4CH1/1C — June 2021 (Edexcel IGCSE Chemistry): Past Paper

The box shows the names of some substances.

bromine · carbon dioxide · copper · iodine · methane · nitrogen · sulfur dioxide · water

Complete the table by choosing substances from the box that match the description. Each substance may be used once, more than once or not at all. Description Substance a good conductor of electricity an element that has a basic oxide a substance used as a fuel a major cause of acid rain a non‑metallic element that is a solid at room temperature

Describe a test for carbon dioxide.

Table 1 gives some information about three subatomic particles.

Complete Table 1 by giving the missing information. Subatomic particle Relative mass Relative charge electron 0.0005 proton +1 neutron 1 Table 1

Give the name of the part of the atom containing protons and neutrons.

Table 2 shows the numbers of protons, neutrons and electrons in the species U, V, W, X, Y and Z. Species Number of protons Number of neutrons Number of electrons U 8 10 8 V 9 10 10 W 11 12 10 X 11 12 11 Y 12 12 12 Z 12 13 12 Table 2 Use the information in Table 2 to answer these questions. Each species may be used once, more than once or not at all.

Give the letter of the species that has six electrons in its outer shell.

Give the mass number of Z.

Give the letter of the species that is a positive ion.

Give the letters of the two species that are isotopes of the same element.

A sample of neon contains two isotopes, 20Ne and 22Ne The relative abundances of the two isotopes in the sample are 20 22 Ne 91.2% Ne 8.80% Calculate the relative atomic mass of this sample of neon. Give your answer to one decimal place. relative atomic mass =

Some sugar is added to cold water in a beaker. After some time, all the sugar dissolves and spreads throughout the water.

Name the process that occurs which causes the sugar to spread throughout the water.

State two ways to make the sugar dissolve more quickly. 1 2

Pure water can be obtained from the sugar solution using this apparatus. water out X water in heat

Name the process used to obtain pure water from the sugar solution.

Explain the purpose of the piece of apparatus labelled X.

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

Describe how the student should complete the experiment after putting a spot of each food colouring on the paper.

Deduce the number of dyes in food colouring H.

Suggest why food colouring F does not move during the experiment.

Explain which two food colourings contain the dye that is likely to be the most soluble in the solvent.

Determine which food colouring contains a dye with Rf value closest to 0.67 Show your working.

This question is about alkanes and alkenes.

Complete the boxes by giving the missing information about the alkane with the molecular formula C₂H₆ molecular formula C₂H₆ name empirical formula displayed formula

Complete the chemical equation for the complete combustion of the alkane C₂H₆ C₂H₆ + O₂ → CO₂ + H₂O

Incomplete combustion occurs when the air supply is limited. Give the names of two products of incomplete combustion. 1 2

An alkene with molecular formula C₄H₈ reacts with bromine to form a compound with molecular formula C₄H₈Br₂

What is the name of this type of reaction?

Draw displayed formulae for two different alkenes with the molecular formula C₄H₈ alkene 1 alkene 2

State the term used for compounds with the same molecular formula but different structural formulae.

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

Complete the equation for this polymerisation reaction.

Two ways of disposing of polymers such as poly(propene) are • burying them in landfill sites • burning them to release heat energy Discuss the environmental problems caused by these two methods of disposal.

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

A teacher adds a small piece of lithium to water in a trough.

Give three observations that are made when lithium reacts with water. 1 2 3

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

Write a chemical equation for the reaction of lithium with water. .

A student does a flame test to see if a white solid contains sodium ions. She cleans a platinum wire before using it for the flame test.

Explain why the student needs to clean the platinum wire.

Which of these is the colour of the flame if the solid contains sodium ions?

Potassium sulfate (K₂SO₄) is an ionic compound.

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

The melting point of potassium sulfate is 1069 °C. Explain why potassium sulfate has a high melting point. Refer to structure and bonding in your answer.

A student investigates the reaction between magnesium and hydrochloric acid. He uses this method. Step 1 add 25 cm³ of dilute hydrochloric acid to a polystyrene cup Step 2 record the temperature of the acid Step 3 find the mass of a 10 cm strip of magnesium ribbon Step 4 add the magnesium ribbon to the hydrochloric acid Step 5 when all the magnesium has reacted, record the highest temperature reached

Complete the word equation for the reaction. magnesium + hydrochloric acid → +

The thermometer shows the temperature of the acid at the start of the experiment. °C 25

Complete the table by giving the temperatures to the nearest 0.1 °C. temperature of the acid at the start in °C highest temperature reached in °C temperature rise in °C 20.8

Show that the heat energy change (Q) for this reaction is about 2200 J. [mass of 1.0 cm³ of solution = 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 kilojoules per mole of magnesium, for the reaction between magnesium and hydrochloric acid. Include a sign in your answer. ΔH = kJ/mol

A scientist finds an unlabelled bottle on a shelf. She thinks the bottle contains a solution of ammonium sulfate, (NH₄)₂SO₄ Describe tests the scientist could do to show that the solution is ammonium sulfate.

Ammonium sulfate is often used as a fertiliser. It is prepared by reacting ammonia (NH₃) with sulfuric acid (H₂SO₄).

Name the type of reaction that occurs between ammonia and sulfuric acid.

Write a chemical equation for the reaction of ammonia with sulfuric acid.

Draw a dot‑and‑cross diagram to show the bonding in a molecule of ammonia. Show outer electrons only.

No printed figure accompanies this part — in the paper you would draw the diagram (or label the apparatus) in the answer space provided.

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 The equation for the reaction is CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

During the reaction the mass of the contents of the flask decreases.

State why the mass of the contents of the flask decreases.

State the purpose of the cotton wool.

Explain why sulfuric acid is not a suitable acid to use in this investigation.

The graph shows the student’s results

In the investigation the marble chips are in excess. Explain the shape of the graph.

The student repeats the experiment using the same volume of hydrochloric acid but of half the concentration of the original acid. All other conditions are kept the same. On the grid, draw the curve the student would obtain.

Explain, using particle collision theory, how increasing the temperature affects the rate of a reaction.

The diagram shows the apparatus a teacher uses to determine the formula of an oxide of lead. an oxide of lead hydrogen burning hole hydrogen reduction tube heat This is the teacher’s method. Step 1 find the mass of the reduction tube Step 2 add some of the lead oxide to the reduction tube Step 3 find the mass of the reduction tube and lead oxide Step 4 pass hydrogen gas over the lead oxide and ignite the hydrogen at the hole Step 5 heat the lead oxide strongly for 10 minutes Step 6 keep passing hydrogen through the reduction tube until the tube and contents are cool Step 7 find the new mass of the reduction tube and its contents

Give a reason why hydrogen is passed through the reduction tube until the tube and contents are cool.

Describe what the teacher should do next to make sure all the lead oxide has been reduced to lead. .

The teacher completes the experiment and obtains these results. mass of reduction tube = 23.50 g mass of tube + lead oxide = 28.64 g mass of tube + lead = 28.16 g

Calculate the mass of lead formed. mass of lead = g

Calculate the mass of oxygen removed from the lead oxide. mass of oxygen = g

Determine the empirical formula of the lead oxide. empirical formula of the lead oxide

The insoluble salt lead(II) chloride (PbCl₂) can be prepared by reacting a solution of lead(II) nitrate with dilute hydrochloric acid.

Complete the equation for the reaction by adding the state symbols. Pb(NO₃)₂( ) + 2HCl( ) → PbCl₂( ) + 2HNO₃( )

Show that the maximum mass of lead(II) chloride that can be made from 0.0370 mol of hydrochloric acid is about 5 g. [Mr of PbCl₂ = 278] maximum mass = g