Edexcel IGCSE Chemistry Chemistry Paper 1 June 2023 question paper 4CH1/1CR

This question is about oxygen.

Oxygen can be stored in tanks as a liquid or as a gas.

Complete the diagram to show the arrangement of six more particles in a gas.

Give a reason why a tank can store much more oxygen as a liquid.

Identify a hazard when storing oxygen as a gas.

Sulfur burns in oxygen to form sulfur dioxide.

Give one observation that can be made when sulfur burns in oxygen.

Some universal indicator is added to sulfur dioxide.

Explain the final colour of the universal indicator.

This question is about mixtures and compounds.

The box gives some techniques used to separate mixtures.

The table lists some substances and mixtures.

Complete the table using words from the box to show the best technique to obtain the named substance from each mixture.

Each technique may be used once, more than once or not at all.

State how the box represents a mixture.

Food colourings are mixtures of food dyes.

A student uses paper chromatography to separate the food dyes contained in food colouring D.

The student places spots of three food dyes A, B and C and food colouring D on chromatography paper.

The diagram shows the appearance of the paper after the experiment.

Describe the composition of food colouring D.

A compound has the formula Ca(HCO₃)₂

Determine the number of different elements in Ca(HCO₃)₂

Determine the number of atoms in the formula of Ca(HCO₃)₂

The diagram represents an atom of an element.

What is the particle labelled W?

An atom of this element contains 13 neutrons.

What is the mass number of this element?

State why atoms have no overall charge.

What is the charge on the ion usually formed from this element?

There are two isotopes of the element lithium.

State why both isotopes react in the same way.

A sample of lithium contains 7.60%₃⁶Li and 92.4%⁷₃Li

Calculate the relative atomic mass, A_r, of this sample of lithium.

Give your answer to two decimal places.

This question is about gases.

The table gives information about some gases.

Complete the table by choosing a gas from the box that matches the information.

You may use each gas once, more than once, or not at all.

A teacher uses this apparatus to determine the percentage of oxygen in a sample of air.

This is the teacher’s method.

• record the total volume of air in the apparatus

• heat the copper powder

• use the syringes to pass air over the heated copper powder several times

• allow the remaining gas to cool and record its volume

The copper powder turns black.

State why the copper powder turns black.

Give a reason why the remaining gas is allowed to cool before its volume is recorded.

At the start of the experiment, the total volume of air in the apparatus is 138 cm³.

At the end of the experiment, the volume of gas remaining is 108 cm³.

Calculate the percentage of oxygen in the sample of air.

Assume that all the oxygen has reacted.

This question is about iron.

One problem with iron is that it rusts.

Name the two substances that iron reacts with when it rusts.

State what type of reaction occurs when iron rusts.

Iron can be prevented from rusting by painting or by coating with zinc.

Explain how painting prevents iron from rusting.

Name the process used to coat iron with zinc.

Explain why a layer of zinc protects iron from rusting, even if the layer of zinc is scratched.

Iron is formed when aluminium reacts with iron(III) oxide.

This is the equation for the reaction.

Explain what this reaction shows about the relative reactivities of aluminium and iron.

Explain which substance acts as an oxidising agent in this reaction.

A student uses this apparatus to investigate the rate of reaction when hydrogen peroxide solution decomposes.

This is the equation for the reaction.

Give a reason why the gas that collects in the gas syringe is not pure oxygen.

The rate of reaction can be increased by adding a catalyst to the hydrogen peroxide solution.

Describe how a catalyst increases the rate of a reaction.

These solids catalyse the decomposition of hydrogen peroxide solution.

• lead(IV) oxide

• manganese(IV) oxide

Describe a method that the student could use to find out which solid is the more effective catalyst.

A student investigates the decomposition of a solution of hydrogen peroxide at different temperatures.

The graph shows how the total volume of oxygen collected in the syringe changes with time when the solution is at a temperature of 20 °C.

On the grid, draw the curve the student would obtain at a temperature of 40 °C when all other conditions are kept the same.

A teacher uses this apparatus to test the products of the combustion of liquid hydrocarbons.

Explain the change in appearance that occurs in the limewater.

The equation represents the complete combustion of an alkene.

C_nH_2n + oxygen carbon dioxide + nH₂O

Complete combustion of 0.0100 mol of the alkene produces 2.16 g of water.

Determine the molecular formula of this alkene.

[for H₂O, M_r = 18]

Give a reason why the mass of pure water that collects in the U-tube is less than 2.16 g.

Give a physical test to show that the water that collects in the U-tube is pure.

The teacher burns 30.0 g of heptane.

This is the equation for the complete combustion of heptane.

Calculate the minimum mass of oxygen needed for the complete combustion of 30.0 g of heptane.

[for C₇H₁₆, M_r = 100 for O₂, M_r = 32]

Diamond, graphite and C₆₀ fullerene are all forms of the element carbon.

The diagram shows the structures of these three substances.

Explain why graphite conducts electricity.

Explain why diamond is hard but graphite is soft.

Doctors use C₆₀ fullerene to deliver medicines to certain parts of the body, so that the medicine does not damage other parts of the body.

Suggest why C₆₀ fullerene is suitable for this purpose.

This question is about ionic compounds.

Calcium nitrate has the formula Ca(NO₃)₂

Give the formula of each ion in calcium nitrate.

calcium ion

nitrate ion

Explain why calcium nitrate has a high melting point.

Refer to structure and bonding in your answer.

Calcium nitrate decomposes when heated.

Complete the chemical equation for the decomposition of calcium nitrate.

A student has four unlabelled beakers, each containing a colourless solution of a different salt.

These are the four salt solutions.

• calcium bromide

• calcium chloride

• sodium chloride

• sodium sulfate

Describe a series of tests to identify each solution.

Do not refer to safety precautions in your answer.

This question is about propene.

The structural formula of propene is CH₃CH CH₂

Complete the dot-and-cross diagram for a molecule of propene.

Describe the forces of attraction that hold the atoms together in a molecule of propene.

The alkane pentadecane has the formula C₁₅H₃₂

Describe how propene can be produced from pentadecane.

Propene is used to make poly(propene).

Complete the equation for the formation of poly(propene).

Explain why the disposal of poly(propene) in landfill sites is a problem.

Propene can be converted into compound X.

Compound X contains these percentages by mass.

• carbon 60%

• hydrogen 13.3%

• oxygen 26.7%

Compound X has an M_r of 60

Determine the molecular formula of compound X.

Propene and compound X both have simple molecular structures.

Explain why compound X has a higher boiling point than propene.

A student uses this method to investigate the temperature change when solid sodium hydrogencarbonate is added to ethanoic acid solution.

• pour 100 cm³ of ethanoic acid solution into a polystyrene cup

• record the temperature of the ethanoic acid solution

• add a 1 g portion of sodium hydrogencarbonate to the ethanoic acid solution and stir

• record the new temperature

• add further 1 g portions of sodium hydrogencarbonate, stirring and recording the temperature after each portion is added

The table shows the student’s results.

Plot the student’s results on the grid.

Draw a circle around the anomalous result.

Draw a curve of best fit.

Explain why using a polystyrene cup makes the results more accurate.

Suggest a mistake the student might have made to cause the anomalous result.

State how the results show the reaction is complete.

State how the results show that the reaction is endothermic.

Use the results to calculate the heat energy change, Q, in joules.

[for 1.0 cm³ of ethanoic acid solution, mass = 1.0 g]

[for ethanoic acid solution, c = 4.2 J / g / °C]

The student repeats the experiment starting with a different volume of ethanoic acid solution.

The student uses 7.0 g of sodium hydrogencarbonate to neutralise the ethanoic acid solution.

The heat energy change, Q, is 3200 J.

Calculate the molar enthalpy change, Δ H, in kJ / mol.

Include a sign with your answer.

[for sodium hydrogencarbonate, M_r = 84]

ΔH =_........ kJ / mol