4CH1/1C — June 2024 (Edexcel IGCSE Chemistry): Past Paper

The box shows the names of some substances.

bromine · chlorine · diamond · ethene · iodine · lithium · methane · water

Complete the table by choosing a substance from the box that matches each description. Each substance may be used once, more than once or not at all. Description Substance a good conductor of electricity an element that is a liquid at room temperature a substance that can be used to form a polymer an element that forms a basic oxide a substance that has a giant covalent structure

Describe a test for chlorine.

This question is about the reactivities of metals.

The table shows the reactions of four metals, P, Q, R and S, with water and with dilute hydrochloric acid. The letters are not the symbols of the elements. Metal Reaction with water Reaction with dilute hydrochloric acid P no reaction no reaction Q very fast reaction (not done) R no reaction slow reaction S slow reaction fast reaction

Deduce the order of reactivity of the metals. most reactive least reactive

Give the letter of the metal that could be zinc.

Give a word equation for the reaction between aluminium and hydrochloric acid.

Give the name of a metal that could be P.

Give a reason why the reaction of Q with dilute hydrochloric acid is not done.

The diagram shows the apparatus used to demonstrate the reaction between aluminium and iron(III) oxide. magnesium fuse mixture of aluminium powder and iron(III) oxide powder When the magnesium fuse is lit, a very exothermic reaction occurs. This is the equation for the reaction. Fe₂O₃ + 2Al → 2Fe + Al₂O₃

State what is meant by the term exothermic.

State why aluminium displaces iron.

Explain why this reaction is a redox reaction.

The diagram represents an atom of element Z. Z is not the symbol of the element.

Give the number of the group to which element Z belongs.

Give the number of the period to which element Z belongs.

Give the formula of the compound that forms when Z reacts with fluorine.

One mole of Z contains 6.0 × 10²³ atoms. Calculate the number of electrons in one mole of atoms of element Z. Give your answer in standard form. number of electrons =

A sample of element Z contains three isotopes. The table shows the numbers of particles in the nucleus of each isotope and the percentage abundance of each isotope. Isotope Number of protons Number of neutrons Percentage abundance 1 12 12 79.0 2 12 13 10.0 3 12 14 11.0 Use the information in the table to calculate the relative atomic mass (Ar) of element Z. Give your answer to one decimal place. Ar =

Deduce the name of element Z.

Caffeine is a stimulant found in coffee, tea and some soft drinks.

The molecular formula of caffeine is C₈H₁₀N₄O₂

Determine the number of atoms in one molecule of caffeine.

Calculate the relative formula mass (Mr ) of caffeine. Mr =

Give the empirical formula for caffeine.

Ethanol can be obtained from a solution of caffeine in ethanol using this apparatus. water out X water in caffeine in ethanol heat

Give the name of the method of separation shown in the diagram.

Describe what happens to the ethanol vapour in apparatus X.

Calcium bromide is an ionic compound. The table shows the formulae and melting points of caffeine and calcium bromide. Name Formula Melting point in °C caffeine C₈H₁₀N₄O₂ 235 calcium bromide CaBr₂ 730 The relative formula mass of calcium bromide is similar to the relative formula mass of caffeine. Explain why calcium bromide has a much higher melting point than caffeine.

A student uses paper chromatography in an experiment to separate the dyes in four different felt tip pens, E, F, G and H. The diagram shows the appearance of the paper before and after the experiment

The chromatography paper is placed in a solvent. Explain why the spots on the baseline are placed above the level of the solvent.

Explain which two felt tip pens contain the same dye.

The student thought that both F and G contained only one dye. Explain why the student can only be certain about one of these dyes.

Calculate the Rf value for the dye in G. Show your working. Rf value =

This question is about some Group 1 elements and their compounds.

A teacher adds a small piece of sodium to a trough of water.

Give two observations that are made when sodium reacts with water. 1 2

After the reaction has stopped, the teacher adds a few drops of phenolphthalein to the solution in the trough. Explain the colour of the phenolphthalein after it is added to the solution.

A student does a flame test to see if a white solid contains lithium ions. They clean a platinum wire before using it for the flame test.

Explain why the student needs to clean the platinum wire.

What is the colour of the flame if the solid contains lithium ions?

Potassium aluminium sulfate can be used in baking. Anhydrous potassium aluminium sulfate has the formula KAl(SO₄)₂

Give the formula of each ion in potassium aluminium sulfate. potassium ion aluminium ion sulfate ion

Potassium aluminium sulfate is normally found as a hydrated salt, with the formula KAl(SO₄)₂.xH₂O When 23.7 g of the hydrated salt is heated to remove all the water, 12.9 g of the anhydrous salt is formed. Calculate the value of x. [for KAl(SO₄)₂ , Mr = 258 for H₂O , Mr = 18] x =

This question is about nitrogen and its compounds.

What is the approximate percentage by volume of nitrogen in the atmosphere?

Complete the dot-and-cross diagram for a molecule of nitrogen. Show outer electrons only. N N

Nitrogen dioxide produced in car engines reacts with water vapour and oxygen in the atmosphere to form nitric acid.

Give a chemical equation for this reaction.

Nitric acid forms acid rain. State one environmental effect of acid rain.

Ammonium carbonate contains nitrogen.

What is the formula of ammonium carbonate?

A technician finds an unlabelled bottle on a shelf that could be ammonium carbonate solution. Describe tests that the technician should do to confirm that the solution contains ammonium ions and carbonate ions.

This question is about hydrocarbons.

The molecular formula C₄H₈ represents all the isomers of an alkene.

Explain what is meant by the term isomers.

The displayed formula of one of the isomers of the alkene is shown. Draw displayed formulae for two other alkene isomers with the molecular formula C₄H₈ alkene isomer 1 alkene isomer 2

But-1-ene reacts with bromine to form a compound with molecular formula C₄H₈Br₂ What is the name given to this type of reaction?

The alkene C₃H₆ can be polymerised to form the polymer poly(propene).

Draw the repeat unit of poly(propene).

These are two methods for disposing of polymers such as poly(propene). method 1 burying them in landfill sites method 2 burning them to release heat energy State one environmental problem linked to each of these methods of disposal. method 1 method 2

Complete combustion of one mole of an alkane produces 396 g of carbon dioxide and 180 g of water. This is the equation for the reaction. alkane + xO₂ → yCO2 + zH₂O Calculate the values of x, y and z. [for CO₂ , Mr = 44 for H₂O , Mr = 18] x = y = z =

In a petrol engine, incomplete combustion occurs because there is a limited supply of oxygen.

Petrol contains octane, C₈H₁₈ Complete the equation for this reaction, including state symbols. C₈H₁₈(l) + O₂( ) → CO( ) + 3C( ) + H₂O( )

Explain one problem for humans caused by a product of this incomplete combustion.

A student uses this apparatus to investigate the rate of reaction between marble chips and dilute hydrochloric acid. cotton wool marble chips dilute hydrochloric acid g balance This is the equation for the reaction. CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

During the reaction the reading on the balance decreases because mass is lost from the flask.

State why mass is lost from the flask.

State the purpose of the cotton wool.

This is a graph of the student’s results

Explain the shape of the graph. You should assume that the marble chips are in excess.

On the grid, draw the curve you would expect to obtain if the student uses the same volume of hydrochloric acid but with half the concentration. Assume that all other conditions are kept the same.

The student repeats the experiment using the same mass of smaller marble chips. Explain, using particle collision theory, how using smaller marble chips would affect the rate of this reaction. Assume that all other conditions are kept the same as in the initial experiment.

A student investigates the reaction between magnesium and nitric acid. The student uses this method.

• add 40 cm³ of dilute nitric acid to a glass beaker
• record the temperature of the acid
• find the mass of a strip of magnesium ribbon
• add the magnesium ribbon to the nitric acid
• when all the magnesium has reacted, record the highest temperature reached

Complete the chemical equation for this reaction. Mg + 2HNO₃ → +

The thermometer shows the highest temperature reached. °C Complete the table by giving the temperatures to the nearest 0.1°C starting temperature of the acid in °C highest temperature reached in °C temperature rise in °C 16.4

Show that the heat energy change (Q ) for this reaction is about 2800 J. [for 1.0 cm³ of solution, mass = 1.0 g] [for the solution, c = 4.2 J/g/°C]

The mass of magnesium used by the student was 0.12 g. Calculate the value of the enthalpy change (ΔH ), in kJ/mol, for the magnesium reacting with nitric acid. Give your answer to two significant figures, including a sign in your answer. ΔH = kJ/mol

Explain why using a polystyrene cup, instead of a glass beaker, would give a more accurate result.