4CH1/1C — November 2023 (Edexcel IGCSE Chemistry): Past Paper

A substance can exist in three states of matter, solid, liquid or gas. When a liquid evaporates at room temperature it changes into a gas.

Complete the diagram to show the arrangement of another four particles in a gas.

Explain why heating a liquid causes it to evaporate more quickly.

When the temperature decreases, water in the gas state changes to a liquid.

Give the name of this change of state.

Write an equation, including state symbols, to show the change of state of water from a gas to a liquid.

Describe the arrangement and movement of particles in a solid.

Table 1 shows some relative masses and charges of subatomic particles. Complete table 1 by giving the missing information. Electron Proton Neutron Relative mass 0.0005 Relative charge 0 Table 1

Table 2 gives the number of protons, neutrons and electrons in atoms and ions of some elements. The letters are not the symbols of the elements

What is the atomic number of P in table 2?

What is the mass number of U in table 2?

Give the letter in table 2 that represents an element in Group 5 of the Periodic Table.

Q and R represent isotopes of the same element.

Explain, in terms of subatomic particles, why Q and R are isotopes.

A sample containing the isotopes Q and R has this percentage composition by mass. Q = 20.6 % R = 79.4 % Calculate the relative atomic mass (Ar) of this sample of the element. Give your answer to one decimal place. Ar =

Crude oil is an important source of organic compounds.

The diagram shows how crude oil can be separated into useful mixtures of hydrocarbons. F E D X C B crude oil A

Give the name of this method of separation.

State what happens to the crude oil when it is in X.

Give the letter of the mixture that is most likely to contain a hydrocarbon with six carbon atoms.

Give the name of mixture D.

Give a use for mixture B.

Explain, in terms of intermolecular forces, why a hydrocarbon in mixture B has a higher boiling point than a hydrocarbon in mixture D.

Catalytic cracking can be used to break down long‑chain hydrocarbons to produce shorter‑chain alkanes and alkenes.

Give the name of a catalyst used in catalytic cracking.

Complete the equation to show two different alkenes that could be produced in this cracking reaction. C₁₅H₃₂ → C₈H₁₈ + +

Give one important use for short‑chain alkenes.

This question is about gases.

The table gives information about five gases. carbon Name of gas argon hydrogen oxygen nitrogen dioxide Formula of gas Ar CO₂ H₂ O₂ N₂ Mr of gas 40 2 32 28 Use information from the table to answer these questions. Each gas may be used once, more than once or not at all.

Give the name of the gas that is about 79 % of the atmosphere by volume.

Give the name of the gas that is a compound.

Give the name of the least reactive gas.

Give the name of the gas that is not normally found in the atmosphere.

Give the name of the gas that affects global warming.

Calculate the Mr for carbon dioxide. Mr =

Give a reason why it is not possible to give information for air in the table.

When copper(II) carbonate is heated, the products are copper(II) oxide and carbon dioxide.

Give the name for this type of reaction.

Give the colour change that occurs during this reaction to

Give a chemical equation for this reaction.

This question is about alkanes and alkenes.

The alkane C₄H₁₀ exists as two isomers.

State what is meant by the term isomers.

Draw the displayed formulae for the two isomers of C₄H₁₀ Isomer 1 Isomer 2

Ethane (C₂H₆) can react with bromine.

State the condition needed for ethane to react with bromine.

Complete the equation for this reaction. C₂H₆ + Br₂ → +

Give the name for this type of reaction.

Explain why ethane is described as a saturated compound.

State what you would observe when ethane and ethene are added separately to two samples of bromine water. ethane ethene

Explain why straight‑chain alkenes always have the same empirical formula, but straight‑chain alkanes have different empirical formulae. Refer to the molecular formulae of the alkanes C₂H₆ and C₄H₁₀ in your answer.

An organic compound has this percentage composition by mass. C = 19.2 % H = 4.0 % O = 12.8 % Br = 64.0 % Calculate the empirical formula of this compound. empirical formula =

A student uses this apparatus to investigate the decomposition of hydrogen peroxide solution. 0 20 40 60 80 100 cm³ hydrogen peroxide solution oxygen manganese(IV) oxide This is the equation for the reaction. 2H₂O₂ → 2H₂O + O₂

Give the test for oxygen.

Complete the dot‑and‑cross diagram for a molecule of hydrogen peroxide. Show outer electrons only. H O O H

The student measures the volume of oxygen collected at regular intervals until the reaction stops. The table shows the student’s results. Time in seconds 0 20 40 60 80 100 120 140 160 Volume of oxygen in cm³ 0 24 44 62 78 88 94 94 94

Plot the student’s results on the grid.

Draw a curve of best fit. 100 Volume of oxygen in cm³ 0 20 40 60 80 100 120 140 160 Time in seconds

Explain in terms of particle collision theory how decreasing the concentration affects the rate of a reaction.

The student repeats the experiment using the same volume of hydrogen peroxide solution but with half the original concentration. All other conditions are kept the same. On the grid, draw the curve you would expect the student to obtain.

In this reaction, the manganese(IV) oxide acts as a catalyst. Explain how a catalyst works.

A technician needs to identify the solution in an unlabelled bottle. The technician knows that the solution contains one of these compounds. • iron(II) bromide • iron(II) chloride • iron(III) bromide • iron(III) chloride Describe how the technician can use chemical tests to identify the compound.

When chlorine gas is passed over heated iron powder, iron(III) chloride forms. This is the equation for the reaction. 2Fe + 3Cl₂ → 2FeCl₃ 0.060 mol of chlorine gas is passed over 2.8 g of iron powder. Show by calculation that the iron powder is in excess.

When iron(III) chloride dissolves in water, an acidic solution forms.

Give the colour of litmus in this solution.

Give the formula of the ion that causes the solution to be acidic.

Diamond and graphite are made of carbon atoms, joined together by covalent bonds. The diagram shows their structures.

State, in terms of electrostatic attractions, what is meant by a covalent bond.

Explain why diamond has a high melting point.

Explain why graphite is a good conductor of electricity.

C₆₀ fullerene is a molecule made of 60 carbon atoms. The diagram shows the structure of C₆₀ fullerene. One mole of atoms contains 6.0 × 10²³ atoms. Determine the number of atoms in one mole of C₆₀ fullerene. Give your answer in standard form. number of atoms =

A scientist uses this apparatus in an experiment to reduce a metal oxide to a metal. hydrogen metal oxide burning hydrogen tube heat Before heating the mass of the empty tube and the mass of the tube and the metal oxide are recorded. After heating, the tube is allowed to cool and the mass of the tube and its contents is recorded again.

State why the reaction of the metal oxide to form a metal is described as a reduction reaction.

State why it is important to relight the hydrogen at the end of the tube if the flame goes out.

Explain why it is important to continue passing hydrogen into the tube and burning the hydrogen at the end of the tube until the contents have cooled.

Describe what should be done next to ensure that all the metal oxide has been converted into the metal.

In this experiment a mass of 4.14 g of metal is formed from 4.46 g of the metal oxide.

Calculate the amount, in moles, of oxygen atoms in the sample of the metal oxide. amount of oxygen atoms = mol

The formula of the metal oxide is MO, where M represents the symbol of the metal. Deduce the amount, in moles, of M in the sample of the metal oxide. amount of M = mol

Calculate the relative atomic mass of M. relative atomic mass of M =

Use the Periodic Table to identify metal M.

This method is used in an experiment to produce hydrated zinc nitrate crystals.

• pour 50 cm³ of dilute nitric acid into a beaker
• add a spatula of zinc powder to the acid
• add more zinc until it is in excess
• filter the mixture
• obtain crystals of zinc nitrate from the filtrate

State why the mixture is filtered.

Describe how a pure, dry sample of hydrated zinc nitrate crystals could be obtained from the filtrate.

This equation represents the formation of hydrated zinc nitrate in the experiment. Zn(s) + 2HNO₃(aq) + 6H₂O(l) → Zn(NO₃)₂.6H₂O(aq) + H₂(g)

In another experiment, 9.75 g of zinc is completely reacted with nitric acid. Show that the maximum possible mass of hydrated zinc nitrate crystals that could be formed is approximately 45 g. [for Zn(NO₃)₂.6H₂O, Mr = 297]

The actual yield of hydrated zinc nitrate crystals is 36.4 g. Calculate the percentage yield of hydrated zinc nitrate crystals. percentage yield = %