Practice Paper 2 (Edexcel IGCSE Chemistry)

This question is about the percentage of oxygen in the air.

The percentage of oxygen in the air can be determined by observing the formation of hydrated iron(III) oxide.

Write the balanced chemical equation for the formation of iron(III) oxide from iron.

A student sets up this apparatus to observe the formation of hydrated iron(III) oxide.

The reading on the syringe is recorded at the start of the experiment. The apparatus is then left for a week before the reading on the syringe is recorded again.

The table shows the initial reading of the syringe.

The atmosphere is comprised of 20% oxygen. Complete the table to show the expected results.

A student completes a second experiment.

The diagram shows the readings on the student's experiment.

The student completes their results table, as shown, to calculate that the percentage of oxygen in the air is 21.5%.

Identify the error that the student has made and calculate the correct percentage of oxygen in the air.

Another set of experiments featured changes to the apparatus.

i) Explain how the use of dry iron filings would affect the calculated percentage of oxygen in the air.

ii) Explain how leaving the apparatus in a warm place for 1 week would affect the calculated percentage of oxygen in the air.

A compound is suspected of containing copper ions, Cu²⁺ and bromide ions, Br^-.

Which test would not help to positively identify copper ions or bromide ions?

This question is about the elements in Group 1 of the Periodic Table and their reactions with water.

State why sodium and potassium are in Group 1 of the Periodic Table.

A reaction occurs when a small piece of sodium is added to a large volume of water in a trough.

i) Give two observations that you would make during this reaction.

ii) After the reaction has finished, a few drops of universal indicator are added to the solution in the trough. Explain the final colour of the universal indicator.

iii) What is the most likely pH value of the solution in the trough after the reaction is complete?

Give the name of a Group 1 metal that is less reactive than sodium.

A small piece of potassium is added to a large volume of water in a trough. Give one observation that is made when potassium is added to water that is not made when sodium is added to water.

Complete the equation for the reaction of rubidium with water. State symbols are not required.

........Rb + ........H₂O → ........RbOH + .........H₂

This question is about some of the halogens and their compounds.

i) Which element is a liquid at room temperature?

ii) Which element has the palest colour?

iii) Which element is the least reactive?

A teacher uses displacement reactions to demonstrate the reactivities of some halogens. She adds solutions of chlorine, bromine and iodine separately to three different sodium halide solutions. The table shows some of the teacher’s results.

A change in colour of the solution indicates that a reaction has occurred.

i) Complete the table by predicting the missing results.

ii) State why the teacher does not add bromine solution to sodium bromide solution.

iii) The word equation for the reaction of bromine with sodium iodide is

bromine + sodium iodide → iodine + sodium bromide

Write a chemical equation for this reaction.

A technician sees an unlabelled bottle containing a liquid. He knows that the liquid is a solution of one of these compounds.

• copper(II) chloride
• copper(II) bromide
• iron(II) chloride
• iron(II) bromide

Describe chemical tests that the technician could use to identify the compound in the solution.

Separate: Chemistry Only

Which of the following reactions does not involve the oxidation of ethanol?

What is the empirical formula of butanoic acid?

Separate: Chemistry Only

This question is about esters.

Ester A reacts with water to form ethanoic acid and ethanol.

The displayed formulae of the reactants and products are shown in this equation

The molar enthalpy change (ΔH) for the reaction is 0 kJ / mol.

i) Draw a ring around the functional group in ester A.

ii) Give the name of ester A.

iii) Describe a chemical test, other than using an indicator, to show that the reaction mixture contains ethanoic acid.

Separate: Chemistry Only

Explain why the molar enthalpy change (ΔH) for the reaction between ester A and water is 0 kJ / mol.

In your answer, refer to the bonds broken and the bonds formed.

Separate: Chemistry Only

A mixture of ester A and water is left in a sealed container until the reaction mixture reaches dynamic equilibrium.

i) Describe what is meant by dynamic equilibrium.

ii) Explain why adding a catalyst does not change the position of equilibrium.

Separate: Chemistry Only

The ethanoic acid produced in the reaction is completely neutralised by 22.75 cm³ of 0.150 mol / dm³ barium hydroxide solution.

The equation for the neutralisation reaction is

2CH₃COOH + Ba(OH)₂ → Ba(CH₃COO)₂ + 2H₂O

Calculate the amount, in moles, of ethanoic acid neutralised.

Give your answer to 3 significant figures.

amount = .............................. mol

Separate: Chemistry Only

The structures of two organic compounds are shown.

These compounds react together to form a polymer.

Give the repeat unit of the polymer formed.

Which of the following statements about polymers is NOT correct?

A student uses this apparatus to investigate the rate of reaction between excess marble chips and dilute hydrochloric acid.

i) Give the equation for the reaction.

ii) Explain what happens to the mass of the flask contents during the reaction.

iii) Explain how the result of the investigation could change if the experiment were carried out without the cotton wool.

The graph shows the student's results.

Explain the shape of the graph.

The student repeats the experiment using the same mass of smaller marble chips and the same volume and concentration of acid.

i) On the same grid, draw the shape of the curve obtained.

ii) Explain the shape of the curve with smaller chips.

Explain, using collision theory, how doubling the concentration of the acid affects the rate of reaction.

This question is about ammonia gas, NH₃

Ammonia can be prepared in a laboratory from the reaction between ammonium chloride, NH₄Cl, and sodium hydroxide. The other products of the reaction are sodium chloride and water.

i) Give a chemical equation for this reaction.

ii) Give a test for ammonia gas.

Separate: Chemistry Only

In industry, ammonia is produced from nitrogen and hydrogen. The equation for this reaction is

N₂ (g) + 3H₂ (g) $\rightleftharpoons$ 2NH₃ (g)

In a sealed container, the reaction can reach a position of dynamic equilibrium. Explain the meaning of the term dynamic equilibrium.

Separate: Chemistry Only

The graph shows the percentage yield of ammonia at equilibrium for different temperatures and pressures.

Using the graph, explain if the forward reaction is exothermic or endothermic.

The diagram shows the structures of three substances that have giant covalent structures.

Which does not provide the correct explanation of the property of a substance?