99 questions

Chemistry/Paper 3/Analysis, Conclusions and Evaluation

CAIEO-Level5070-o · Paper 3

Analysis, Conclusions and Evaluation

99 questions· page 1 of 10

Q32024 May/Jun·P316MMedium-HardPlanning Experiments and Investigations

You are not expected to do any experimental work for this question

Barium carbonate decomposes when heated. The word equation for the reaction is shown.

\text{barium carbonate} \rightarrow \text{barium oxide} + \text{carbon dioxide}

Plan an experiment to determine the percentage loss in mass when barium carbonate is heated.

Your plan must include the use of common laboratory apparatus and a sample of barium carbonate. No other chemicals should be used.

Your plan must include:

the apparatus needed
the method to use and the measurements to take
procedures to ensure that the percentage determined is as accurate as possible
how the measurements are used to determine the percentage loss in mass.

You may draw a diagram to help answer the question.

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Q32024 Oct/Nov·P316MMediumExperimental Contexts

You are not expected to do any practical work for this question.

Argentan is an alloy containing only zinc, nickel and copper.

Zinc and nickel both react with dilute hydrochloric acid. Copper does not react with dilute hydrochloric acid.

Plan an investigation to find the percentage by mass of copper in a powdered sample of argentan.

Your plan must include the use of common laboratory apparatus, argentan and hydrochloric acid. No other chemicals should be used.

Your plan must include:

the apparatus needed
the method to use and the measurements to take
procedures to ensure that the percentage determined is as accurate as possible
how the measurements are used to determine the percentage by mass of copper in the sample.

You may draw a diagram to help answer the question.

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Q12021 May/Jun·P327 partsMediumExperimental Contexts

(a)

Put P into the burette.

Pipette $25.0\text{ cm}^3$ of Q into a flask and titrate with P using three drops of thymolphthalein as the indicator.

The end-point is when the solution remains colourless for 30 seconds.

Record your results in the table.

Repeat the titration as many times as necessary to achieve consistent results.

Results

titration number	1	2
final burette reading / $\text{cm}^3$
initial burette reading / $\text{cm}^3$
volume of P used / $\text{cm}^3$
best titration results $(\checkmark)$

Summary

Tick $(\checkmark)$ the best titration results.

Use the best titration results to calculate the average volume of P required.

______ $\text{cm}^3$

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(b)

Q is $0.100\text{ mol / dm}^3\text{ KOH(aq)}$ .

Calculate the number of moles of $\text{KOH}$ in $25.0\text{ cm}^3$ of Q.

______ $\text{mol}$

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(c)

Use your answer from (b) to calculate the number of moles of malic acid, $\text{H}_2\text{C}_4\text{H}_4\text{O}_5$ , in the average volume of P used.

2\text{KOH} + \text{H}_2\text{C}_4\text{H}_4\text{O}_5 \rightarrow \text{K}_2\text{C}_4\text{H}_4\text{O}_5 + 2\text{H}_2\text{O}

______ $\text{mol}$

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(d)

Use your answer from (c) to calculate the concentration of malic acid in P.

Give your answer to three significant figures.

______ $\text{mol / dm}^3$

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(e)

The average concentration of malic acid in apple juice is $4.5\text{ g / dm}^3$ .

Calculate the average concentration of malic acid, $\text{H}_2\text{C}_4\text{H}_4\text{O}_5$ , in apple juice in $\text{mol / dm}^3$ .

[ $A_r$ : H, 1; C, 12; O, 16]

______ $\text{mol / dm}^3$

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(f)

Use your answers from (d) and (e) to calculate the average volume of apple juice which contains the same mass of malic acid as $200\text{ cm}^3$ of P.

Give your answer in $\text{dm}^3$ .

______ $\text{dm}^3$

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(g)

Suggest why accurate titration of apple juice with $\text{KOH}$ usually produces an average value higher than your answer from (e).

______

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Q22018 May/Jun·P3123MMediumQualitative Analysis

You are provided with solution $\mathbf{R}$ and solid $\mathbf{S}$ .

Carry out the following tests and record your observations in the table.
You should test and name any gas evolved.

test no.	test	observations
1	Test a sample of $\mathbf{R}$ with both red and blue litmus paper.
2	(a) To $1\text{ cm}$ depth of $\mathbf{R}$ in a test-tube, add an equal volume of aqueous barium nitrate. (b) To the mixture from (a), add dilute nitric acid.
3	To $2\text{ cm}$ depth of $\mathbf{R}$ in a test-tube, add a piece of magnesium ribbon.
4	Put $2\text{ cm}$ depth of $\mathbf{R}$ in a boiling tube and warm the liquid until it just begins to boil. To the hot $\mathbf{R}$ , add $\mathbf{S}$ , a small amount at a time, until no further reaction takes place. Filter the final mixture into a clean boiling tube. Retain the filtrate for tests 5 and 6.
5	To half of the filtrate from test 4 in a test-tube, add aqueous sodium hydroxide until no further change occurs.
6	To the other half of the filtrate from test 4 in a test-tube, add aqueous ammonia until no further change occurs.
7	Put a small amount of $\mathbf{S}$ into a hard glass test-tube and heat the solid. Retain the final solid for test 8.
8	(a) To $1\text{ cm}$ depth of aqueous hydrogen peroxide in a test-tube, add a little of the final solid from test 7. (b) To the mixture from (a), add an equal volume of aqueous ammonia.

[21]

(conclusions) ### Conclusions

Identify the compound present in $\mathbf{R}$ . ______

Identify compound $\mathbf{S}$ . ______

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Q22017 Oct/Nov·P3123MMediumQualitative Analysis

You are provided with two solutions, R and S.

(a) Carry out the following tests and record your observations in the table.

You should test and name any gas evolved.

test no.	test	observations with solution R	observations with solution S
1	(a) To $2\text{ cm}$ depth of the solution in a test-tube, add aqueous sodium hydroxide until a change is seen. (b) To the mixture from (a), add excess aqueous sodium hydroxide.
2	(a) To $2\text{ cm}$ depth of the solution in a test-tube, add aqueous ammonia until a change is seen. (b) To the mixture from (a), add excess aqueous ammonia. Keep the final mixture for use in (c). (c) To $1\text{ cm}$ depth of aqueous hydrogen peroxide in a boiling tube, add the final mixture from (b).
3	(a) To $1\text{ cm}$ depth of the solution in a test-tube, add an equal volume of dilute nitric acid. (b) Pour half of the mixture from (a) into a test-tube and add an equal volume of aqueous barium nitrate. (c) To the other half of the mixture from (a), add an equal volume of aqueous silver nitrate.

(b) ### Conclusions

Identify the compound in solution R.

The compound in solution R is ______ .

Identify the compound in solution S.

The compound in solution S is ______ .

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Q12017 Oct/Nov·P325 partsMedium-EasyObservations and Measurements

(a)

Put P into the burette.

Pipette a $25.0\text{ cm}^3$ (or $20.0\text{ cm}^3$ ) portion of Q into a flask and titrate with P, using the indicator provided.

Record your results in the table, repeating the titration as many times as you consider necessary to achieve consistent results.

Results

Burette readings

titration number	1	2
final reading / $\text{cm}^3$
initial reading / $\text{cm}^3$
volume of P used / $\text{cm}^3$
best titration results (✓)

Summary

Tick (✓) the best titration results.

Using the best titration results, the average volume of P required was ______ $\text{cm}^3$ .

Volume of Q used was ______ $\text{cm}^3$ .

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(b)

Q is $0.586\text{ mol / dm}^3$ sodium hydroxide.

Using your results from (a), calculate the concentration, in $\text{mol / dm}^3$ , of sulfuric acid in P. Give your answer to three significant figures.

2\text{NaOH} + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O}

concentration of sulfuric acid in P = ______ $\text{mol / dm}^3$

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(c)

Using your answer from (b), calculate the number of moles of sulfuric acid in $10.0\text{ cm}^3$ of concentrated sulfuric acid.

moles of sulfuric acid in $10.0\text{ cm}^3$ of concentrated sulfuric acid = ______

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(d)

Using your answer from (c), calculate the concentration, in $\text{mol / dm}^3$ , of concentrated sulfuric acid.

concentration of concentrated sulfuric acid = ______ $\text{mol / dm}^3$

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(e)

Using your answer from (d), calculate the mass, in $\text{g}$ , of sulfuric acid in $1\text{ dm}^3$ of concentrated sulfuric acid.
[The relative formula mass of sulfuric acid is 98.]

mass of sulfuric acid in $1\text{ dm}^3$ of concentrated sulfuric acid = ______ $\text{g}$

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Q22016 May/Jun·P3122MMedium-HardExperimental Contexts

You are provided with solid $\mathbf{R}$ and solution $\mathbf{S}$ .

Carry out the following tests and record your observations in the table. You should test and name any gas evolved.

test no.	test	observations
1	To $1\text{ cm}$ depth of aqueous iodine in a test-tube, add a small amount of $\mathbf{R}$ and mix.
2	Dissolve a small amount of $\mathbf{R}$ in $3\text{ cm}$ depth of distilled water in a test-tube. Divide this solution into two equal portions for use in tests 3 and 4.	no observation required
3	(a) To $1\text{ cm}$ depth of aqueous barium nitrate in a test-tube, add a few drops of the solution of $\mathbf{R}$ from test 2. (b) To the mixture from (a), add dilute nitric acid.
4	(a) To $1\text{ cm}$ depth of silver nitrate in a test-tube, add the solution of $\mathbf{R}$ from test 2 until a change occurs. (b) To the mixture from (a), add the remainder of the solution of $\mathbf{R}$ .
5	(a) To $1\text{ cm}$ depth of aqueous iron(III) chloride in a test-tube, add a small amount of $\mathbf{R}$ and mix well. (b) To the mixture from (a), add about the same volume of dilute sulfuric acid and mix well for about 10 seconds. (c) Add aqueous sodium hydroxide to the mixture from (b) until no further change is seen.
6	To $1\text{ cm}$ depth of $\mathbf{S}$ in a test-tube, add about the same volume of dilute sulfuric acid. To the mixture in the test-tube, add a small amount of $\mathbf{R}$ and mix well.
7	To $1\text{ cm}$ depth of $\mathbf{S}$ in a test-tube, add about the same volume of aqueous hydrogen peroxide.
8	(a) To $1\text{ cm}$ depth of aqueous potassium iodide in a test-tube, add about the same volume of dilute sulfuric acid. To the mixture, add a few drops of $\mathbf{S}$ . (b) To the mixture from (a), add a few drops of starch solution. (c) To the mixture from (b), add a small amount of $\mathbf{R}$ and mix well.
9	To $1\text{ cm}$ depth of $\mathbf{S}$ in a test-tube, add about the same volume of aqueous sodium hydroxide. To the mixture add a small amount of $\mathbf{R}$ , mix well and leave to stand.

[20]

Conclusions

In tests 1 and 5, $\mathbf{R}$ is acting as ______ .

In test 8, $\mathbf{S}$ is acting as ______ . [2]

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Q22016 May/Jun·P3222MMedium-HardObservations and Measurements

You are provided with solid R and solution S.

Carry out the following tests and record your observations in the table. You should test and name any gas evolved.

test no.	test	observations
1	To $1\text{ cm}$ depth of aqueous iodine in a test-tube, add a small amount of R and mix.
2	Dissolve a small amount of R in $3\text{ cm}$ depth of distilled water in a test-tube. Divide this solution into two equal portions for use in tests 3 and 4.	no observation required
3	(a) To $1\text{ cm}$ depth of aqueous barium nitrate in a test-tube, add a few drops of the solution of R from test 2. (b) To the mixture from (a), add dilute nitric acid.
4	(a) To $1\text{ cm}$ depth of silver nitrate in a test-tube, add the solution of R from test 2 until a change occurs. (b) To the mixture from (a), add the remainder of the solution of R.
5	(a) To $1\text{ cm}$ depth of aqueous iron(III) chloride in a test-tube, add a small amount of R and mix well. (b) To the mixture from (a), add about the same volume of dilute sulfuric acid and mix well for about 10 seconds. (c) Add aqueous sodium hydroxide to the mixture from (b) until no further change is seen.
6	To $1\text{ cm}$ depth of S in a test-tube, add about the same volume of dilute sulfuric acid. To the mixture in the test-tube, add a small amount of R and mix well.
7	To $1\text{ cm}$ depth of S in a test-tube, add about the same volume of aqueous hydrogen peroxide.
8	(a) To $1\text{ cm}$ depth of aqueous potassium iodide in a test-tube, add about the same volume of dilute sulfuric acid. To the mixture, add a few drops of S. (b) To the mixture from (a), add a few drops of starch solution. (c) To the mixture from (b), add a small amount of R and mix well.
9	To $1\text{ cm}$ depth of S in a test-tube, add about the same volume of aqueous sodium hydroxide. To the mixture add a small amount of R, mix well and leave to stand.

(conclusions) In tests 1 and 5, R is acting as ______ .

In test 8, S is acting as ______ .

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Q22016 Oct/Nov·P3123MMediumQualitative Analysis

You are provided with solution R and solid S.
Carry out the following tests and record your observations in the table.
You should test and name any gas evolved.

test no.	test	observations
1	(a) To $1\text{ cm}$ depth of R in a boiling tube, add 2 drops of litmus solution. (b) To the mixture from (a), add about twice the volume of aqueous sodium hydroxide. Keep this mixture for use in test 2.
2	To the mixture from test 1, add a piece of aluminium and warm the boiling tube until reaction just begins.
3	(a) To $1\text{ cm}$ depth of R in a boiling tube, add an equal volume of aqueous iron(II) sulfate. Heat the mixture until the liquid just begins to boil. (b) To the mixture from (a), add aqueous sodium hydroxide until no further change occurs.
4	To $2\text{ cm}$ depth of R in a test-tube, add a piece of magnesium.
5	To $2\text{ cm}$ depth of R in a test-tube, add a small amount of S. Keep this solution for use in tests 6 and 7.
6	Transfer about half of the solution from test 5 to a test-tube and add aqueous sodium hydroxide until no further change occurs.
7	To the rest of the solution from test 5 in a test-tube, add aqueous ammonia until no further change occurs.
8	To a small amount of S in a hard-glass test-tube, add an equal amount of ammonium chloride and mix the solids together. Heat the mixture.

(Conclusions) Give the formula of a cation and the formula of an anion in R.

The formula of a cation in R is ______ .
The formula of an anion in R is ______ .

Give the formula of a cation and the formula of an anion in S.

The formula of a cation in S is ______ .
The formula of an anion in S is ______ .

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Q12015 Oct/Nov·P317 partsMedium-HardExperimental Contexts

(a)

Put P into the burette.

Pipette a $25.0\text{ cm}^3$ (or $20.0\text{ cm}^3$ ) portion of Q into a flask and titrate with P, using the indicator provided.

Record your results in the table, repeating the titration as many times as you consider necessary to achieve consistent results.

Results

Burette readings

titration number	1	2
final reading / $\text{cm}^3$
initial reading / $\text{cm}^3$
volume of P used / $\text{cm}^3$
best titration results (✓)

Summary

Tick (✓) the best titration results.

Using these results, the average volume of P required was ______ $\text{cm}^3$ .

Volume of Q used was ______ $\text{cm}^3$ .

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(b)

Q is $0.336\text{ mol / dm}^3$ sodium hydroxide, $\text{NaOH}$ .

Calculate the number of moles of sodium hydroxide in the volume of Q used.

moles of sodium hydroxide in the volume of Q used = ______

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(c)

Using the equation shown and your answer to (b), deduce the number of moles of hydrochloric acid that reacted with the volume of Q used.

\text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O}

moles of hydrochloric acid that reacted with the volume of Q used = ______

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(d)

Using your answer to (c) and the average volume of P from the titration results, calculate the number of moles of hydrochloric acid in $250\text{ cm}^3$ of P.

moles of hydrochloric acid in $250\text{ cm}^3$ of P = ______

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(e)

Calculate the number of moles of hydrochloric acid in $250\text{ cm}^3$ of $0.500\text{ mol / dm}^3$ hydrochloric acid.

moles of hydrochloric acid in $250\text{ cm}^3$ of $0.500\text{ mol / dm}^3$ hydrochloric acid = ______

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(f)

Using your answers from (d) and (e), calculate the number of moles of hydrochloric acid that reacted with the calcium carbonate in the tablets.

moles of hydrochloric acid that reacted with calcium carbonate = ______

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(g)

Using your answer to (f), calculate the mass of calcium carbonate in one tablet of the antacid.

The relative formula mass of calcium carbonate is 100.

mass of calcium carbonate in one tablet of the antacid = ______ $\text{g}$

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