4CH1/2CR — June 2023 (Edexcel IGCSE Chemistry): Past Paper

The table lists three subatomic particles. Complete the table by giving the missing information. Subatomic particle Relative mass Relative charge proton +1 neutron electron 0.0005

The diagram shows the position of some elements in the Periodic Table. Be F P Xe Use the Periodic Table on page 2 to help you answer this question.

How are elements arranged in the Periodic Table?

Which statement is correct about the position of phosphorus, P, in the Periodic Table?

Explain which of the four elements in the diagram is least reactive.

The table gives some information about the halogens, fluorine, chlorine, bromine and iodine

Complete the table by giving the missing information.

Describe a test to show that a colourless liquid is an alkene.

A student is given an aqueous solution of chlorine and an aqueous solution of sodium iodide. The student mixes the two solutions. Explain the colour change that occurs.

The box gives the names of some metals. aluminium calcium gold magnesium silver zinc Use words from the box to answer these questions.

Identify the metal that burns with a bright white flame.

Explain which metal is most likely to be found in the Earth as an uncombined element.

Steel is an alloy of iron and carbon. The diagram shows how the particles are arranged in steel. iron atom carbon atom

State what is meant by the term alloy.

Explain why an alloy is less malleable than a pure metal.

The diagram shows a fractionating column used to separate crude oil into fractions. refinery gases gasoline kerosene diesel crude oil fuel oil bitumen

Give one use for refinery gases and one use for bitumen. refinery gases bitumen

Give a reason why refinery gases rise to the top of the column.

State what must happen to the crude oil before it is pumped into the column.

There is a low demand for some of the hydrocarbons obtained from crude oil. Catalytic cracking can be used to convert low‑demand hydrocarbons into more useful products.

Give the conditions needed for cracking.

The cracking of tetradecane is shown in the equation. C₁₄H₃₀ → 2C₃H₆ + C₈H₁₈ Explain why there is a high demand for both of the products.

This question is about the insoluble salt, lead(II) bromide. Lead(II) bromide can be made by a precipitation reaction. This is the equation for the reaction. Pb(NO₃)₂(aq) + 2KBr(aq) → PbBr₂(s) + 2KNO₃(aq)

Describe how solutions of lead nitrate and potassium bromide can be used to make a pure, dry sample of lead(II) bromide.

A solution containing 0.150 mol of lead(II) nitrate is reacted with an excess of potassium bromide solution. A mass of 49.6 g of pure, dry lead(II) bromide is produced. Show, by calculation, that the percentage yield of lead(II) bromide is 90.1%. [for PbBr₂ , Mr = 367]

A student investigates the change in electrical conductivity as dilute lead(II) nitrate solution is added to dilute potassium bromide solution. This is the student’s method. Step 1 add 50 cm³ of potassium bromide solution to a beaker Step 2 measure the electrical conductivity of the solution Step 3 add 10 cm³ of lead(II) nitrate solution to the beaker Step 4 stir the mixture Step 5 measure the electrical conductivity of the mixture Repeat steps 3, 4 and 5 until a total of 50 cm³ of lead(II) nitrate solution has been added. The table shows the student’s results. Total volume of lead(II) nitrate Electrical conductivity solution added in cm³ in arbitrary units 0 10.00 10 9.80 20 9.77 30 9.40 40 9.20 50 9.00

Plot the student’s results on the grid.

Draw a line of best fit, ignoring the anomalous result. 10.00 9.80 9.60 Electrical conductivity in arbitrary units 9.40 9.20 9.00 0 10 20 30 40 50 Total volume of lead(II) nitrate in cm

Explain the shape of the graph.

Suggest a mistake the student could have made to cause the anomalous result.

Further 10 cm³ volumes of lead(II) nitrate are added to the beaker so the lead(II) nitrate is in excess. Predict what will happen to the conductivity of the mixture when the lead(II) nitrate is in excess.

The diagram shows the electrolysis of molten lead(II) bromide, PbBr₂ + – A B molten lead(II) bromide crucible This is the ionic half‑equation for the formation of bromine at electrode A. 2Br − → Br 2 + 2e− Give a reason why this half‑equation shows oxidation.

Describe the forces of attraction in metallic bonding.

When a small piece of potassium is added to water, bubbles of hydrogen gas are observed.

Give the test for hydrogen gas.

Give two other observations that would be made. 1 2

Explain why lithium is less reactive than potassium. Refer to atomic structure in your answer.

This is the equation for the reaction between sodium and water. 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g) A mass of 0.750 g of sodium is reacted with an excess of water. Calculate the volume of hydrogen gas produced, in cm³, at room temperature. [molar volume of hydrogen at rtp = 24 000 cm³] [for Na, Ar = 23] Give your answer to three significant figures. volume of hydrogen = cm³

This is the equation for the reaction between sodium hydroxide and sulfuric acid. 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O A volume of 25.0 cm³ of sodium hydroxide solution is completely neutralised by 16.3 cm³ of 0.0500 mol / dm³ sulfuric acid. Calculate the concentration of the sodium hydroxide solution in mol / dm³. concentration = mol / dm³

Methanol is made by the reaction between hydrogen and carbon monoxide. This is the equation for the reaction. 2H₂(g) + CO(g) ⇌ CH₃OH(g) ΔH = −119 kJ / mol A mixture of hydrogen and carbon monoxide is left until dynamic equilibrium is reached.

Give two characteristics of a reaction at dynamic equilibrium. 1 2

Give a reason why adding a catalyst does not affect the yield of methanol.

The temperature of the reaction mixture is decreased at constant pressure. Explain the effect of this change on the yield of methanol.

The pressure of the reaction mixture is increased at constant temperature. Explain the effect of this change on the yield of methanol.

This equation shows the displayed formulae for the reactants and product. H H H + C O ⇌ H C O H H H H The table gives the bond energies for the bonds in the reactants and product. Bond energy Bond in kJ / mol H H 436 C O 1072 C H 414 C O 358 O H 463

Show that the molar enthalpy change, ΔH, for the reaction is −119 kJ / mol.

Explain why this reaction is exothermic.

The diagram shows the displayed formula of an ester that is made from methanol and a carboxylic acid

Draw a circle around the functional group of the ester.

Give the displayed formula of the carboxylic acid used to make this ester.