more than once or not at all.

State which symbol or formula represents:

(i) a compound produced by the thermal decomposition of calcium carbonate
................................................................................................................. [1]

(ii) a positive ion that gives a blue-green colour in a flame test
................................................................................................................. [1]

(iii) an element used as a fuel
................................................................................................................. [1]

(iv) the monomer used to produce poly(ethene)
................................................................................................................. [1]

(v) an ion formed when an atom gains an electron.
................................................................................................................. [1]

(b) Complete the table to show the relative charges of a proton, a neutron and an electron.

\[ \begin{array}{|c|c|}\hline \text{type of particle} & \text{relative charge} \\ \hline \text{proton} & +1 \\ \hline \text{neutron} & \\ \hline \text{electron} & \\ \hline \end{array} \]

[2]

(c) Choose the two correct statements about nitrogen.
Tick (✓) \text{two boxes}.

☐ Nitrogen molecules are monoatomic.
☐ All nitrogen atoms have seven protons.
☐ Nitrogen atoms cannot be split into simpler substances by chemical means.
☐ All nitrogen atoms have 14 neutrons.
☐ Nitrogen is 21% of clean, dry air.

[2]

The table shows the masses of some ions in a 1000 $\text{cm}^3$ sample of toothpaste.

[Table_1]

(a) Answer these questions using only the information in the table.

(i) State which negative ion has the lowest mass in 1000 $\text{cm}^3$ of toothpaste.

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

(ii) Name the compound that contains $\text{NH}_4^+$ and $\text{Cl}^-$ ions.

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

(iii) Calculate the mass of phosphate ions in 250 $\text{cm}^3$ of toothpaste.

mass = ..................... g [1]

(b) Describe a test for sulfate ions.

test ..............................................................
observations .............................................................. [2]

(c) Toothpaste also contains cinnamal.
The structure of cinnamal is shown.

Deduce the formula of cinnamal to show the number of atoms of carbon, hydrogen and oxygen.

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

(d) Cinnamal can be oxidised to a carboxylic acid.

(i) Draw the structure of a carboxylic acid functional group to show all of the atoms and all of the bonds.

[1]

(ii) Ethanoic acid is a carboxylic acid.
Ethanoic acid reacts like a typical acid.

Complete the word equation for the reaction of ethanoic acid with sodium carbonate.

ethanoic acid + sodium carbonate → sodium ethanoate + .............................................................. + .............................................................. [2]

This question is about halogens and halogen compounds.
(a) Deduce the number of electrons, neutrons and protons in one atom of the isotope of chlorine shown.
$$ \begin{align} ^{37}_{17}Cl \end{align} $$
number of electrons ...................................................................................................................
number of neutrons ...................................................................................................................
number of protons ..................................................................................................................... [3]
(b) State why chlorine is used in water treatment.
................................................................................................................................. [1]
(c) Aqueous chlorine reacts with aqueous potassium iodide.
(i) Complete the chemical equation for this reaction.
$$ Cl_2 + .....KI \rightarrow .....KCl + I_2 $$ [2]
(ii) Explain in terms of the reactivity of the halogens why aqueous iodine does not react with aqueous potassium chloride.
.................................................................................................................................
................................................................................................................................. [1]
(d) The table shows some properties of four halogens.

This question is about acids and bases.

(a) Describe the colour of methyl orange in acidic and alkaline solutions.
in acidic solution ............................................................................................................................
in alkaline solution ......................................................................................................................... [2]

(b) Complete the word equation for the reaction of hydrochloric acid with calcium oxide.



hydrochloric acid + calcium oxide \(\rightarrow\) ............................ + ............................
................................................................................. [2]

(c) Calcium oxide is lime.
Give \text{one} use of lime.
....................................................................................................................................... [1]

(d) The reaction of hydrochloric acid with calcium oxide is exothermic.

(i) State the meaning of the term \textit{exothermic}.
....................................................................................................................................... [1]

(ii) The energy level diagram for the reaction of hydrochloric acid with calcium oxide is shown.



Explain how the energy level diagram shows that this reaction is exothermic.
.......................................................................................................................................
....................................................................................................................................... [1]

This question is about Group IV elements and their compounds.
(a) The changes of state of lead are shown.
[Image_1: Solid lead - melting - Liquid lead - condensing - Lead gas with arrows indicating changes A and B]
Name the changes of state represented by A and B.
A .........................................................................................................................
B ......................................................................................................................... [2]
(b) Use the kinetic particle model to describe the differences between liquid lead and lead gas in terms of:
● the separation of the particles ........................................................................... ................................................................................................................................. .................................................................................................................................
● the motion of the particles. ................................................................................. ................................................................................................................................. ................................................................................................................................. [4]
(c) Lead is extracted from lead(II) oxide by heating with carbon.
PbO + C → Pb + CO
Describe how this equation shows that lead(II) oxide is reduced.
..................................................................................................................................
.................................................................................................................................. [1]
(d) Lead is a pollutant of the air.
(i) State one source of lead in the air.
................................................................................................................................. [1]
(ii) State one adverse effect of lead on health.
................................................................................................................................. [1]
(e) Diamond is a form of carbon.
The structure of diamond is shown.
[Image_2: Structure of diamond]
(i) Choose the word which best describes the structure of diamond.
Draw a circle around your chosen answer.
giant ionic metallic simple [1]
(ii) Name the type of bonding in diamond.
................................................................................................................................. [1]
(iii) Give one use of diamond.
................................................................................................................................. [1]
(iv) Deduce the electronic structure of carbon.
Use the Periodic Table to help you.
................................................................................................................................. [1]

(a) The structures of four organic compounds, C, D, E and F, are shown.


Answer the following questions about these compounds.
Each compound may be used once, more than once or not at all.

State which compound, C, D, E or F:

(i) decolourises aqueous bromine \text{.....................} \quad [1]

(ii) is an alcohol \text{.....................} \quad [1]

(iii) is unsaturated \text{.....................} \quad [1]

(iv) is in the same homologous series as ethane. \text{.....................} \quad [1]

(b) Petroleum is a mixture of hydrocarbons which can be separated into fractions with different boiling points.

Name the method used to separate these fractions.
\text{.....................} \quad [1]

(c) Complete the table to show the name and uses of some petroleum fractions.

[Table_1]

(d) Some hydrocarbons are formed by the process of cracking.

(i) State the meaning of the term \textit{cracking}.
\text{.....................} \quad [2]

(ii) Describe the conditions needed for cracking.
\text{.....................} \quad [2]

This question is about zinc and compounds of zinc.
(a) Zinc is a metal.
Give three physical properties of metals.
1 .....................................................................................................................
2 .....................................................................................................................
3 .....................................................................................................................
[3]

(b) Zinc reacts with phosphorus to form zinc phosphide, $Zn_3P_2$.
Complete the equation for this reaction.
.....Zn + .....P $\rightarrow$ $Zn_3P_2$ [2]

(c) Molten zinc chloride is electrolysed.
The incomplete apparatus is shown.


(i) Complete the diagram by:
• completing the circuit to show the wires and power pack
• labelling the anode.
[2]

(ii) Name the products formed at each electrode.
positive electrode ..........................................................................
negative electrode ..........................................................................
[2]

(d) Zinc chloride reacts with water as shown. The solution formed is acidic.
$$ZnCl_2 + 2H_2O \rightleftharpoons Zn(OH)_2 + 2HCl$$
(i) State the meaning of the symbol $\rightleftharpoons$.
.......................................................................................................... [1]

(ii) Choose the pH value which is acidic.
Draw a circle around your chosen answer.
pH 3   pH 7   pH 9   pH 14 [1]

(e) A compound of zinc has the formula $ZnC_4H_{10}$.
Complete the table to calculate the relative molecular mass of $ZnC_4H_{10}$.
[Table_1: atom, number of atoms, relative atomic mass]
zinc, 1, 65, $1 \times 65 = 65$
carbon, 4, 12, ................................
hydrogen, 10, 1, ................................
relative molecular mass = ................................
[2]

A student investigates the reaction of large pieces of copper(II) carbonate with dilute hydrochloric acid. The hydrochloric acid is in excess.
$$\text{CuCO}_3 + 2\text{HCl} \rightarrow \text{CuCl}_2 + \text{CO}_2 + \text{H}_2\text{O}$$
The rate of reaction is found by measuring the mass of the reaction mixture as time increases.
The results are shown on the graph.

(a) Deduce the mass of the reaction mixture at 30 s.
mass = .......................... g [1]

(b) The experiment is repeated using smaller pieces of copper(II) carbonate.

All other conditions stay the same.

Draw a line on the grid to show how the mass of the reaction mixture changes as time increases. [2]

(c) Describe the effect each of the following has on the rate of reaction of copper(II) carbonate with dilute hydrochloric acid.

All other conditions stay the same.

• The reaction is carried out in the presence of a catalyst.
..................................................................................
• The reaction is carried out using a lower concentration of hydrochloric acid.
.................................................................................. [2]

(d) When 0.2 g of copper(II) carbonate is used, 38 cm³ of carbon dioxide gas is produced.

Calculate the volume of carbon dioxide gas produced when 0.50 g of copper(II) carbonate is used.

volume of carbon dioxide gas = .......................... cm³ [1]