4CH1/2C — June 2026 (Edexcel IGCSE Chemistry): Past Paper

This question is about polymerisation.

The box gives some names used in polymerisation. addition alkane alkene condensation dicarboxylic acid poly(chloroethene) water Complete the table by choosing the correct name from the box that matches each description. Description Name a monomer used to make an addition polymer a monomer used to make a condensation polymer a type of polymer that biodegrades a product of condensation polymerisation

Which structure shows the correct repeating unit for poly(propene)?

This is the displayed formula for butane‑1,4‑dioic acid.

Determine the molecular formula for butane‑1,4‑dioic acid.

Complete the chemical equation for the reaction between butane‑1,4‑dioic acid and sodium.

Butane‑1,4‑dioic acid can react to form this polyester. Draw a circle around the part of the polyester that comes from a butane‑1,4‑dioic acid molecule.

A titration can be used to prepare soluble salts.

Name a negative ion that always gives a salt that is soluble in water.

A student sets up this apparatus to do a titration. bung burette 250 cm³ beaker The student makes two mistakes when setting up their apparatus. Suggest two changes to the student’s set up that need to be made if the titration is to be done correctly. 1 2

The student plans this method for their titration. • add 25.0 cm³ of an alkali to the beaker • add an acid to the burette until the level reaches 0.00 cm³ • open the burette tap and add acid to the beaker until there is a colour change • record the final reading on the burette • repeat the method until concordant results have been obtained. Give three improvements to the student’s method. Do not refer to changes in apparatus in your answer. 1 2 3

Another student does a titration using the correct method. The table shows their results

Concordant results are those within 0.20 cm³ of each other. Add ticks (✓) to the table to show the concordant results.

Use the concordant results to calculate the mean volume of acid added. mean volume = cm³

Sodium hydroxide solution is used in titrations.

Explain whether sodium hydroxide solution is an acid, an alkali or a salt.

Solid sodium hydroxide is dissolved in excess water to make a solution. This process is exothermic, with 47 kJ of energy released per mole. Calculate the energy released, in kJ, when 0.55 kg of solid sodium hydroxide is dissolved in excess water. [for sodium hydroxide Mr = 40] energy released = kJ

This question is about electrolysis.

Compounds that only contain covalent bonds cannot be electrolysed.

Describe what is meant by the term covalent bond.

State why covalent compounds do not conduct electricity.

Lead(II) bromide is an ionic compound that can be electrolysed.

During electrolysis, the lead(II) bromide is at a temperature of 400 °C. Explain a suitable material for the electrodes.

The lead(II) ions in this electrolysis have a positive charge. Give the term used to refer to all positive ions.

Give the half‑equation for the reaction at the positive electrode.

Identify the particles that flow through the wires connecting the electrodes.

Sodium chloride can also be electrolysed.

The table gives the products at the positive electrode for the electrolysis of sodium chloride under different conditions. Complete the table by giving the missing information. Product at Condition Product at negative electrode positive electrode molten sodium chloride chlorine aqueous sodium chloride chlorine

Explain how chlorine gas forms at the positive electrode.

Molten sodium chloride is electrolysed to give 5000 mol of chlorine gas. Calculate the maximum volume, in dm³, of chlorine gas produced at rtp. [molar volume of chlorine at rtp = 24 000 cm³] maximum volume = dm³

Potassium chloride is a soluble salt with the formula KCl

A flame test is done on a sample of potassium chloride. State the colour of the flame.

Give a reason why adding blue litmus paper to a solution of potassium chloride is not a suitable test for chloride ions.

Give a suitable test for chloride ions.

A student is given a sample of solid potassium chloride. Describe a method that the student could use to make 250 cm³ of 0.500 mol/dm³ potassium chloride solution. Include suitable calculations and apparatus in your answer. [for potassium chloride Mr = 74.5]

Ethanoic acid reacts with ethanol to produce ethyl ethanoate and water. This reaction is reversible.

Complete the equation for the reaction between ethanoic acid and ethanol by adding the displayed formula of the missing reactant and the missing product. CH₃COOH + ⇌ + H₂O

Ethanoic acid and ethanol are mixed in a beaker. ethanoic acid and ethanol Give a reason why this reaction is unlikely to reach equilibrium.

The reaction between ethanoic acid and ethanol can be catalysed by sulfuric acid.

Explain how a catalyst works.

Describe the effect of adding a catalyst on the yield of ethyl ethanoate at equilibrium. Give a reason for your answer.

The reaction between ethanoic acid and ethanol is exothermic. Explain the effect that increasing the temperature would have on • yield of ethyl ethanoate at equilibrium • rate at which equilibrium is reached.

This question is about the solubility of potassium sulfate in water.

Give the formula for potassium sulfate. This method can be used to determine the solubility of potassium sulfate at different temperatures. • add a known mass of potassium sulfate to 25 cm³ of water in a boiling tube • warm the boiling tube until all the potassium sulfate has dissolved • cool the solution until crystals first appear, and record the temperature of the solution Repeat the method with different masses of potassium sulfate.

Give a suitable piece of equipment to measure the temperature of the solution.

State the independent variable in this method.

State why this method is not suitable for determining the solubility of barium sulfate.

The table shows the maximum mass of potassium sulfate that dissolves in 100 cm³ of water at different temperatures

Use data from the table to determine the mass of potassium sulfate dissolved in the boiling tube at 27.4 °C. mass = g

A 200 cm³ saturated solution of potassium sulfate is cooled from 55.6 °C to 27.4 °C. Determine the mass, in g, of solid potassium sulfate that would crystallise. mass = g