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

Figure 1 shows a chemical cell.

The chemical cell contains two metal electrodes placed into an electrolyte and connected in a circuit with a voltmeter.

State what type of compound must be present in the electrolyte.

When the two metal electrodes are placed in the electrolyte, a voltage is produced.

The bigger the difference in reactivity of the metals, the larger the voltage produced.

Which metal, when used for electrode X in Figure 1, would give the largest voltage?

State what happens to the voltage when one of the reactants is used up.

Hydrogen-oxygen fuel cells can also be used to produce a voltage.

Draw the dot and cross diagram for a molecule of oxygen, O₂.

An atom of oxygen has the electronic configuration of 2.6.

Show outer electrons only.

Hydrogen‑oxygen fuel cells are used in spacecraft.

Suggest one advantage of using fuel cells rather than chemical cells in spacecraft.

Atoms of neon are made up of subatomic particles.

Figure 2 shows some information about the subatomic particles in neon atoms.

Complete Figure 2 with the missing information.

All atoms of neon have an atomic number of 10.

Describe what information about the number of subatomic particles can be obtained from the atomic number of neon.

Explain why atoms of neon are electrically neutral.

A sample of neon contains three isotopes

90.48% of neon-20

0.27% of neon-21

9.25% of neon-22

Using this information, calculate the relative atomic mass of this sample of neon.

relative atomic mass =_........

Silver nitrate and potassium chloride are ionic compounds that are soluble in water.

When potassium chloride solution is added to a solution of silver nitrate, a white precipitate forms.

Complete the equation for this reaction, including the missing state symbol.

Give the name of the white precipitate that forms.

State and explain how the white precipitate can be separated from the reaction mixture.

Silver nitrate solution conducts electricity. Solid silver also conducts electricity.

Describe how silver nitrate solution conducts electricity and how solid silver conducts electricity.

Phosphoric acid is important in the production of fertilisers.

A few drops of litmus solution are added to a sample of dilute phosphoric acid.

What is the colour of the mixture formed?

State why litmus cannot be used to measure pH.

Phosphoric acid can react to form phosphate salts which are used in fertilisers.

Give two reasons why farmers use fertilisers on their fields.

An experiment was carried out to produce phosphoric acid.

The actual yield for the experiment was 18.62 g.

The theoretical yield for the experiment is 24.50 g.

Calculate the percentage yield of this experiment.

percentage yield =_........

The equation for a reaction to make phosphoric acid, H₃PO₄, is

Calculate the atom economy for the production of phosphoric acid in this reaction.

(relative formula masses: Ca₅(PO₄)₃OH = 502, H₂SO₄ = 98, H₃PO₄ = 98, CaSO₄ = 136, H₂O=18)

atom economy =_........

The equation for a reaction to produce phosphoric acid is

Explain how the atom economy of the reaction can be increased.

Nitrogen, N₂, oxygen, O₂ and fluorine F₂ are all gases.

Nitrogen, oxygen and fluorine are in the same period of the periodic table.

Explain, in terms of electronic configuration, in which period of the periodic table nitrogen, oxygen and fluorine are located.

Fluorine has a boiling point of –188 °C.

Explain why fluorine has a low boiling point.

A mixture of nitrogen and oxygen becomes a liquid when cooled to –200 °C.

Which row shows the changes in energy and movement of the molecules as they are cooled from room temperature to –200 °C?

The mixture of liquid nitrogen and liquid oxygen can be separated.

Which process could be used to separate a mixture of liquid nitrogen and liquid oxygen?

At high temperatures, nitrogen, N₂, can react with oxygen, O₂, to form nitrogen dioxide only.

Write the balanced equation for this reaction.

Malachite, Cu₂CO₃(OH)₂, is a mineral containing copper.

When heated, malachite decomposes to form copper oxide, carbon dioxide and water.

Which apparatus should be used to heat the malachite and test for carbon dioxide?

When carbon dioxide is bubbled through limewater, a precipitate forms. This precipitate solid makes the limewater cloudy.

Name the precipitate that makes the limewater cloudy.

The equation for the decomposition of malachite when it is heated is

Calculate the maximum mass of copper oxide that can be formed when 22.1 g of malachite is decomposed completely.

(relative atomic masses: Cu = 63.5, O = 16.0, C = 12.0, H = 1.0)

maximum mass of CuO =_........

Copper can be extracted from copper oxide by heating the copper oxide with carbon.

A student investigated two methods to extract the maximum mass of copper from copper oxide.

Figure 3 shows the two methods.

Comment on the strengths and weaknesses of these two methods.

Copper, iron, nickel and zinc are all metallic elements.

Which row of the table applies to copper?

Many ships are made of steel. Steel is an alloy that contains iron. Figure 4 shows blocks of zinc attached to a steel ship.

Explain how iron is protected from rusting by the zinc blocks.

Alloys of copper and nickel are used for some coins.

Figure 5 shows the relative strengths of copper and nickel and some of their alloys.

On Figure 6

• add suitable scales to the vertical and horizontal axes

• plot a graph of relative strength against percentage of nickel

• draw a curve of best fit.

A coin is made from an alloy that contains 70% copper and 30% nickel.

Determine the relative strength of this coin from your graph on Figure 6.

relative strength of the coin =_........

Explain, using Figure 6, how the percentage of nickel affects the relative strength of the alloys of copper and nickel.

Magnesium sulfate is an ionic compound.

A student adds magnesium sulfate to water to form a solution.

Which of these will also form a solution when added to water?

Calculate the percentage by mass of oxygen in magnesium sulfate, MgSO₄.

(relative atomic mass: O = 16.0 relative formula mass: MgSO₄ = 120)

Give your answer to 3 significant figures.

percentage by mass =_........

Calculate the number of oxygen atoms in 7.20 g of MgSO₄.

(relative formula mass: MgSO₄ = 120 Avogadro constant = 6.02 × 10²³)

number of oxygen atoms =_........

*(c) Magnesium sulfate solution can be electrolysed using the apparatus shown in Figure 7.

Explain how the products are formed at the electrodes in terms of

• the ions present in the solution

• the oxidation and reduction reactions that take place at the electrodes.

You should include ionic equations as part of your answer.

This question is about ammonia.

Ammonia is a gas.

Suggest why the litmus paper used to test for ammonia gas has to be damp.

Ammonia can be made on an industrial scale using the Haber process.

The equation for the reaction is

The reaction can reach a dynamic equilibrium.

Explain what happens when the reaction reaches dynamic equilibrium

Figure 8 shows the changes in percentage yield of ammonia at equilibrium as temperature increases, at a pressure of 300 atmospheres and at a pressure of 1000 atmospheres.

Which row of the table will give the highest percentage yield of ammonia at equilibrium?

In industry, a pressure of 200 atmospheres is used for the Haber process.

Using Figure 8, explain what happens to the position of dynamic equilibrium if the process is carried out at 100 atmospheres.

Ammonia can also be made by heating ammonium chloride.

A sample of solid ammonium chloride is heated in a boiling tube.

After a few minutes ammonium chloride, a white solid, is also seen at the top of the boiling tube, as shown in Figure 9.

Explain how ammonium chloride is formed at the top of the boiling tube.

A student is asked to carry out a titration to find the concentration of a sodium hydroxide solution.

A teacher dilutes some sulfuric acid with distilled water to make a solution with a concentration of 0.250 mol dm^–3 for the student to use.

What effect does diluting the sulfuric acid with distilled water have on the pH of the solution and the concentration of the H⁺ ions?

What is the concentration, in g dm^–3, of a 0.250 mol dm^–3 solution of H₂SO₄?

(relative formula mass: H₂SO₄ = 98.0)

The student uses the apparatus shown in Figure 10 to carry out the titration.

Before using the apparatus, the student rinses the burette with distilled water.

This is an error.

Explain what effect this error has on the result of the titration.

State what the student should do to correct the error.

*(c) The equation for the reaction in the titration is

Explain how the equation for the reaction and the apparatus in Figure 10 can be used to find the concentration of 25.0 cm³ of sodium hydroxide solution using the 0.250 mol dm^–3 sulfuric acid.