Chemistry

4CH1/2C — November 2024 (Edexcel IGCSE Chemistry): Past Paper

Exam code:4CH1

7 questions · 70 marks · ≈ 70 min

Reconstructed — 7 questions held from this paper, in paper order

Guided practice

17 marks

1 mark

(a)(i)

The table shows information about five species, A, B, C, D and E.

Species	Number of protons	Number of neutrons	Number of electrons
A	1	0	1
B	3	3	3
C	3	4	3
D	9	10	10
E	13	14	13

Use the table to answer these questions. You may use each letter once, more than once, or not at all.

Give the letter of the species that is a negative ion.

Your answer

1 mark

(a)(ii)

Give the letter of the species that has a full outer shell of electrons.

Your answer

1 mark

(a)(iii)

Give the letter of the species that has an atomic number equal to its mass number.

Your answer

2 marks

(b)

Explain why species B and C are atoms of the same element with identical chemical properties.

Your answer

2 marks

(c)

A proton has a mass of 1.6726 × 10–24 g. A neutron has a mass of 1.6740 × 10–24 g. Calculate the mass, in grams, of the nucleus of an atom of species C. mass = g

Your answer

How did you do?/ 7

28 marks

2 marks

(a)(i)

This question is about metals and metal compounds.

All metals are malleable and good conductors of electricity. The diagram shows the structure of a metal. + + + + + metal ion + + + + electron + + + + +

Explain why metals are malleable.

Your answer

2 marks

(a)(ii)

Explain why metals are good conductors of electricity.

Your answer

2 marks

(b)

Two methods of obtaining a metal from a compound are electrolysis and extraction using carbon. Explain, without giving practical details, which method is most suitable for extracting iron from iron(III) oxide.

Your answer

2 marks

(c)

A student has a solution of iron(II) sulfate and a solution of iron(III) sulfate. Describe a chemical test the student could use to identify which solution is iron(II) sulfate.

Your answer

How did you do?/ 8

36 marks

(a)

A student uses this apparatus to separate a mixture of ethanol and water.

apparatus — official paper figure (qp.pdf p.8)

Give the name of this method of separation.

Choose your answer

chromatography

crystallisation

filtration

fractional distillation

3 marks

(b)

Name the pieces of apparatus labelled X, Y and Z. X Y Z

apparatus — official paper figure (qp.pdf p.8) (same figure as asset_3_b_apparatus_stem)

Your answer

2 marks

(c)

Give a physical test that the teacher could do to find out if the ethanol produced is pure.

Your answer

How did you do?/ 6

411 marks

2 marks

(a)(i)

A teacher adds a small piece of lithium to water and collects the gas produced.

Give two observations when lithium is added to water. 1 2

Your answer

2 marks

(a)(ii)

The teacher adds a few drops of universal indicator to the solution at the end of the reaction. Explain the final colour of the universal indicator.

Your answer

3 marks

(b)

This is the equation for the reaction between lithium and water. 2Li(s) + 2H₂O(l) → 2LiOH(aq) + H₂(g) The teacher collects 550 cm³ of hydrogen at rtp. Calculate the mass, in grams, of lithium that the teacher added to the water. [one mole of gas at rtp has a volume of 24 000 cm³] [for lithium, Ar = 7] [for carbon Ar = 12 for hydrogen, Ar = 1 for oxygen Ar = 16] mass = g

Your answer

1 mark

(c)(i)

The teacher then adds a small piece of potassium to water.

Give one observation seen with potassium that is not seen with lithium.

Your answer

3 marks

(c)(ii)

Explain why potassium is more reactive than lithium. Refer to atomic structure in your answer.

Your answer

How did you do?/ 11

513 marks

1 mark

(a)(i)

A student does some titrations to find the volume of dilute nitric acid needed to exactly neutralise 25.0 cm³ of sodium hydroxide solution. This is the student’s method. Step 1 add 25.0 cm³ of sodium hydroxide solution to a conical flask Step 2 add three drops of methyl orange indicator Step 3 fill a burette with the acid Step 4 add acid from the burette until the indicator changes colour Step 5 record the volume of acid added

Give the name of the apparatus that the student should use to measure the volume of sodium hydroxide solution in step 1.

apparatus — official paper figure (qp.pdf p.12) (same figure as asset_5_a_apparatus_stem)

Your answer

1 mark

(a)(ii)

Give the colour change seen in step 4.

Your answer

1 mark

(a)(iii)

Give a reason why the student does not use universal indicator in this titration.

Your answer

2 marks

(b)(i)

The student completes a rough titration and four accurate titrations. The diagram shows the burette readings from the rough titration. Start End 2 23 3 24 4 25 The table shows the student’s results

Complete the table by adding the results from the rough titration. Record the volumes to the nearest 0.05 cm³

table — official paper figure (qp.pdf p.13) (same figure as asset_5_b_table_stem)

Your answer

3 marks

(b)(ii)

Concordant results are results within 0.20 cm³ of each other. Use the concordant results from the table to calculate the mean volume of acid added. mean volume of acid = cm³

table — official paper figure (qp.pdf p.13) (same figure as asset_5_b_table_stem)

Your answer

5 marks

(c)

This is the equation for the reaction between dilute nitric acid and sodium hydroxide solution. HNO₃(aq) + NaOH(aq) → NaNO₃(aq) + H₂O(l) After the titration, the student knows the volume of acid needed to neutralise 25.0 cm³ of the sodium hydroxide solution. Sodium nitrate decomposes at high temperatures. Describe how the student could obtain pure, dry crystals of sodium nitrate from dilute nitric acid and sodium hydroxide solution.

Your answer

How did you do?/ 13

613 marks

4 marks

(a)

This question is about crude oil.

Describe how crude oil is separated into fractions by fractional distillation.

Your answer

2 marks

(b)(i)

Some of the long-chain alkanes obtained from fractional distillation are cracked, producing shorter-chain alkanes and ethene.

Give the conditions necessary for cracking to occur.

Your answer

2 marks

(b)(ii)

Explain why shorter-chain alkanes are more useful than longer-chain alkanes.

Your answer

3 marks

(b)(iii)

Ethene reacts with bromine. The equation shows the displayed formulae of the reactants and product. H H H H C C + Br Br → H C C H H H Br Br The table shows some bond energies. Bond Bond energy in kJ/mol C C 612 C C 348 C H 414 Br Br 193 C Br 276 Show that the molar enthalpy change, ΔH, for this reaction is about –100 kJ/mol. ΔH = kJ/mol

table — official paper figure (qp.pdf p.16)

Your answer

2 marks

(b)(iv)

Explain why the reaction between ethene and bromine is exothermic. Refer to bond energies in your answer.

Your answer

How did you do?/ 13

712 marks

1 mark

(a)(i)

This question is about alcohols and carboxylic acids.

These are the structural formulae of alcohol A and carboxylic acid B. Alcohol A CH₃CH₂CH₂OH Carboxylic acid B CH₃(CH₂)nCOOH

Name alcohol A.

Your answer

1 mark

(a)(ii)

Draw the displayed formula of alcohol A.

Your answer

3 marks

(a)(iii)

Carboxylic acid B has a chain of carbon atoms with no branches. The number of CH₂ units is represented by the letter n. Calculate the value of n. [for carboxylic acid B, Mr = 242] n =

Your answer

1 mark

(a)(iv)

Alcohol A and carboxylic acid B react together to form an ester. Give the other product of the reaction.

Your answer

4 marks

(b)(i)

These are the structural formulae of dicarboxylic acid C and diol D. Dicarboxylic acid C HOOCCH₂CH₂COOH Diol D HOCH₂CH₂OH

This is the equation for the reaction between dicarboxylic acid C and sodium hydroxide solution. HOOCCH₂CH₂COOH + 2NaOH → NaOOCH₂CH₂COONa + 2H₂O 25.0 cm³ of 0.150 mol/dm³ sodium hydroxide solution is completely neutralised by 17.5 cm³ of a solution of dicarboxylic acid C. Calculate the concentration, in mol/dm³, of the solution of dicarboxylic acid C. Give your answer to three significant figures. concentration = mol/dm³

Your answer

2 marks

(b)(ii)

Dicarboxylic acid C and diol D react to form a polyester. Draw the displayed formula of the repeat unit of this polyester.

Your answer

How did you do?/ 12

Species

Number of protons

Number of neutrons

Number of electrons

513 marks

1 mark

(a)(i)

Give the name of the apparatus that the student should use to measure the volume of sodium hydroxide solution in step 1.

apparatus — official paper figure (qp.pdf p.12) (same figure as asset_5_a_apparatus_stem)

Your answer

1 mark

(a)(ii)

Give the colour change seen in step 4.

Your answer

1 mark

(a)(iii)

Give a reason why the student does not use universal indicator in this titration.

Your answer

2 marks

(b)(i)

The student completes a rough titration and four accurate titrations. The diagram shows the burette readings from the rough titration. Start End 2 23 3 24 4 25 The table shows the student’s results

Complete the table by adding the results from the rough titration. Record the volumes to the nearest 0.05 cm³

table — official paper figure (qp.pdf p.13) (same figure as asset_5_b_table_stem)

Your answer

3 marks

(b)(ii)

Concordant results are results within 0.20 cm³ of each other. Use the concordant results from the table to calculate the mean volume of acid added. mean volume of acid = cm³

table — official paper figure (qp.pdf p.13) (same figure as asset_5_b_table_stem)

Your answer

5 marks

(c)

Your answer

How did you do?/ 13