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IGCSEChemistry: Co-ordinated Sciences (Double Award)CIEExam QuestionsExperimental Techniques & Chemical AnalysisIdentification of Ions & Gases

Identification of Ions & Gases (CIE IGCSE Chemistry: Co-ordinated Sciences (Double Award))

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Identification of Ions & Gases

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Identification of Ions & Gases

1a1 mark

Two solids, L and M, were analysed. Solid L was copper(II) chloride and solid M was a different salt.
The tests on the solids, and some of the observations, are shown.

Tests on solid L

Describe the appearance of solid L.

How did you do?

1b7 marks

Distilled water was added to solid L (copper(II) chloride) and shaken to dissolve.
The solution was divided into four equal portions in four test-tubes and the following tests carried out.

 
i)
Drops of aqueous ammonia were added to the first portion of the solution.
Excess ammonia solution was then added to the mixture and shaken.
Observation:

[4]

ii)
Excess aqueous sodium hydroxide was added to the second portion of the solution.
Observation:

[1]

iii)
Dilute nitric acid was added to the third portion of the solution followed by aqueous silver nitrate.
Observation:
[1]
iv)
Dilute nitric acid was added to the fourth portion of the solution followed by aqueous barium nitrate.
Observation:
[1]

How did you do?

1c2 marks

Tests on solid M.
Tests are carried out and the following observations made.

cie-q2-table

Identify solid M.

How did you do?

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2a3 marks

A solid U was analysed. U was a soluble metal sulfate.
The tests on U, and some of the observations are in the following table.

Complete the observations.

 
Tests Observations
Test 1: Appearance of solid U. Pink crystals
Test 2: Solid U was heated gently and then strongly in a test-tube. condensation droplets formed on the sides of the test-tube

Solid U was added to distilled water in a test-tube and shaken until dissolved.

Test 3 part (i): The solution was divided into three equal portions in separate test-tubes and the following tests carried out.
Several drops of aqueous sodium hydroxide were added to the first portion of the solution and the test-tube shaken.

pale brown precipitate

Test 3 part(ii): Then hydrogen peroxide solution was added to the mixture and the gas given off was tested.

effervescence
glowing splint re-lit
Test 4: Dilute nitric acid was added to the second portion of the solution followed by barium nitrate solution.  
Test 5: Dilute nitric acid was added to the third portion of the solution followed by silver nitrate solution.  

i)
State the expected observations for Test 4.

[2]

ii)
State the expected observations for Test 5.

[1]

How did you do?

2b1 mark

What does Test 5 tell you about solid U?

How did you do?

2c1 mark

Name the gas given off in Test 3.

How did you do?

2d2 marks

What conclusions can you draw about solid U?

How did you do?

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3a1 mark

A student investigated the products formed when ethanol was burned using the apparatus shown.

combustion-demo-add-labels

Complete the box to identify the piece of apparatus.

How did you do?

3b1 mark

Why is a suction pump used?

How did you do?

3c3 marks
i)
Suggest the purpose and identity of liquid F.
 
identity .......................................................................................................................
 
purpose ................................................................................................................
 
[2]
 
ii)
Why is the end of the delivery tube below the surface of liquid F?
 
[1]

How did you do?

3d2 marks

Give one expected observation in the horizontal part of the delivery tube.

Explain your answer.

How did you do?

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4a3 marks

A solid D, which is a soluble metal sulfate, was analysed.
The tests on D, and some of the observations, are in the following table.

Complete the observations in the table.

 
Tests Observations

Test 1 on solid D

(i) Appearance of solid D.
(ii) Solid D was heated in a test-tube gently and then strongly.

(i) Pale green crystals

(ii) Condensation formed at the top of the test-tube

Test 2 on the aqueous solution


Solid D was added to distilled water and shaken to dissolve. The solution was divided into four equal portions in
separate test-tubes.
(i) Several drops of aqueous sodium hydroxide were added to the first portion of the solution.
(ii) Excess aqueous sodium hydroxide was added to the mixture.
(ii) Excess aqueous ammonia was added to the second portion of the solution.

(i) Green precipitate

(ii) Green precipitate remained

(iii) Green precipitate

Test 3

Aqueous silver nitrate and dilute nitric acid were added to the third portion of the solution.

 

Test 4

Aqueous barium nitrate and dilute nitric acid were added to the fourth portion of the solution.

  

i)
State the expected observation for Test 3.

[1]

ii)
State the expected observation for Test 4.

[2]

How did you do?

4b2 marks

What does Test 1 tell you about solid D?

How did you do?

4c3 marks

What conclusions can you draw about the identity of solid D?

How did you do?

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5a4 marks

Two liquids, L and M, were analysed. L was aqueous potassium iodide. M was a colourless liquid.
The tests on the liquids and some of the observations are in the following table.

Complete the observations in the table.

 
Tests Observations
Test 1 on liquid L
Appearance of liquid L		  

Test 2

Liquid L was divided into three equal portions in separate test-tubes.
(i) An iodine crystal was added to the first portion of liquid L. The test-tube was stoppered and the contents shaken.
(ii) An equal volume of liquid M was added to the test-tube, the contents shaken and left to stand for five minutes.

(i) liquid turned orange

(ii) two layers were formed, pink top layer and orange lower layer

Test 3

To the second portion of liquid L, dilute nitric acid and barium nitrate solution were added.

  

Test 4

To the third portion of liquid L, dilute nitric acid and silver nitrate solution were added.

  

i)
Describe the appearance of liquid L in Test 1.

[1]

ii)
Describe the observation made as a result of Test 3.

[1]

iii)
Describe the observation made as a result of Test 4.

[2]

How did you do?

5b1 mark

Why does the colour of liquid L change in Test 2 part (i)?

How did you do?

5c2 marks

What conclusions can you draw about liquid M from Test 2 part (ii)?

How did you do?

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6a7 marks

Solid C was analysed. Solid C was a mixture of salts containing aluminium ions, sulfate ions and another cation (positive ion).
Tests on solid C, and some of the observations, are in the table.

Complete the observations in the table.

gzTiMy5I_12-3-q5a

How did you do?

6b1 mark

What does the formation of condensation in test (b) tell you about the nature of solid C?

How did you do?

6c1 mark

What does test (iii) tell you about the nature of solid C?

How did you do?

6d2 marks
i)
Name the gas given off in test (b).
[1]
ii)
What is your conclusion about the identity of the other cation in solid C?
[1]

How did you do?

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7a1 mark

Two metal salt solutions, X and Y, were analysed. Solution X was iron(II) chloride.
The tests on X and Y, and some of the observations, are given in the following tables.
Complete the observations in the tables.

test observations

tests on solution X

Appearance of solution X


............................................................................ 

How did you do?

7b1 mark

The solution was divided into four equal portions.

tests observations

Dilute nitric acid and aqueous silver nitrate were added to the first portion of solution

 ............................................................................ 

How did you do?

7c2 marks

tests observations

Aqueous sodium hydroxide was added to the second portion of solution and the mixture shaken

 ............................................................................ 

How did you do?

7d1 mark

tests observations

Excess aqueous ammonia was added to the third portion of solution.

 ............................................................................ 

How did you do?

7e1 mark

tests observations

tests on solution Y


The solution was divided into three equal portions.

Dilute hydrochloric acid was added to the first portion of the solution.

white precipitate formed

Aqueous sodium hydroxide was added to the second portion of the solution and the mixture shaken.
Aluminium powder was added to the mixture and it was warmed gently. The gas given off was tested with damp red litmus paper.

effervescence


pungent gas evolved, litmus paper turned blue

Aqueous potassium iodide was added to the third portion of the solution.

pale yellow precipitate

What conclusions can you draw about solution Y?

How did you do?

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8a8 marks

A mixture of two solids, M and N, was analysed.
Solid M was zinc sulfate which is water-soluble and solid N was insoluble.
The tests on the mixture, and some of the observations, are in the table.

Complete the observations in the table.

 
Tests Observations
Distilled water was added to the mixture in a boiling tube and shaken. The contents of the tube were filtered and the filtrate and residue kept for the following tests.  

The filtrate was divided into four portions.

  

Test 1

(i) Drops of aqueous sodium hydroxide were added to the first portion of the filtrate.
Excess aqueous sodium hydroxide was then added.

 
(ii) Drops of aqueous ammonia were added to the second portion of the filtrate.
Excess aqueous ammonia was then added.

  

Test 2

About 1 cm3 of dilute nitric acid followed by silver nitrate solution was added to the third portion of the filtrate.

  

Test 3

About 1 cm3 of dilute nitric acid followed by barium nitrate solution was added to the fourth portion of the filtrate.

  

Test 4

Tests on the residue

Appearance of the residue.

 black solid

Test 5

Dilute hydrochloric acid was added to a little of the residue. The mixture was heated and the gas given off was tested
with damp blue litmus paper.

effervescence

pungent gas, bleached litmus paper

Test 6

Aqueous hydrogen peroxide was added to a little of the residue.

The gas given off was tested.

effervescence

 
glowing splint re-lit

i)
State the expected observation in Test 1 part (i).

[3]

ii)
State the expected observation in Test 1 part (ii).

[2]

iii)
State the expected observation in Test 2.

[1]

iv)
State the expected observation in Test 3.

[2]

How did you do?

8b1 mark

Identify the gas given off in Test 5.

How did you do?

8c1 mark

Identify the gas given off in Test 6.

How did you do?

8d2 marks

What conclusions can you draw about solid N?

How did you do?

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9a5 marks

Two different liquids, M and N, were analysed. N was aqueous potassium iodide.
The tests on the liquids and some of the observations are in the following table.

Complete the observations in the table.

 
Tests Observations

Test 1

Appearance of liquid M.

 Colourless liquid with an antiseptic smell

Test 2

Appearance of liquid N.

  

Test 3

A few drops of M were transferred to a dry watch glass.

The liquid was touched with a lighted splint.

 Burns with a yellow flame

Test 4

Test 3 was repeated using liquid N.

  

Test 5

A little of liquid M was added to a crystal of iodine in a test-tube.

The test-tube was shaken.

 Orange-brown solution

Test 6

To a little of liquid N, a few drops of dilute nitric acid was added, followed by silver nitrate solution.

  

i)
State the appearance of liquid N in Test 2.

[2]

ii)
State the observation from using liquid N in Test 4.

[1]

iii)
State the observation in Test 6.

[2]

How did you do?

9b2 marks

What type of substance is liquid M?

How did you do?

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10a6 marks

Three different liquids P, Q and R were analysed.
P was an aqueous solution of sulfuric acid.
The tests on the liquids and some of the observations are in the following table.

Complete the observations in the table.

 
Tests Observations
i) The appearance of the liquids.  P ............................................................... [1]
 Q colourless, smell of vinegar
 R colourless, no smell
ii) The pH of the liquids was tested using Universal Indicator paper.  P ............................................................... [1]
 Q pH 5
 R pH 7
iii) A piece of magnesium ribbon was added to a little of each liquid.
The gas given off by liquid P was tested.		  P .....................................................................
  ................................................................. [2]
 Q slow effervescence
 R no reaction
iv) To a little of liquid P, hydrochloric acid and aqueous barium chloride was added.   ............................................................... [2]

Liquid R was heated to boiling in a test-tube.

A thermometer was used to record the constant temperature of the vapour produced.

  Temperature = 100 °C

How did you do?

10b1 mark

Identify liquid R.

How did you do?

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116 marks

Three bottles of liquids have lost their labels.
The liquids are known to be:

Aqueous sodium iodide,
Hexene,
Dilute nitric acid.

Outline chemical tests you could use to distinguish between the liquids in the three bottles.

 

liquid test result
aqueous sodium iodide    
hexene    
dilute nitric acid    

How did you do?

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12a6 marks

Two different solutions, X and Y, were analysed. X was copper sulfate solution.
The tests on the solutions, and some of the observations, are in the following table.

Complete the observations in the table.

 
Tests Observations

Test 1

Appearance of solution X.

i) ................................................................

[1]

Test 2

To a little of solution X, aqueous sodium hydroxide was added.

ii) ................................................................

[2]

Test 3

To a little of solution X, aqueous ammonia was added drop by drop and shaken.

iii) ................................................................

[1]

Test 4

Excess aqueous ammonia solution was then added to the test-tube of solution X in aqueous ammonia.

iv) ................................................................

[2]

Test 5

A little of solution Y was tested with Universal Indicator paper. The pH was recorded.

  pH 1

Test 6

To about 3 cm3 of solution Y a few drops of dilute hydrochloric acid and then aqueous barium chloride was added.

  White precipitate

How did you do?

12b2 marks

Identify solution Y.

How did you do?

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13a2 marks

Describe a chemical test to distinguish between each of the following pairs of substances.
An example is given.


Example: hydrogen and carbon dioxide
Test: lighted splint
Result with hydrogen: gives a pop
Result with carbon dioxide: splint is extinguished

 

Describe a test to distinguish between zinc carbonate and zinc chloride


Test: ..................................................................................................................

Result with zinc carbonate: .....................................................................
Result with zinc chloride: ..........................................................................

How did you do?

13b3 marks

Describe a test to distinguish between ammonia and chlorine:
Test: .........................................................................................................................................
Result with ammonia: ......................................................................................................
Result with chlorine: .........................................................................................................

How did you do?

13c3 marks

Describe a test to distinguish between aqueous iron(II) sulfate and aqueous iron(III) sulfate.

 
Test: ..........................................................................................................................................
Result with aqueous iron(II) sulfate: ............................................................................
Result with aqueous iron(III) sulfate: ...........................................................................

How did you do?

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14a7 marks

Two solids, S and V, were analysed. S was copper(II) oxide.
The tests on the solids, and some of the observations are in the following table.

Complete the observations in the table. Do not write any conclusions in the table.

 
Tests Observations
Appearance of solid S  Black solid
Hydrogen peroxide was added to solid S in a test tube, and a glowing splint then inserted into the tube.  Slow effervescence, splint relit

Dilute sulfuric acid was added to solid S in a test-tube. The mixture was heated to boiling point.

  Blue solution formed

The solution was divided into three equal portions into test-tubes.

To the first portion of the solution, excess sodium hydroxide was added.

i) .....................................................

[1]

To the second portion of the solution, about 1 cm3 of aqueous ammonia solution was added.

ii) .....................................................

[2]
Excess ammonia solution was then added to the second portion.

iii) .....................................................

[2]
To the third portion of the solution, dilute hydrochloric acid was added followed by barium chloride solution.

iv) .....................................................

[2]

How did you do?

14b2 marks

The results from tests on the solid V are shown below.

 
Tests Observations

Test 1

Appearance of solid

  Black solid

Test 2

Hydrogen peroxide was added to solid V in a test-tube.
A glowing splint was inserted into the tube.

  Rapid effervescence, splint relit

i)
Compare the reactivity of solid S and solid V with hydrogen peroxide.

[1]

ii)
Identify the gas given off in Test 2.

[1]

How did you do?

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15a2 marks

The apparatus below was used to make oxygen. The tube of manganese oxide was added to the hydrogen peroxide solution by releasing the cotton.

cie-collection-of-gas

 

Complete the boxes to identify the pieces of apparatus.

How did you do?

15b1 mark

Why was the tube of manganese oxide suspended in the flask?

How did you do?

15c2 marks

Give a test for oxygen.
Test: .................................................................................
Result: .............................................................................

How did you do?

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16a2 marks

Three unlabelled bottles of chemicals each contained one of the following liquids:
• sodium nitrate dissolved in water
• pure water
• hexene

Give a test by which you could identify sodium nitrate solution.
Test: .......................................................................................................................................
Result: ...................................................................................................................................

How did you do?

16b2 marks

Give a test by which you could identify pure water.
Test: ......................................................................................................
Result: ..................................................................................................

How did you do?

16c2 marks

Give a test by which you could identify hexene.
Test: .............................................................................................
Result: .........................................................................................

How did you do?

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17a5 marks

An aqueous solution of substance X was analysed. Substance X was an iron(III) salt containing one other cation. The tests on X and some of the observations are in the following table. Complete the observations in the table

tests observations
Colour of solution X
 dark yellow
i)
Drops of aqueous sodium hydroxide were added to about 2 cm3 of the solution. Excess aqueous sodium hydroxide was added to the test-tube.

The mixture was heated. The gas given off was tested with damp indicator paper.

..........................................................................................

..........................................................................................

[3]

pungent smell, indicator turned blue,pH 10
ii)
Experiment (i) was repeated using aqueous ammonia instead of aqueous sodium hydroxide

..........................................................................................

..........................................................................................

[2]

To about 2 cm3 of solution X was added dilute sulphuric acid. Two pieces of zinc were added. The mixture was heated and the gas given off tested.

After 10 minutes the mixture was filtered and test (a)(i) was repeated

lighted splint popped 




green precipitate insoluble in excess
A few drops of hydrochloric acid were added to about 2 cm3 of solution X. About 1 cm3 of barium chloride solution was added to the mixture.  white precipitate

How did you do?

17b3 marks
i)
Name the gas given off when sulfuric acid was added to the solution.
[1]
ii)
What type of chemical reaction occurs in (d). Explain your answer.
[2]

How did you do?

17c2 marks

What conclusions can you draw about the anion and the other cation in substance X?

anion ................................................................................................................................
cation ................................................................................................................................

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18a2 marks

Describe a chemical test to distinguish between each of the following pairs of substances.

An example is given.

   oxygen and carbon dioxide
   test: glowing splint
   result: re-lights in oxygen, no effect with carbon dioxide 

aqueous chlorine and aqueous sodium chloride

test ..................................................................................................
result with chlorine .........................................................................................................
result with sodium chloride ..........................................................................................................

How did you do?

18b2 marks

aqueous iron(II) chloride and aqueous iron(III) chloride

test ..................................................................................................
result with iron(II) chloride .............................................................................................................
result with iron(III) chloride ...........................................................................................................

How did you do?

18c2 marks

copper sulphate and copper carbonate

test .............................................................
result with copper sulphate ........................................................................
result with copper carbonate .....................................................................

How did you do?

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19a8 marks

Salt E, which is ammonium chloride was tested.

Record all observations in the table.  

tests observations
 i)
Describe the appearance of E

 ................................................................................

[2]
 
 Using a spatula salt E was placed in a hard glass test-tube.
 Inside the top of the tube was suspended a piece of damp   blue litmus paper next to a piece of damp red litmus paper.   E was heated gently until gas came out of the tube.

     Red litmus went blue then blue litmus went red

 E was dissolved in water to make an aqueous solution. The   solution was divided into three test-tubes:

ii)
To the first portion, was added a few drops of dilute
nitric acid and about 1 cm3 of aqueous silver nitrate.
iii)
To the second portion of solution E, was added about 1 cm3 of lead nitrate solution.
iv)
To the third portion of solution E, was added about
1 cm3 of aqueous sodium hydroxide. The mixture was
boiled gently and the gas given off was tested with
indicator paper

 ................................................................................

[2]


 ................................................................................

[2]


 ................................................................................

[2] 

How did you do?

19b1 mark

Name the gas given off in test a) iv).

How did you do?

19c2 marks

Explain the litmus observations.

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20a6 marks

A mixture of two solid compounds D and E was analysed. Solid D was a zinc salt which is soluble in water. Solid E was an insoluble metal carbonate. The tests on the mixture and some of the observations are in the following table.

Test 1: About half of the mixture of D and E was placed in a test-tube. The mixture was heated.

Observations:  Green to black, condensation formed

The rest of the mixture of D and E was added to distilled water in a boiling tube. The contents of the tube were filtered. The filtrate and the residue were kept for the following tests.

Complete observations for the following tests that were carried out on the residue

i)
Test 1:
The residue was transferred from the filter paper in to a test-tube. About 3 cm3 of dilute sulphuric acid was
added. The gas was tested with limewater. 

Observations: ....................................................................................................................

[2]
ii)
Test 2:
The solution obtained in (c) was divided into two equal portions.

The first portion was added excess aqueous sodium hydroxide, a little at a time.

Observations: pale blue precipitate

To the second portion was added excess aqueous ammonia, a little at a time.

Observations:  ....................................................................................................................
[4]

How did you do?

20b6 marks

Three tests were carried out on the filtrate. 

Complete the observations for each test.

The filtrate from (a) was divided into three approximately equal portions.

i)
Test 1: To the first portion were added drops of aqueous sodium hydroxide, a little at a time with shaking.

Observations: ...........................................................................................................................

[2]
Excess aqueous sodium hydroxide was added.

Observations:...........................................................................................................................
[1]

ii)
Test 2: To the second portion was added excess aqueous ammonia a little at a time.

Observations: ...........................................................................................................................
[3]
Test 3 : To the third portion were added drops of dilute hydrochloric acid and aqueous barium chloride.

Observations: white precipitate 

How did you do?

20c2 marks

What conclusions can you draw about the identity of solid D?

How did you do?

20d1 mark

What conclusion can you draw about the identity of the cation in solid E?

How did you do?

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21a2 marks

Describe a chemical test to distinguish between each of the following pairs of substances.
An example is given

potassium chloride and potassium iodide

test: add aqueous lead(II) nitrate
result: potassium chloride gives a white precipitate, potassium iodide gives a yellow precipitate

water and ethanol

test ...........................................................................................................................
result with water ...........................................................................................................................
result with ethanol  ...........................................................................................................................

How did you do?

21b2 marks

sulphuric acid and aqueous sodium sulphate

test ....................................................................................................................
result with sulphuric acid ....................................................................................................................
result with aqueous sodium sulphate  ....................................................................................................................

How did you do?

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22a2 marks

The apparatus below was used to make hydrogen. Dilute hydrochloric acid was added to zinc.

apparatus

Identify the pieces of apparatus labelled
A ................................................................................
B. ................................................................................

How did you do?

22b1 mark

Complete the boxes. 

How did you do?

22c2 marks

Give a test for hydrogen.

 
Test ...........................................................................................
Result ...........................................................................................

How did you do?

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23a4 marks

A sample of a solution of acid A was analysed.

The tests on A, and some of the observations are in the following table.

Complete the observations in the table.

 
tests observations
1) The pH of the solution was tested using indicator paper orange,     pH 4
The solution was divided into three test-tubes
2) To the first portion was added a piece of magnesium ribbon. The gas was tested with a lighted splint.

i) ..................................................     

[2]
3) To the second portion of A was added sodium carbonate. The gas was tested with limewater.

ii) ..................................................     

[2]
4) To the third portion of liquid A was added a spatula measure of solid B. The mixture was boiled gently.

By using a teat pipette the solution was transferred to another test tube. Excess aqueous ammonia was added.
green solution formed



dark blue solution formed

How did you do?

23b1 mark

What does test 1 tell you about the type of acid in solution A?

How did you do?

23c2 marks
i)
Name the gas given off in test 2.
 
[1]
 
ii)
Name the gas given off in test 3.
 
[1]

How did you do?

23d2 marks

Explain the observations in test 4.

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24a6 marks

A solid compound X was analysed. Solid X was an aluminium salt. The tests on X and some of the observations are written below. 

Test 1

One spatula measure of X was placed into a hard-glass test tube. The solid was heated gently then heated strongly. The gas was tested with pH indicator paper.

Observations:

Condensation at top of tube, paper went red

Complete the other observations.

 
Test 2

Distilled water was added to X and shaken to dissolve. The solution was divided into five portions in test-tubes. 

i)
To the first portion, drops of aqueous sodium hydroxide were added.
Excess aqueous sodium hydroxide was then added.
Observations: ......................................................................................................................................
[3]
ii)
To the second portion, drops of aqueous ammonia were added.
Excess ammonia was then added. 
Observations ......................................................................................................................................
[3]
To the third portion of solution, hydrochloric acid and barium chloride solution were added.
Observations: No visible change

To the fourth portion of solution, nitric acid and lead nitrate solution were added.
Observations: No visible change

To the fifth portion, aqueous sodium hydroxide and a spatula measure of aluminium granules were added. The mixture was warmed and the gas tested with indicator paper.
Observations: Pungent gas, paper went blue, pH 10

How did you do?

24b1 mark

What does Test 1 tell you about the gas given off?

How did you do?

24c2 marks

What conclusions can you draw about X from the tests done to the third and fourth portion of solution in part a).

Third portion: .......................................................................

Fourth portion: ....................................................................

How did you do?

24d1 mark

Identify the gas given off in the fifth portion in part a)

How did you do?

24e2 marks

What conclusions can you draw about substance X?

How did you do?

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25a4 marks

A mixture of two calcium compounds C and D was tested.
C is partially soluble in water and D is soluble in water

The mixture of C and D was added to distilled water in a boiling tube. The tube was shaken. The mixture was filtered.

The filtrate was divided into five equal portions.

Complete the observations for the identified tests.

i)
To the first portion was added drops of aqueous sodium hydroxide, a little at a time, with shaking.
Excess aqueous sodium hydroxide was added. 
Observations: ....................................................................................................................
[3]
ii)
To the second portion was added excess aqueous ammonia, a little at a time.
Observations: ....................................................................................................................
[1]
To the third portion was added dilute sodium hydroxide and aluminium powder. The mixture was boiled and the gas tested with damp litmus paper.
Observations: red litmus went blue 

The pH of the fourth portion was tested with indicator paper.
Observations: pH about 10 

Carbon dioxide was bubbled through the fifth portion
Observations: solution turned milky / cloudy 

How did you do?

25b1 mark

Name the gas given off in the test on the third portion.

How did you do?

25c1 mark

Suggest an explanation for the observation during the test to the fifth portion. 

How did you do?

25d2 marks

What conclusions can you draw about the identity of the anions in solids C and D?

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26a3 marks

A sample of solid C was analysed. C is a mixture of two salts, D and E. Solid D is insoluble lead carbonate and solid E is water-soluble.

The tests on C, and some of the observations are in the following table.

Complete the observations in the table.

 
tests observations
1. Describe the appearance of C. pale green solid
2. Using a spatula, place a little of C in a hard glass test-tube. Inside the top of the tube suspend a piece of damp indicator paper.
Heat C gently until gas comes out of the tube.		 paper turns blue
pH 8 to 11
3. Using a spatula, place a little of C in a test-tube. Add about 2cm3 of dilute nitric acid and test the gas.

..................................................
..................................................     
 
Solid C was added to a boiling tube containing distilled water. The tube was shaken to mix the contents. The contents of the boiling tube were filtered.
 
tests on the residue in the filter paper observations
4. Place the funnel in a test-tube.
Pour dilute nitric acid onto the residue contained in the funnel.
Add 2cm3 of potassium iodide to the solution collected in the tube.

yellow precipitate
 
tests on the filtrate observations
Divide the filtrate into three test-tubes
5. To the first portion add dilute hydrochloric acid and about 1cm3 of aqueous barium nitrate. white precipitate
6. To the second portion of solution, add excess aqueous ammonia. green precipitate 
7. To the third portion of solution, add an equal volume of aqueous sodium hydroxide.
 
Warm the mixture gently. Test the gas with indicator paper.

 
green precipitate

paper turned blue     

pH 8 - 11

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26b1 mark

Name the gas given off in test 3.

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26c1 mark

Name the gas given off in test 7.

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26d4 marks

What conclusions can you draw about salt E?

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27a7 marks

Three different liquids P, Q and R were analysed. Q was an aqueous solution of sodium hydroxide.

The tests on the liquids and some of the observations are shown in the following table.

Complete the observations in the table.

 
tests observations
1. Test the pH of the liquids using indicator paper. Note the colour of the paper.

   P = red     pH 1

i) Q = ..........     pH ..........     [2]

   R = orange     pH 5
2. Add a 5 cm piece of magnesium to about 3cm3 of liquid P in a test–tube.
Test the gas given off.

bubbles of gas given off
lighted splint pops
3. Repeat test 2 using liquids Q and R.
Do not test for any gases.

ii) Q .................................................

    R ..................................................     

[2]
4. To about 2cm3 of liquid, P add 1 spatula measure of sodium carbonate.

Test the gas given off.

iii) ............................................

..................................................

..................................................     

[3]
5. By using a teat pipette add aqueous silver nitrate to about 1 cm3 of liquid P.

white precipitate
6. By using a teat pipette add liquid Q to about 1 cm3 of aqueous iron(II) sulfate.

green precipitate

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27b1 mark

Name the gas given off in test 2.

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27c1 mark

Name the gas given off in test 4.

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27d1 mark

Identify liquid P.

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28a1 mark

Two salt solutions K and L were analysed. Each contained the same chloride anion but different metal cations. K was a copper(II) salt.

The tests on the solutions and some of the observations are in the following table.

Complete the observations in the table.

 
tests observations
1. Appearance of the solutions

K = ..................................................     

L = yellow
2. The pH of each solution was tested

K = pH 3

L = pH 2

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28b7 marks

The tests on solution K and some of the observations are in the following table.

Complete the observations in the table.

 
tests observations
3. Drops of aqueous sodium hydroxide were added to solution K. Excess aqueous sodium hydroxide was then added to the test-tube.

i) .............................................

.................................................

[2]

4. Experiment 3 was repeated using aqueous ammonia instead of aqueous sodium hydroxide.

ii) drops

........................................     [1]

iii) excess

........................................     [2]
5. A few drops of hydrochloric acid and about 1cm3 of barium
chloride solution were added to a little of solution K.

iv) ..................................................     

[1]
6. A few drops of nitric acid and about 1cm3 of silver nitrate solution were added to a little of solution K.

v) ..................................................     

[1]

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28c2 marks

The tests on solution L, and some of the observations, are in the following table.

Complete the observations in the table.

 
tests observations
7. Drops of aqueous sodium hydroxide were added to solution L. Excess aqueous sodium hydroxide was then added to the test-tube.

red-brown precipitate
8. Experiment 7 was repeated using aqueous ammonia instead of
aqueous sodium hydroxide.

red-brown precipitate
9. A few drops of hydrochloric acid and about 1cm3 of barium
chloride solution were added to a little of solution L.

i) ..................................................     

[1]
10. A few drops of nitric acid and about 1cm3 of silver nitrate solution were added to a little of solution L.

ii) ..................................................     

[1]

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28d1 mark

What does test 2 indicate?

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28e2 marks

Identify the metal cation present in solution L.

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