Identification of Ions & Gases (Cambridge (CIE) O Level Chemistry): Exam Questions

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.

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. (iii) 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.

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.

tests on solid C

(a) Appearance of solid C.

white solid

(b) A little of solid C was heated gently and then strongly. The gas given off was tested with damp pH indicator paper.

condensation was formed at the top of the test-tube

pungent gas, pH = 10

tests on a solution of C Water was added to solid C to produce an aqueous solution, solution C.

i) Drops of aqueous sodium hydroxide were added to solution C using a teat pipette. Excess aqueous sodium hydroxide was then added to the mixture. The mixture was boiled gently and any gases given off were tested.

.................................................. [3]

pungent gas, pH = 10

ii) Excess aqueous ammonia was added to solution C.

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

iii) A few drops of dilute nitric acid and aqueous silver nitrate were added to solution C.

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

iv) A few drops of dilute nitric acid and barium nitrate solution were added to solution C.

.................................................. [2]

test

observations

tests on solution X

Appearance of solution X

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

tests

observations

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

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

tests

observations

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

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

tests

observations

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

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

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

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

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.

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

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

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]

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

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 sulfuric 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

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] 

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

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 2 cm³ of dilute nitric acid and test the gas.

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

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

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 2 cm³ 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 1 cm³ 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

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 3 cm³ 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 2 cm³ 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

tests

observations

1. Appearance of the solutions

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

L = yellow

2. The pH of each solution was tested

K = pH 3

L = pH 2

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 1 cm³ of barium chloride solution were added to a little of solution K.

iv) .................................................. [1]

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

v) .................................................. [1]

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 1 cm³ of barium chloride solution were added to a little of solution L.

i) .................................................. [1]

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

ii) .................................................. [1]