IGCSE Chemistry 0620 Paper 42, May/June 2023

is responsible for acid rain

has a giant covalent structure

is a reducing agent in the blast furnace

is the main constituent of bauxite

is the main impurity in iron ore

can be reduced by heating with copper.

State the name given to Group VII elements.

Explain why Group VII elements have similar chemical properties.

Complete Table 2.1 to show the colour and state at r.t.p. of some Group VII elements. Table 2.1

Bromine has two naturally occurring isotopes, ${}^{79}\mathrm{B}\mathrm{r}$ and ${}^{81}\mathrm{B}\mathrm{r}$. State the term given to the numbers 79 and 81 in these isotopes of bromine.

Complete Table 2.2 to show the number of protons, neutrons and electrons in the atom and ion of bromine shown. Table 2.2

Table 2.3 shows the relative abundances of the two naturally occurring isotopes of bromine. Table 2.3

Calculate the relative atomic mass of bromine to one decimal place. relative atomic mass = ..............................

Chlorine displaces bromine from aqueous potassium bromide but does not displace fluorine from aqueous sodium fluoride. Write the symbol equation for the reaction between chlorine and aqueous potassium bromide.

State why chlorine does not displace fluorine from aqueous sodium fluoride.

Aqueous silver nitrate is a colourless solution containing ${\mathrm{A}\mathrm{g}}^{+}(\mathrm{a}\mathrm{q})$ ions. Describe what is seen when aqueous silver nitrate is added to aqueous sodium chloride.

Write the ionic equation for the reaction between aqueous silver nitrate and aqueous sodium chloride. Include state symbols.

State the name of the process used to manufacture sulfuric acid.

Part of the manufacture of sulfuric acid involves converting sulfur dioxide to sulfur trioxide. Describe two methods by which sulfur dioxide is obtained.

The conversion of sulfur dioxide to sulfur trioxide is a reversible reaction which can reach equilibrium. $$2{\mathrm{S}\mathrm{O}}_2(\mathrm{g})+{\mathrm{O}}_2(\mathrm{g})\rightleftharpoons 2{\mathrm{S}\mathrm{O}}_3(\mathrm{g})$$ State two features of an equilibrium.

State the typical conditions and name the catalyst used in the conversion of sulfur dioxide to sulfur trioxide. temperature .......................................... ${}^{\circ }\mathrm{C}$ pressure ................................................ $\mathrm{k}\mathrm{P}\mathrm{a}$ catalyst .................................................

Complete Table 3.1 to show the effect, if any, when the following changes are applied to the conversion of sulfur dioxide to sulfur trioxide. $$2{\mathrm{S}\mathrm{O}}_2(\mathrm{g})+{\mathrm{O}}_2(\mathrm{g})\rightleftharpoons 2{\mathrm{S}\mathrm{O}}_3(\mathrm{g})$$ The forward reaction is exothermic. Only use the words increases, decreases or no change. Table 3.1

Explain in terms of collision theory why reducing the temperature decreases the rate of the forward reaction.

Sulfuric acid contains ${\mathrm{S}\mathrm{O}}_4^{2-}$ ions. The oxidation number of $\mathrm{O}$ atoms in ${\mathrm{S}\mathrm{O}}_4^{2-}$ ions is $-2$. Determine the oxidation number of $\mathrm{S}$ atoms in ${\mathrm{S}\mathrm{O}}_4^{2-}$ ions. Show your working. oxidation number = ..............................

State what is meant by the term base.

State the term given to a base which dissolves to form an aqueous solution.

State the colour of thymolphthalein in $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}(\mathrm{a}\mathrm{q})$.

Complete the word equation for the reaction of $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}(\mathrm{a}\mathrm{q})$ with ammonium chloride.

+

$\to$ ........................ + ........................ + ........................

Some metal oxides react with $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}(\mathrm{a}\mathrm{q})$. State the term given to metal oxides which react with bases such as $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}(\mathrm{a}\mathrm{q})$.

Name a metal oxide which reacts with $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}(\mathrm{a}\mathrm{q})$.

Ethanoic acid, ${\mathrm{C}\mathrm{H}}_3\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}$, is a weak acid. Complete the dot-and-cross diagram in Fig. 4.1 of a molecule of ethanoic acid.

Suggest the pH of dilute ethanoic acid.

Complete the symbol equation to show the dissociation of ethanoic acid. ${\mathrm{C}\mathrm{H}}_3\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}$ ....................................................................................................................

Write the ionic equation for the reaction when an acid neutralises a soluble base.

In a titration, $25.0{\mathrm{c}\mathrm{m}}^3$ of $0.0800{\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{/}\mathrm{d}\mathrm{m}}^3$ aqueous potassium hydroxide, $\mathrm{K}\mathrm{O}\mathrm{H}(\mathrm{a}\mathrm{q})$, is neutralised by $20.0{\mathrm{c}\mathrm{m}}^3$ of dilute sulfuric acid, ${\mathrm{H}}_2{\mathrm{S}\mathrm{O}}_4(\mathrm{a}\mathrm{q})$. $$2\mathrm{K}\mathrm{O}\mathrm{H}(\mathrm{a}\mathrm{q})+{\mathrm{H}}_2{\mathrm{S}\mathrm{O}}_4(\mathrm{a}\mathrm{q})\to {\mathrm{K}}_2{\mathrm{S}\mathrm{O}}_4(\mathrm{a}\mathrm{q})+2{\mathrm{H}}_2\mathrm{O}(\mathrm{l})$$ Calculate the concentration of ${\mathrm{H}}_2{\mathrm{S}\mathrm{O}}_4$, in ${\mathrm{g}\mathrm{/}\mathrm{d}\mathrm{m}}^3$ using the following steps. • Calculate the number of moles of $\mathrm{K}\mathrm{O}\mathrm{H}$ used. .............................. mol • Determine the number of moles of ${\mathrm{H}}_2{\mathrm{S}\mathrm{O}}_4$ which react with the $\mathrm{K}\mathrm{O}\mathrm{H}$. .............................. mol • Calculate the concentration of ${\mathrm{H}}_2{\mathrm{S}\mathrm{O}}_4$ in ${\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{/}\mathrm{d}\mathrm{m}}^3$. .............................. mol/dm${}^3$ • Calculate the concentration of ${\mathrm{H}}_2{\mathrm{S}\mathrm{O}}_4$ in ${\mathrm{g}\mathrm{/}\mathrm{d}\mathrm{m}}^3$. .............................. g/dm${}^3$

When a molecule of propane, ${\mathrm{C}}_3{\mathrm{H}}_8$, reacts with chlorine in the presence of ultraviolet light, one atom of hydrogen is replaced by one atom of chlorine. State the term given to reactions in which one atom in an alkane is replaced by another atom.

State the purpose of ultraviolet light in this reaction.

State the term given to any reaction which requires ultraviolet light.

Write the symbol equation for the reaction between propane and chlorine.

A molecule of propene, ${\mathrm{C}}_3{\mathrm{H}}_6$, is unsaturated and will react with chlorine at room temperature. State why propene is an unsaturated molecule.

Give the structural formula of the product of this reaction.

Propene undergoes addition reactions with steam. There are two possible products, A and B. Draw the displayed formula and name each product. displayed formula of product A name of product A ..................................................................................................................... displayed formula of product B name of product B .....................................................................................................................

Name the ester formed when butanoic acid, ${\mathrm{C}\mathrm{H}}_3{\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_2\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}$, reacts with ethanol, ${\mathrm{C}\mathrm{H}}_3{\mathrm{C}\mathrm{H}}_2\mathrm{O}\mathrm{H}$.

Identify the other product formed in this reaction.

Deduce the empirical formula of the ester formed.

PET is a polyester. Part of the structure of PET is shown in Fig. 6.1. Circle one repeat unit of this polymer.

Draw the structures of the monomers which make up PET. Draw the functional groups using displayed formulae.

State the type of polymerisation used in making PET.