DP IB Chemistry: SL

Topic Questions

Syllabus Edition

First teaching 2014

Last exams 2024

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11.2 Synoptic Data Handling & Graphical Skills

1a1 mark

Outline the difference between quantitative and qualitative data.

1b1 mark

A student uses a thermometer to measure the temperature of a beaker of water, before and after heating. The smallest thermometer division is 1.0 oC. The initial temperature of the water is 23.0 oC.

How should the temperature change be recorded?

1c2 marks
Explain how a student over-shooting the end point in a titration affects the final result of the titration calculation.
1d2 marks

This question is about precision....

i)
Explain what is meant by the term precision in recorded data. 
[1]
a)
Indented content here...
ii)
The table shows a set of titration results:
 
Initial burette reading/ + 0.05 cm3 0.00
Final burette reading/ + 0.05 cm3 23.40
Volume delivered/ cm3  

How should the volume delivered be recorded?

 [1]

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2a2 marks

Outline the difference between a random error and a systematic error.

2b2 marks

A student forgets to tare the balance while carrying out an experiment to find the empirical formula of magnesium oxide.


State what type of error this is, and deduce the impact on the student's mass readings.

2c1 mark
Explain how random errors may be reduced in an experiment.

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3a
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2 marks

A student carries out a thermal decomposition of copper(II) carbonate. The copper(II) carbonate is placed in a pre-weighed crucible and the crucible is weighed again when cool. The reaction that takes place is:

CuCO3 (s)  → CuO(s) + CO2 (g)

The results are recorded in the table.

  Mass/ + 0.01 g
Mass of empty crucible 38.52 g
Mass of crucible + copper(II) carbonate 46.73 g
Mass of crucible + copper(II) oxide 43.61 g
 

Calculate the mass of copper(II) oxide formed and determine the percentage uncertainty in the calculated mass.

3b
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3 marks

Determine the theoretical yield of copper(II) oxide in part a)

3c
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1 mark

Determine the percentage error in the experiment.

3d2 marks

The student forgets to turn the Bunsen burner, used to heat the crucible, to a blue flame. The yellow, sooty flame, soon coats the outside of the crucible with a black layer.

Identify the black layer and suggest whether the error will have a major or minor effect on their results.

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4a1 mark

Explain the difference between a dependent variable and independent variable on a graph.

4b1 mark

A student analyses a set of results from the determination of the empirical formula of magnesium oxide by burning magnesium ribbon.
They plot a graph on the following grid:

11-2-ib-sl-sq-easy-q4b

Identify the dependent and independent variables.

4c2 marks

The student plots the result an obtains the following graph.

11-2-ib-sl-sq-easy-q4c

Justify whether a best fit straight line on this graph can or cannot be considered.

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5a1 mark

The sketch graph below shows the variation of the mass of magnesium with the mass of oxygen, from the results of an empirical formula investigation.

11-2-ib-sl-sq-easy-q5a

Describe the relationship between the two variables.

5b2 marks

Using the graph in part a), show how the gradient maybe calculated and explain it's significance for magnesium and oxygen.

5c
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2 marks

The rate of reaction between magnesium and hydrochloric acid was investigated. The concentration of acid was varied and the results plotted on a graph.

11-2-ib-sl-sq-easy-q5c

Draw a best fit line and calculate the gradient.

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1a2 marks

A student prepared some phenyl benzoate by reacting phenol with benzoyl chloride in alkaline conditions. The equation for the reaction is:

11-2-ib-sl-sq-hard-q1a-phenyl-benzoate-prep

The table shows the data recorded by the student:

Mass of phenol used 4.85  + 0.02 g
Mass of phenyl benzoate obtained 6.34  + 0.02 g

State the names of two functional groups found in the product

1b
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5 marks

Determine the following quantities from the data in part a):

i)
The amount, in mol, of phenol used

[2]

ii)
The theoretical yield, in g, of phenyl benzoate 

[2]

iii)
The percentage yield of phenyl benzoate

[1]

1c
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2 marks

State the number of significant figures associated with the mass of phenyl benzoate obtained and calculate the percentage uncertainty associated with this mass.

1d1 mark

Another student repeated the experiment and obtained an experimental yield of 145%. 

The teacher checked the student's calculations and found no errors.
Suggest an explanation for this result.

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2a1 mark

A student titrated hydrochloric acid solution against 50.0 cm3 of 0.950 mol dm-3 sodium hydroxide solution to determine is concentration.

After each addition of acid the temperature was measured to the nearest 0.5 oC and recorded and plotted on a graph:

11-2-ib-sl-sq-hard-q2a-question

What should the labels be on each axis?

2b2 marks

Use the graph to:

i)
Estimate the initial temperature of the solution.

[1]

ii)
Determine the maximum temperature reached in the experiment
[1]
2c
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2 marks

Use the values obtained in part b) to determine the temperature change and percentage uncertainty in the calculated value.

2d
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1 mark

Determine the concentration of the acid used in the experiment.

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3a
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3 marks

A student investigated the diffusion of ammonia and hydrogen chloride gases in a 1.00 m glass tube. She placed cotton wool plugs containing concentrated ammonia and hydrochloric acid at either end of the tube and sealed the ends with stoppers. 

11-2-q3h

Where the two gases meet a white smoke ring of ammonium chloride, NH4Cl, appears. The student recorded the time taken for the white smoke to appear and the distance travelled by each gas.

  1st trial 2nd trial 3rd trial
Total time elapsed /s 126  114  163 
Distance travelled by NH3 (g) / cm 72  68  75 
Distance travelled by HCl (g) / cm 28  32  25 

The rate of diffusion of a gas is proportional to the square root of the mass of its particles.

Calculate the mean rate of diffusion of ammonia and hydrogen chloride, expressing your answer to an appropriate number of significant figures.

3b
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3 marks

The rate of diffusion of a gas is proportional to the square root of its mass.

Rate space equals space fraction numerator 1 over denominator square root of M subscript r end root end fraction

When two gases, A and B, are compared the relative rates of diffusion are: 

Rate subscript straight A over Rate subscript straight B equals space fraction numerator square root of M subscript r subscript straight B end root over denominator square root of M subscript r subscript straight A end root end fraction

Determine the relative rate of diffusion of the ammonia and hydrogen chloride from their molar masses and from part a).

Comment on your result.

3c
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1 mark

Determine the percentage error in the experiment.

3d2 marks

The student cleans and dries the glass tube between each run of the experiment. If the glass tube is not completely dry, state what type of error can occur and what its impact on the results would be.

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4a1 mark

The graph below shows measurements of pressure and volume for a sample of air at constant temperature.

3NoeBlip_11-2-q4h

Draw a best fit line through the points.

4b1 mark

Deduce the relationship between pressure and volume in the sample of air.

4c4 marks

Given the average molar mass of air is 28.97 g mol-1, find the number of moles of air used in the experiment using the values at point X.

4d
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2 marks

Determine the percentage uncertainty in the measure data at point, X. 

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1a4 marks

Aluminium will react with copper(II) sulfate solution according to the following equation:

2Al (s) + 3CuSO4 (aq) "  3Cu (s) + Al2(SO4)3 (aq)

The reaction is quite slow at room temperature, but when chloride ions in the form of hydrochloric acid are added, the rate increases significantly. The chloride ions catalyse the reaction.

An experiment was carried out to determine the yield of the reaction. A student made a solution of aqueous copper(II) sulfate by dissolving 2.00 g of copper(II) sulfate pentahydrate, CuSO4.5H2O (Mr  249.72 g mol-1) in 10.0 mL of distilled water in a small beaker.

To this solution she added 0.25 g of aluminium foil followed by 2.0 mL of 6.0 mol dm-3 hydrochloric acid.

After the reaction was complete, she collected, dried, and weighed the copper that was produced.

She recorded the measurements in Table 1 below.

Table 1

 

Mass / ± 0.01 g

Initial mass of copper sulfate

2.00

Mass of aluminium foil used

0.25

Mass of empty beaker

42.18

Mass of beaker with dry copper

42.61

 

Use the data to show that the copper sulfate is the limiting reagent in the experiment and calculate the mass of aluminium in excess.

1b3 marks

Calculate the actual yield and the percentage yield of copper in the experiment.

1c2 marks

Determine the percentage uncertainty in the mass of copper produced, and the overall percentage error for the experiment.

1d2 marks

Discuss the impact on the percentage yield of copper from the following systematic errors:

i)
The copper collected is not fully dried out before the beaker is weighed.

ii)
The student misread the instructions and used 1.0 mL of hydrochloric acid. 

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2a3 marks

A student carried out a metal displacement reaction between zinc powder and copper(II) sulfate solution. The equation for the reaction is

Zn (s) + CuSO4 (aq) → ZnSO4 (aq) + Cu (s)

3.78 g of zinc powder was added to 50.0 cm3 of 0.250 moldm-3 copper(II) sulfate solution.

Determine the limiting reagent showing your working.

2b2 marks

The reaction between the zinc and copper sulfate was carried out in a polystyrene cup and the temperature change was measured using a temperature probe. The maximum temperature rise the student recorded was 8.5 oC. 

Using section 1 and 2 of the data booklet, calculate the enthalpy change, H, for the reaction, in kJ.

Assume that all the heat evolved was absorbed by the solution, and that the density and specific heat capacity of the copper(II) sulfate solution are the same as pure water.

2c2 marks

State two further assumptions made in the calculation of H.

2d4 marks

Using Figure 1, sketch a graph of the concentration of zinc sulfate, ZnSO4 (aq), versus time and show how the graph may be used to find the initial rate of reaction.

                                                                  Figure 111-2-ib-chemistry-sq-q2d-medium

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3a4 marks

The concentration of coloured metal ions in a solution can be determined by spectroscopic methods, such as colorimetry. A colorimeter is used to measure relative absorbance of a number of standard solutions and a calibration graph is drawn.

Table 1 shows the concentration of nickel(II) ions and the relative absorbance of light at 635 nm wavelength.

Table 1

Concentration of Ni(II) ions / moldm-3

Relative absorbance

1.0

0.890

0.8

0.717

0.5

0.450

0.3

0.270

0.1

0.089

 

Using Figure 1, draw a labelled a graph of concentration against relative absorbance and draw a line of best fit through the points.

Figure 1

11-2-ib-chemistry-sq-q3a-medium

3b3 marks

Identify the dependent and independent variables and use the graph in part (a) to determine the concentration of a solution of Ni(II) ions whose relative absorbance is 0.560. Show how you arrive at your answer.

3c4 marks

Use your graph from part (a) to answer the following questions.

i)
State the type of relationship shown between the variables. 

ii)
Determine the value of in the formula: y equals m x plus c.
 
iii)
Use the formula and your answer in (ii) to calculate the concentration of the Ni(II) ions when the relative absorbance in 0.560 and comment on your result compared to the value found graphically in part (b).
3d1 mark

The relationship between concentration and absorbance is only linear at low concentrations. Suggest a possible reason for this.

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4a3 marks

The Winkler method is a chemical technique used to measure the concentration of dissolved oxygen in water samples. The method involves treating the samples to convert the dissolved oxygen into iodine which is then titrated against standard sodium thiosulfate solution as shown below:

Step 1:             2Mn2+ (aq) + O2 (aq) + 4OH (aq) → 2MnO2 (s) + 2H2O (l)

Step 2:             MnO2 (s) + 2I (aq) + 4H+ (aq) → Mn2+ (aq) + I2 (aq) + 2H2O (l)

Step 3:             2S2O32− (aq) + I2 (aq) → 2I (aq) + S4O62− (aq)

A student wanted to check if the water in a fish tank was sufficiently oxygenated and analysed two 500 cm3 samples, five days apart.

The following results in Table 1 were obtained when the resulting iodine was titrated against 0.0120 moldm-3 Na2S2O3 (aq).

Table 1

Oxygen analysis in fish tank water on day 0

 Initial burette reading / cm3 + 0.1cm3

0.20

 Final burette reading / cm3 + 0.1cm3

26.0

 Titre / cm3

 

i)
Determine the reacting ratio by moles of S2O32− to O2, using the balanced equations in steps 1-3. 

ii)
Calculate the titre and determine the percentage uncertainty in the reading. 
4b3 marks

Determine the number of moles of oxygen in the 500 cm3 sample and hence the concentration in ppm.

4c2 marks

It is generally considered that dissolved oxygen levels of at least 4-5 ppm are sufficient for most aquatic life. The day 5 sample contained 5.03 × 10−5 moles of oxygen.

Discuss whether the student should be concerned about the oxygen levels in the fish tank over the 5-day period.

4d1 mark

Suggest a modification to the procedure which would make the result more reliable.

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5a4 marks

A student investigated the rate of decomposition of hydrogen peroxide, H2O2, at a temperature of 45 o The decomposition reaction occurs in the presence of a catalyst, MnO2.

 2 straight H subscript 2 straight O subscript 2 space left parenthesis aq right parenthesis space space rightwards arrow with space MnO subscript 2 on top space space space straight O subscript 2 space left parenthesis straight g right parenthesis space plus space 2 straight H subscript 2 straight O space left parenthesis straight l right parenthesis           

The results she obtained are shown in Table 1 below.

Table 1

Time / s

Concentration of H2O2 / moldm-3

Time / s

Concentration of H2O2 / moldm-3

0

0.200

120

0.068

20

0.155

140

0.063

40

0.124

160

0.058

60

0.102

180

0.055

80

0.085

200

0.052

100

0.075

 

 

 

Plot a graph on the axes below in Figure 1 and from it determine the rate of reaction after 60 s.

Figure 1

11-2-ib-chemistry-sq-q5a-medium

5b3 marks

On the same graph sketch the shape obtained if the student had carried out the same reaction at 60 oC. Explain the shape of the graph at 60 oC.

5c3 marks

The decomposition of hydrogen peroxide can be investigated by measuring the volume of oxygen given off using the apparatus shown in Figure 2.

Figure 2

11-2-ib-chemistry-sq-q5c-medium

i)
Explain why the volume of oxygen given off can be used as a measure of the concentration of hydrogen peroxide. 

ii)
Suggest one limitation of using the apparatus used in Figure 2.
iii)
Suggest an alternative method of measuring the rate of reaction.
5d2 marks

Two students decide to measure the rate of decomposition for H2O2 using the change in mass as oxygen escapes from the reaction container.

One student says that they should use a three decimal place rather than two decimal place balance because it will make their results more accurate. The second student disagrees and says it will make their results more precise, but not more accurate.

Which student is correct?

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