Edexcel GCSE Chemistry Paper 2 Higher June 2025 question paper 1CH0/2H

A student carries out a flame test on a salt. The student observes a yellow flame.

Which ion is in the salt?

A molecule of a yellow substance is shown in Figure 1.

What is the formula of this molecule?

A bottle of this substance is labelled with the hazard symbol in Figure 2.

State the danger associated with the contents of this bottle.

Yellow bananas emit ethene gas, C₂H₄.

Draw one molecule of ethene, showing all covalent bonds.

Gold has a yellow colour.

A gold nanosphere has a surface area of 305 nm². The surface area to volume ratio is 1: 4.60.

Calculate the volume, in nm³, of the gold nanosphere.

When solutions P and Q are mixed together, a purple mixture forms. This mixture slowly becomes colourless.

A student pours 25 cm³ of solution P into a conical flask and then adds 25 cm³ of solution Q.

The student uses a beaker to measure out these volumes.

Name a piece of apparatus that could be used to measure these volumes more accurately.

The student investigates this reaction using the apparatus shown in Figure 3. The student measures the time taken for the cross to become visible. The experiment is repeated at different temperatures.

Figure 4 shows the results.

The concentrations of the solutions are kept constant in each experiment.

State one other variable that should be kept constant.

State, and explain in terms of particles, how the time taken for the cross to become visible would change if a temperature of 80 °C was used.

The concentration of solution Q is 26.8 g dm^–3.

Calculate the mass of solid Q present in 25 cm³ of solution Q.

The student repeats the experiment at 20 °C, with the addition of a catalyst.

Explain how the addition of a catalyst will affect the rate of reaction.

Crude oil is a mixture of hydrocarbons.

The majority of hydrocarbons in crude oil belong to one homologous series.

Give the name of this series.

When hydrocarbons undergo combustion, water is produced.

Draw a dot and cross diagram of a molecule of water.

One compound in crude oil contains 0.96 g of carbon atoms combined with 0.32 g of hydrogen atoms.

Calculate the empirical formula of this compound.

(relative atomic masses: C = 12, H = 1.0)

Crisp packets are often made from poly(propene) coated with a thin layer of aluminium on the inside.

Poly(propene) is a polymer made from the monomer propene, CH₂CHCH₃.

What is the relative formula mass of propene?

(relative atomic masses: C = 12, H = 1)

Describe how monomer molecules combine to make polymers.

Crisps go stale when exposed to the atmosphere.

In an experiment some crisp packets were made from aluminium, some from poly(propene) and some from poly(propene) coated with aluminium. These packets were tested.

Figure 5 shows the results.

Low porosity is an advantage of using poly(propene) coated with aluminium as it prevents the crisps from becoming damp.

Explain, using Figure 5, one other advantage of using poly(propene) coated with aluminium.

The aluminium coating can be replaced by a very thin layer of material called a nanosheet.

The nanosheet is made from amino acids and is less than 100 nm thick.

Explain why the nanosheet layer would be better than aluminium as a coating for crisp packets.

Nanosheet layers can be made from amino acids.

An equation showing a reaction of an amino acid, C₂H₅NO₂, is

Calculate the mass of water formed when 105 g of this amino acid reacts.

(relative formula masses: C₂H₅NO₂ = 75, H₂O = 18)

Some crisps contain malic acid.

The structure of one molecule of malic acid is shown in Figure 6.

Malic acid has two types of functional group.

One type is the –COOH functional group.

Give the name of this functional group.

Name the other functional group.

Group 1 elements are known as the alkali metals.

Which row gives two physical properties of the alkali metals?

The alkali metals react with water.

A teacher adds a small piece of potassium to water.

Give two observations that would be seen.

The reaction of lithium with water is much less vigorous than the reaction of potassium with water.

Explain why, in terms of their electronic configurations.

When sodium reacts with water, a solution of sodium hydroxide is formed.

When the solution is left in air, the hydroxide ions react with carbon dioxide, forming carbonate ions, CO₃^2–, and one other product.

Complete the ionic equation for this reaction.

_........ OH^– +_........ CO₃^2– +_........

The relative atomic mass of caesium is 132.905.

Calculate the average mass of one atom of caesium.

(Avogadro constant = 6.02 × 10²³)

This question is about the noble gas xenon.

Xenon is unreactive.

Explain, in terms of its electronic configuration, why xenon is unreactive.

Under extreme conditions, xenon can be made to react with fluorine to form xenon tetrafluoride, XeF₄.

Write the balanced equation for this reaction.

Some information about xenon tetrafluoride is shown in Figure 7.

State and explain, with reasons, the type of structure and bonding in xenon tetrafluoride.

Under extreme conditions, xenon reacts with fluorine to form xenon hexafluoride.

The reaction is exothermic. The energy change for the reaction is –400 kJ mol^–1.

On Figure 8

• add a label to the y‑axis

• draw the reaction profile for this reaction

• label the energy change and the activation energy for the reaction.

This question is about carbon and some carbon compounds.

Two forms of pure carbon are graphite and Buckminsterfullerene.

Explain why graphite is used as a lubricant.

Calculate the mass, in kg, of five moles of Buckminsterfullerene, C₆₀.

(relative atomic mass: C = 12)

A molecule in an homologous series has the formula C₉H₂₁N.

What is the formula of the next molecule in this homologous series?

A Bunsen burner burns methane gas, CH₄.

A student investigates the time taken to heat up a beaker of water using this Bunsen burner.

Figure 9 shows the apparatus used.

The student sees that a large amount of carbon forms as a black solid on the underside of the gauze.

The teacher said that the investigation would be improved if no carbon forms.

Explain what the student should do to stop carbon forming on the underside of the gauze.

*(d) Natural processes and human activities change the amount of carbon dioxide in the atmosphere.

Figure 10 shows the concentration of carbon dioxide in the atmosphere measured in one location and the mean global temperature from 1960 to 2000.

Evaluate whether the data in Figure 10 shows that the change in the amount of carbon dioxide is leading to climate change.

Your answer should include

• the natural processes that change the amount of carbon dioxide in the atmosphere

• the human activities that change the amount of carbon dioxide in the atmosphere

• how carbon dioxide contributes to the greenhouse effect and climate change.

This question is about molecules containing two atoms.

In an experiment, hydrochloric acid is reacted with zinc.

The volume of gas produced is measured by collecting the gas in an upturned measuring cylinder over water.

Give a method of collecting and measuring the gas that would give a more accurate volume of gas.

Iodine has an atomic number of 53 and a mass number of 127.

How many electrons are there in an iodine molecule, I₂?

Iodine reacts with hydrogen to form hydrogen iodide, H I.

Explain whether or not a solution of hydrogen iodide in water conducts electricity.

Chlorine gas is bubbled through a colourless solution of potassium bromide, KBr. The mixture turns orange.

Give the name of the substance that causes the orange colour.

Write the balanced equation for this reaction.

Hydrogen iodide reacts with oxygen to form water and iodine.

The equation for this reaction is

Calculate the energy change for this reaction using the bond energies in Figure 11.

Include a sign and unit in your answer.

Figure 12 shows the calibration graph of a flame photometer for the concentration of calcium ions in a solution.

concentration of calcium ions in mg dm^–3

Figure 12

Use Figure 12 to find the concentration of calcium ions when the photometer reading is 175.

A flame photometer was used to measure the concentration of sodium ions in tap water and three types of bottled water.

The results are shown in Figure 13.

Calculate the mean concentration of sodium ions in the three bottled waters.

mean concentration =_........ mg dm

Calculate the volume of tap water, in dm³, that contains 3 moles of sodium ions.

(relative atomic mass: Na = 23)

A student is given two test tubes, one containing solid aluminium chloride and the other containing solid calcium chloride.

Describe the test the student should use to show which solid is in which test tube, giving the observation for each compound.

Silver carbonate and silver bromide are both insoluble solids.

A student tests a solution to see if it contains bromide ions. The student adds a few drops of silver nitrate solution. A precipitate forms.

The student repeats the test but adds some dilute nitric acid before adding the silver nitrate solution. The mixture fizzes and no precipitate forms.

Explain what conclusion the student can draw from these results.

Ethanol can be produced by the fermentation of carbohydrates.

What conditions are necessary for fermentation?

A carbohydrate has the formula C₁₂H₂₄O₁₂.

Complete the equation for the fermentation of this carbohydrate to make ethanol and carbon dioxide only.

C₁₂H₂₄O_{12 ........}

Ethanol can be oxidised to make ethanoic acid. One use of ethanoic acid is to make a monomer.

This monomer is polymerised to make the addition polymer PVA, used as a glue.

The structure of the monomer is shown in Figure 14.

Draw a diagram to show the structure of the repeating unit of PVA.

*(c) Babies may wear bamboo nappies or disposable nappies. Both types of nappy absorb liquid.

The bamboo in bamboo nappies comes from a fast growing plant. A bamboo nappy can be washed and used again many times. When a bamboo nappy is placed in landfill, it will rot away quickly.

Disposable nappies contain a polymer made using crude oil. 1 g of a typical polymer used in disposable nappies can absorb about 150 g water. When a disposable nappy is placed in landfill, it may take over 400 years to decompose.

Discuss, using the information given, the advantages and disadvantages of bamboo nappies and disposable nappies. Include in your answer a brief description of how a nappy could be tested to see how much water it will absorb.