0620 Chemistry November 2025 Question Paper 61

1 Hot concentrated hydrochloric acid reacts with solid manganese(IV) oxide to make chlorine gas.

Chlorine gas is toxic and more dense than air. Concentrated hydrochloric acid is corrosive.

Fig. 1.1 shows the apparatus used to make and collect a sample of chlorine gas.

There is one error in the way the apparatus has been set up in Fig. 1.1. X HEAT Y Fig. 1.1

(a) Name the item of apparatus labelled X in Fig. 1.1 [1]

(b) Identify the substance labelled Y in Fig. 1.1 [1]

(c) Name an item of apparatus that can be used to heat X in Fig. 1.1 [1]

(d) There is one error in the way the apparatus has been set up.

Describe a change that needs to be made to the apparatus in Fig. 1.1 to correct this error [1]

(e) Explain why this experiment should be carried out in a fume cupboard [1]

[Total: 5] , ,

2 A student investigates the reaction between dilute hydrochloric acid and aqueous sodium hydroxide.

The student does five experiments.

Experiment 1 • Fill a burette with aqueous sodium hydroxide. • Run some of the aqueous sodium hydroxide out of the burette so that the level of the aqueous sodium hydroxide is on the burette scale. • Record the initial burette reading. • Use a volumetric pipette to add 25.0 cm3 of dilute hydrochloric acid to a conical flask. • Stand the conical flask on a white tile. • Add five drops of thymolphthalein indicator to the conical flask. • Slowly add aqueous sodium hydroxide from the burette to the conical flask, while swirling the flask, until the solution just changes colour. This is the end-point. • Record the final burette reading.

Experiment 2 • Empty the conical flask and rinse it with distilled water. • Refill the burette with aqueous sodium hydroxide. • Run some of the aqueous sodium hydroxide out of the burette so that the level of the aqueous sodium hydroxide is on the burette scale. • Record the initial burette reading. • Use the volumetric pipette to add 25.0 cm3 of dilute hydrochloric acid to the conical flask. • Add 0.25 g of sodium hydrogencarbonate to the conical flask and swirl the flask. • Stand the conical flask on the white tile. • Add five drops of thymolphthalein indicator to the conical flask. • Slowly add aqueous sodium hydroxide from the burette to the conical flask, while swirling the flask, until the solution just changes colour. This is the end-point. • Record the final burette reading.

Experiment 3 • Repeat Experiment 2 using 0.50 g of sodium hydrogencarbonate instead of 0.25 g.

Experiment 4 • Repeat Experiment 2 using 1.00 g of sodium hydrogencarbonate instead of 0.25 g.

Experiment 5 • Repeat Experiment 2 using 1.50 g of sodium hydrogencarbonate instead of 0.25 g. , ,

(a) Use the information in the descriptions of Experiments 1 to 5 and the burette diagrams in Fig. 2.1 and Fig. 2.2 to complete Table 2.1. Experiment 1 Experiment 2 initial burette reading final burette reading 2 1 0 47 46 45 initial burette reading final burette reading 2 1 0 42 41 40

Fig. 2.1 Fig. 2.2 Table 2.1 Experiment 1 Experiment 2 Experiment 3 Experiment 4 Experiment 5 volume of dilute hydrochloric acid / cm3 mass of sodium hydrogencarbonate / g 0.00 0.25 0.50 1.00 1.50 final burette reading / cm3 36.0 24.1 13.5 initial burette reading / cm3 1.4 0.3 0.5 volume of aqueous sodium hydroxide added to reach the end-point / cm3 13.0

[5] , ,

(b) Complete a suitable scale on the y-axis and plot the results from Experiments 1 to 5 in Table 2.1 on Fig. 2.3. Draw a straight line of best fit. 0.00 0 0.50 1.00 1.50 mass of sodium hydrogencarbonate / g volume of aqueous sodium hydroxide added to reach the end-point / cm3 2.00 2.50 Fig. 2.3

[4]

(c) The sodium hydrogencarbonate added in Experiments 2 to 5 neutralises some of the dilute hydrochloric acid in the conical flask. The sodium hydroxide used in the titration neutralises the remaining dilute hydrochloric acid.

Extrapolate the line on your graph in Fig. 2.3 and deduce the mass of sodium hydrogencarbonate needed to neutralise all of the dilute hydrochloric acid in the conical flask.

Show clearly on Fig. 2.3 how you worked out your answer.

mass of sodium hydrogencarbonate = [3] , ,

(d) (i) Explain why a volumetric pipette is used rather than a measuring cylinder to measure the volume of dilute hydrochloric acid used in each experiment [1]

(ii) Explain why it is not possible to use a volumetric pipette instead of the burette to measure the volume of aqueous sodium hydroxide added in each experiment [1]

(e) The conical flask is placed on a white tile to make the colour change of the indicator at the end-point more visible.

Explain why universal indicator is not a suitable indicator for this titration [2]

(f) Draw a line on Fig. 2.3 to show the results you would expect if the investigation was repeated using aqueous sodium hydroxide with twice the concentration.

Label your line F. [2]

[Total: 18] , ,

3 A student tests two solids: solid J and solid K.

Tests on solid J

Solid J is lithium chloride.

Record the expected observations.

(a) The student carries out a flame test on solid J.

(i) State the colour the Bunsen burner flame becomes during the flame test [1]

(ii) The student uses a roaring Bunsen burner flame to carry out the flame test.

State why a yellow Bunsen burner flame is not suitable for a flame test [1]

(b) The student dissolves the remaining solid J in distilled water to form solution J.

The student divides solution J into two portions.

(i) To the first portion of solution J, the student adds about 1 cm3 of dilute nitric acid followed by a few drops of aqueous silver nitrate. observations [1]

(ii) To the second portion of solution J, the student adds aqueous sodium hydroxide until it is in excess. observations [1] , ,

Tests on solid K

Table 3.1 shows the tests and the student’s observations for solid K.

Table 3.1 tests observations test 1 Heat about half of solid K in a boiling tube until there is no further change. condensation forms at the top of the boiling tube Hold anhydrous cobalt(II) chloride paper at the mouth of the boiling tube. the anhydrous cobalt(II) chloride paper changes colour from blue to pink test 2 The remaining solid K is dissolved in distilled water to form solution K. Solution K is divided into three portions. To the first portion of solution K, add aqueous ammonia dropwise and then in excess. a green precipitate forms the precipitate remains when excess aqueous ammonia is added test 3 To the second portion of solution K, add 1 cm3 of dilute nitric acid followed by a few drops of aqueous barium nitrate. a white precipitate forms test 4 To the third portion of solution K, add 3 cm3 of aqueous sodium carbonate. effervescence is seen and a green precipitate forms Test any gas given off. the gas turns limewater milky

(c) State the conclusion that can be made from the observations in test 1 [1]

(d) Two different cations can give the observations in test 2.

(i) Identify the two possible cations that the observations in test 2 show could be in solid K [2] , ,

(ii) Describe an additional test that can be carried out on solution K to confirm which of the two cations you have identified in (d)(i) is in solid K.

Explain how the result of this test shows which of these two cations is in solid K. test explanation [2]

(e) Identify the gas given off in test 4 [1]

(f) Identify the anion in solid K [1]

[Total: 11] , ,