Experimental Techniques (Cambridge (CIE) IGCSE Chemistry)

Exam Questions

5 hours44 questions
16 marks

The diagram shows two bottles of liquid oven cleaner. 

oven-cleaner

The oven cleaners contain sodium hydroxide solution. Plan an investigation to show which oven cleaner contains the highest concentration of sodium hydroxide. 

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2a1 mark

The following paragraph was taken from a student’s notebook.

To make potassium chloride

25.0 cm3 of aqueous potassium hydroxide were placed in a flask and a few drops of indicator were added. Dilute hydrochloric acid was added to the flask until the indicator changed colour. The volume of acid used was 19.0 cm3.

What piece of apparatus should be used to measure the aqueous potassium hydroxide? 

2b3 marks

i) Name a suitable indicator that could be used.

[1]

ii) The indicator would change from ........................... to ................................

[2]

2c2 marks

Which solution was more concentrated? Explain your answer.

2d3 marks

How could pure crystals of potassium chloride be obtained from this experiment?

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3a2 marks

Sulfur dioxide gas is denser than air and soluble in water. A sample of sulfur dioxide can be prepared by adding dilute hydrochloric acid to sodium sulfite and warming the mixture. Study the diagram of the apparatus used.  

12-1-q3a

Fill in the boxes to show the chemicals used.

3b1 mark

Show by using an arrow, on the diagram, where heat is applied.

3c2 marks

Identify two mistakes in the diagram. 

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4a1 mark

Ammonia is produced when aqueous sodium hydroxide is warmed with ammonium sulfate. Ammonia is less dense than air and very soluble in water. The apparatus below was used to prepare a sample of dry ammonia gas.

Name substance C.

4b1 mark

Name substance D.

4c1 mark

What necessary piece of equipment is missing in the diagram?

4d1 mark

Suggest why concentrated sulfuric acid should not be used to dry ammonia.

4e4 marks

There are two other mistakes in the apparatus shown in the diagram. Identify and explain these mistakes.

mistake 1 ..........................................................................................................
explanation ..........................................................................................................

mistake 2 ..........................................................................................................
explanation ..........................................................................................................

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5a
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4 marks

A student investigated the reaction between aqueous sodium carbonate and two different solutions of dilute hydrochloric acid, A and B.

The reaction is:

Na2CO3 (aq) + 2HCl (aq) → 2NaCl (aq) + H2O (l) + CO2 (g)

Three experiments were carried out.

Experiment 1

Using a measuring cylinder, 25 cm3 of aqueous sodium carbonate were poured into a conical flask.

Thymolphthalein indicator was added to the conical flask. A burette was filled up to the 0.0 cm3 mark with solution A. Dilute hydrochloric acid A was added to the flask, until the solution just changed colour. Use the burette diagram to record the reading in the table.

experiment-1-final-reading

Experiment 2

Experiment 1 was repeated using methyl orange indicator instead of thymolphthalein.

Methyl orange is red-orange in acidic solutions and yellow in alkaline solutions. Use the burette diagrams to record the readings in the table and complete the table. 

experiment-2-initial-and-final-reading

 

 experiment 1 

experiment 2

 final burette reading / cm3

 

 

 initial burette reading / cm3

 

 

 difference / cm3

 

 

5b1 mark

What colour change was observed in the flask in experiment 2?  

from .......................................... to ........................................ 

5c
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2 marks

Experiment 3

Experiment 1 was repeated using solution B of acid instead of solution A. Use the burette diagrams to record the readings in the table and complete the table.

experiment-3-intial-and-final-reading

 

experiment 3

 final burette reading / cm3

 

 initial burette reading / cm3

 

 difference / cm3

 

5d1 mark

Suggest one observation, other than colour change, that is made when hydrochloric acid is added to sodium carbonate.

5e1 mark

Complete the sentence below. Experiment .......... needed the largest volume of hydrochloric acid to change the colour of the indicator.

5f1 mark

What would be a more accurate method of measuring the volume of the aqueous sodium carbonate?

5g2 marks

What would be the effect on the results, if any, if the solutions of sodium carbonate were warmed before adding the hydrochloric acid? Give a reason for your answer.

effect on results ............................................................................................... reason ...............................................................................................

5h
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2 marks

i) Determine the ratio of volumes of dilute hydrochloric acid used in experiments 1 and 3.

[1]

ii) Use your answer to (h)(i) to deduce how the concentration of solution A differs from that of solution B.

 [1]

5i3 marks

Suggest a different method, using standard laboratory chemicals, to determine which of the solutions of dilute hydrochloric acid, A or B, is more concentrated.

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6a
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5 marks

A student investigated the reaction between sodium thiosulfate and potassium iodate.

Two experiments were carried out.

Experiment 1

A burette was filled up to the 0.0 cm3 mark with sodium thiosulfate solution. By using a measuring cylinder, 20 cm3 of solution A of potassium iodate was placed into a conical flask. Dilute sulfuric acid and potassium iodide were also added to the flask. The flask was shaken to mix the contents and produce a red solution of iodine.

The sodium thiosulfate solution was added to the flask. When the contents of the flask were yellow, 1 cm3 of starch solution was added to the flask. Addition of sodium thiosulfate to the flask was continued until the solution turned colourless.

Use the burette diagram to record the final volume in the table and complete the column in the table of results.

titre-39-2

   Experiment 2

   Experiment 1 was repeated using a different solution of potassium iodate, solution B.

   Use the burette diagrams to record the volumes and complete the table.

initial-titre-8-1
final-titre-28-7

   Table of results

   Burette readings / cm3 

 

Experiment 1

Experiment 2

final reading

 

 

initial reading

0.0

8.1

difference

 

 

   Suggest why the starch was used.

6b4 marks

i) In which experiment was the greatest volume of sodium thiosulfate solution used?

 [1]

 ii) Compare the volumes of sodium thiosulfate solution used in Experiments 1 and 2.

 [1]

 iii) Suggest an explanation for the difference in the volumes.

 [2]

6c
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2 marks

Predict the volume of sodium thiosulfate solution which would be needed to react completely with 10cm3 of solution B.

6d2 marks

Explain one change that could be made to the experimental method to obtain more accurate results, without changing the apparatus.

change ....................................................................................................

explanation ....................................................................................................

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7a1 mark

A student reacted dry ammonia gas with hot copper(II) oxide.

The apparatus used is shown below.

The equation for the reaction is

2NH3 + 3CuO → 3Cu + N2 + 3H2O

1-1q2-diag

Indicate with an arrow where the heat is applied. 

7b2 marks

The colour of the copper(II) oxide would change from ............................... to ...............................

7c2 marks

Draw a labelled diagram to show how liquid water could be obtained from the water vapour produced.

7d1 mark

Suggest the effect of nitrogen on a lighted splint.

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8a2 marks

A student investigated the reaction between two different solutions of dilute hydrochloric acid, A and B, and solution C which is alkaline.

Two experiments were carried out

Experiment 1

A burette was filled with solution A of dilute hydrochloric acid to the 0.0 cm3 mark. Using a measuring cylinder, 20 cm3 of solution C was poured into a conical flask. A few drops of methyl orange were added to the flask.

Solution A was added to the flask, with shaking, until the mixture just changed colour. Use the burette diagram to record the burette reading in the table and complete the table.

XwZN6J_N_12-1-q9a

 

burette readings

final volume / cm3

 

initial volume / cm3

 

difference / cm3

 

8b2 marks

Experiment 2

The burette was emptied and rinsed, first with distilled water, and then with a little of solution B. The burette was filled with solution B of dilute hydrochloric acid to the 0.0 cm3 mark.

Experiment 1 was repeated using solution B.

Use the burette diagram to record the burette reading in the table and complete the table.

12-1-q9b

 

burette readings

final volume / cm3

 

initial volume / cm3

 

difference / cm3

 

8c2 marks

i) What type of chemical reaction takes place when hydrochloric acid reacts with alkaline solutions?

[1]

ii) Why is methyl orange added to the flask?

[1]

8d2 marks

Why was the burette rinsed, first with distilled water and then with solution B, before starting Experiment 2?

8e4 marks

i) In which experiment was the greater volume of dilute hydrochloric acid used?

[1]

ii) Compare the volumes of dilute hydrochloric acid used in Experiments 1 and 2.

[1]

iii) Suggest, in terms of the concentration of solutions A and B, an explanation for the difference in volumes used. 

[2]

8f2 marks

If Experiment 2 was repeated using 10 cm3 of solution C, what volume of dilute hydrochloric acid would be used? Explain your answer. 

8g2 marks

Give one advantage and one disadvantage of using a measuring cylinder for solution C.

8h4 marks

Describe a method other than titration, using a different reactant, that could be used to compare the concentrations of the two solutions of dilute hydrochloric acid, A and B.

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9a
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4 marks

A student investigated the redox reaction between potassium iodate(V) and iodide ions.

Two experiments were carried out.

Experiment 1

A burette was filled up to the 0.0 cm3 mark with the solution A of sodium thiosulphate. By using a measuring cylinder, a 10 cm3 sample of the solution B of potassium iodate(V) was added into a conical flask. A 10 cm3 sample of dilute sulfuric acid was added to the flask followed by 20 cm3 of aqueous potassium iodide.

Solution A was added slowly to the flask until there was a pale yellow colour in the contents of the flask. Starch solution was then added into the flask and the colour changed to blue black. Solution A was added to the flask until the colour just disappeared.

redox-final-burette-reading

Experiment 2

Experiment 1 was repeated using solution C of potassium iodate(V) instead of solution B.

redox-initial-and-final-burette-reading

Use the burette diagrams for experiment 1 and 2 to record the volumes in the table and complete the table.

 Burette readings / cm3

Experiment 1 

Experiment 2

 Final reading

 

 

 Initial reading

0.0

 

 Difference

 

 

9b2 marks

The reaction of the mixture of potassium iodate(V), sulfuric acid and potassium iodide in the flask produces iodine. Sodium thiosulfate then reacts with the iodine.

i) In which Experiment was the greatest volume of aqueous sodium thiosulfate used?

[1]

ii) Compare the volumes of sodium thiosulfate used in Experiments 1 and 2.

[1]

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10a2 marks

A student investigated the reaction between aqueous sodium hydroxide and acid K.

Two experiments were carried out. 

Experiment 1

Using a measuring cylinder, 25 cm3 of acid K was poured into a conical flask. Phenolphthalein indicator was added to the flask. A burette was filled with aqueous sodium hydroxide to the 0.0 cm3 mark. Aqueous sodium hydroxide was added from the burette to the flask and the mixture shaken until the solution showed a permanent colour change.

The final volume was measured. Use the burette diagram to record the final volume in the table and complete the table.

12-1-q11a

 

burette readings

final volume / cm3

 

initial volume / cm3

 

difference / cm3

 

10b2 marks

Experiment 2

The solution was poured away and the conical flask rinsed.

Using a measuring cylinder, 50 cm3 of acid K was poured into the conical flask. 0.3 g of powdered calcium carbonate was added to the flask and the flask shaken until no further reaction was observed.

Phenolphthalein was added to the mixture in the flask.

A burette was filled with the same aqueous sodium hydroxide and the initial volume measured. Aqueous sodium hydroxide was added from the burette to the flask and the mixture shaken until the solution showed a permanent colour change.

Use the burette diagrams to record the initial and final volumes in the table and complete the table.

12-1-q11b

 

burette readings

final volume / cm3

 

initial volume / cm3

 

difference / cm3

 

10c1 mark

What type of chemical reaction occurred when acid K reacted with sodium hydroxide?

10d2 marks

If Experiment 1 were repeated using 50 cm3 of acid K, what volume of sodium hydroxide would be required to change the colour of the indicator?

10e
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5 marks

i) What were the effects of adding 0.3 g of powdered calcium carbonate to acid K

[2]

ii) Use your answer in (d) to work out the difference between the volume of sodium hydroxide needed to completely react with 50 cm3 of acid K and the volume of sodium hydroxide used in Experiment 2.

[2]

iii) Estimate the mass of calcium carbonate that would be needed to be added to 50 cm3 of acid K to require 0.0 cm3 of sodium hydroxide.

[1]

10f2 marks

What would be the effect on the results if the solutions of acid K were warmed before adding the sodium hydroxide? Give a reason for your answer.

10g4 marks

Suggest the advantage, if any, of 

i) using a pipette to measure the volume of acid K.

[2]

ii) using a polystyrene cup instead of a flask.

[2]

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11a2 marks

A student investigated the reaction between two different solutions of deep purple potassium manganate(VII), A and B, and an acidic solution of hydrogen peroxide.

Three experiments were carried out.

Experiment 1

A burette was filled with the solution A of potassium manganate(VII) up to the 0.0 cm3 mark. Using a measuring cylinder, 25 cm3 of colourless hydrogen peroxide solution was poured into the conical flask.

The potassium manganate(VII) solution A was added slowly to the flask, and shaken to mix thoroughly. Addition of potassium manganate(VII) solution was continued until there was a permanent pink colour in the contents of the flask.

Use the burette diagram to record the volume in the table of results and complete the column. 

12-1-q12a

 

experiment 1

final reading / cm3

 

initial reading / cm3

 

difference cm3

 

11b
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2 marks

Experiment 2

Experiment 1 was repeated using the solution B of potassium manganate(VII) instead of solution A.

Use the burette diagrams to record the volumes in the table of results and complete the table. 

12-1-q12b

 

experiment 2

final reading / cm3

 

initial reading / cm3

 

difference / cm3

 

11c1 mark

Experiment 3 To a little of the hydrogen peroxide solution in a test-tube, manganese(IV) oxide was added. Rapid effervescence was observed and a glowing splint relit.

Identify the gas given off in Experiment 3.

11d2 marks

i) What colour change was observed when potassium manganate(VII) solution was added to the flask?

from ..................................................... to ..................................................... 

[1]

ii) Why was an indicator not added to the flask?

[1]

11e4 marks

i) In which experiment was the greatest volume of potassium manganate(VII) solution used?

[1]

ii) Compare the volumes of potassium manganate(VII) used in Experiments 1 and 2.

[1]

iii) Suggest an explanation for the difference in volumes.

[2]

11f
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3 marks

If Experiment 2 was repeated using 12.5 cm3 of the hydrogen peroxide solution, what volume of potassium manganate(VII) solution would be needed to react completely? Explain your answer.

11g2 marks

Give one advantage and one disadvantage of using a measuring cylinder for the hydrogen peroxide solution.

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12a4 marks

Look at the diagrams of common laboratory apparatus.

lab-equipemnt-question

Complete the empty boxes to identify the pieces of apparatus labelled.

12b1 mark

What name is given to the separation method in C?

12c1 mark

Which apparatus would be most suitable to obtain crystals from an aqueous solution of copper(II) sulphate?

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13a2 marks

Hydrogen chloride gas is strong-smelling, denser than air and soluble in water. A sample of hydrogen chloride gas can be prepared by adding concentrated sulfuric acid to sodium chloride. Study the diagram of the apparatus used.

gas-collection-prac-incorrect

Fill in the boxes to show the chemicals used.

13b4 marks

Identify and explain two mistakes in the diagram.

 Mistake 1 ....................................................................................................

[2]

Mistake 2 ....................................................................................................

[2]

13c1 mark

State one precaution that should be taken when carrying out this experiment.

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14a4 marks

A student investigated an aqueous solution of calcium hydroxide and water.

Two experiments were carried out.

Experiment 1

By using a measuring cylinder 25 cm3 of the aqueous solution of calcium hydroxide was placed in a flask. Phenolphthalein indicator was added to the flask. A burette was filled to the 0.0cm3 mark with solution M of hydrochloric acid.

Solution M was added slowly to the flask until the colour just disappeared.

Use the burette diagram to record the volume in the table and complete the column.

 

burette-10-6

 

Experiment 2  

Experiment 1 was repeated using a different solution, N, of hydrochloric acid.

Use the burette diagrams to record the volumes in the table and complete the table.

 

burette-14-9-and-36-1

 

Table of results

 

burette readings / cm3

Experiment 1

Experiment 2

final reading

 

 

initial reading 

0.0

 

difference

 

 

14b1 mark

What type of chemical reaction occurs when hydrochloric acid reacts with calcium hydroxide?

14c
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5 marks

i) In which experiment was the greater volume of hydrochloric acid used?

 [1]

 ii) Compare the volumes of acid used in Experiments 1 and 2.

 [2]

 iii) Suggest an explanation for the difference in volumes.

 [2]

14d
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3 marks

Predict the volume of hydrochloric acid M that would be needed to react completely if Experiment 1 was repeated with 50cm3 of calcium hydroxide solution?  

volume of solution ..................................................  

explanation ....................................................................................................

14e1 mark

Suggest one change you could make to the apparatus used in the experiments to obtain more accurate results.

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