Qualitative Analysis

Question 1

What are all the elements that can be detected by qualitative analysis?

Answer 1

Hydrogen, H2
Oxygen, O2
Chlorine, Cl2
Iodine, I2

Question 2

What are all the compounds that can be detected by qualitative analysis?

Answer 2

Carbon dioxide, CO2
Hydrogen chloride, HCl
Ammonia, NH3

Question 3

What are all the cations that can be detected by qualitative analysis?

Answer 3

Lithium, Li+
Sodium, Na+
Potassium, K+
Calcium, Ca+
Barium, Ba2+
Copper(II), Cu2+
Ammonium, NH4+

Question 4

What are all the anions that can be detected by qualitative analysis?

Answer 4

Chloride, Cl-
Bromide, Br-
Iodide, I-
Sulfate, SO4 2-
Carbonate, CO3 2-

Question 5

What are the properties of hydrogen?

Answer 5

Colourless gas
Odourless gas
Less dense than air

Question 6

What is the chemical test for hydrogen?

Answer 6

Place burning splint in inverted test tube filled with the gas.

Question 7

What are the observations from the chemical test for hydrogen?

Answer 7

Gas burns with pop sound.

Question 8

What are the properties of oxygen?

Answer 8

Colourless gas
Odourless gas

Question 9

What is the chemical test for oxygen?

Answer 9

Place glowing splint in inverted test tube filled with the gas.

Question 10

What are the observations from the chemical test for oxygen?

Answer 10

Gas relights glowing splint.

Question 11

What are the properties of chlorine?

Answer 11

Green gas
Pungent odour of bleach
Less dense than air.

Question 12

What is the chemical test for chlorine?

Answer 12

Bring the gas into contact with damp blue litmus paper or damp Universal Indicator paper.

Question 13

What are the observations from the chemical test for chlorine?

Answer 13

Turns damp indicator paper red then bleaches paper.

Question 14

What are the properties of aqueous iodine?

Answer 14

Yellow solution (dilute)

Question 15

What is the chemical test for aqueous iodine?

Answer 15

Add several drops of starch solution.

Question 16

What are the observations from the chemical test for aqueous iodine?

Answer 16

Blue-black coloured solution formed.

Question 17

What are the properties of carbon dioxide?

Answer 17

Colourless gas
Odourless gas
Denser than air
Soluble in water

Question 18

What is the chemical test for carbon dioxide?

Answer 18

Bubble the gas through limewater.

Question 19

What are the observations from the chemical test for carbon dioxide?

Answer 19

Cloudy white suspension turns limewater milky.

Question 20

What are the properties of hydrogen chloride?

Answer 20

Colourless gas
Pungent odour
Denser than air
Soluble in water

Question 21

What is the chemical test for hydrogen chloride?

Answer 21

Bring gas into contact with glass rod dipped in concentrated ammonia.

Question 22

What are the observations from the chemical test for hydrogen chloride?

Answer 22

White fumes of solid ammonium chloride are formed.

Question 23

What are the properties of ammonia?

Answer 23

Colourless gas
Pungent gas
Less dense than air
Soluble in water

Question 24

What is the chemical test for ammonia?

Answer 24

Bring gas into contact with glass rod dipped in concentrated hydrochloric acid.

Question 25

What are the observations from the chemical test for ammonia?

Answer 25

White fumes of solid ammonium chloride are formed.

Question 26

What is the method for the flame tests?

Answer 26

1. Wash end of nichrome wire in concentrated hydrochloric acid. 2. Transfer small amount of solid onto wire by dipping end of wire in solid. 3. Place solid sample in blue Bunsen flame and record flame colour.

Question 27

What are the observations for the flame tests for cations?

Answer 27

Sodium - yellow / orange Lithium - crimson Calcium - brick red Barium - apple-green Copper - blue-green Potassium - lilac

Question 28

What is the method for testing for ammonium ions?

Answer 28

1 - Add spatula of solid to test tube containing 4-5cm^3 of dilute sodium hydroxide solution. 2 - Warm mixture gently and test any gas evolved using glass rod dipped in concentrated hydrochloric acid.

Question 29

What are the observations at each stage of testing for ammonium ions?

Answer 29

1 - Solid dissolves to give colourless solution. 2 - Pungent smell, white fumes of ammonium chloride formed.

Question 30

What is the method for testing for sulfate ions?

Answer 30

1 - Add spatula of solid to test tube containing 2-3cm^3 of water and shake to dissolve. 2 - Add 3-4 drops of barium chloride solution and shake to mix.

Question 31

What are the observations at each stage of testing for sulfate ions?

Answer 31

1 - Solid dissolves 2 - White precipitate formed

Question 32

What is the method for testing for carbonate ions?

Answer 32

1 - Add spatula of solid to test tube containing 2-3cm^3 of water. 2 - Add 1cm^3 of dilute nitric acid to solution and collect any gas evolved with pipette. 3 - Bubble contents of pipette through 2-3cm^3 of limewater in separate test tube.

Question 33

What are the observations at each stage of testing for carbonate ions?

Answer 33

1 - Solid dissolves 2 - Effervescence, colourless gas produced 3 - Cloudy white suspension turns limewater milky

Question 34

What is the method for testing for halide ions?

Answer 34

1 - Add spatula of solid to test tube containing 2-3cm^3 of water and shake to mix. 2 - Add 1cm^3 of dilute nitric acid followed by 3-4 drops of acidified silver nitrate solution. 3 - Add 4-5cm^3 of dilute ammonia solution and shake to mix. 4 - Repeat step 2 then add 4-5cm^3 of concentrated ammonia solution and shake to mix.

Question 35

What are the observations at each stage of testing for the halide ion chloride?

Answer 35

1 - Solid dissolves 2 - White precipitate formed. 3 - Precipitate dissolves.

Question 36

What are the observations at each stage of testing for the halide ion bromide?

Answer 36

1 - Solid dissolves 2 - Cream precipitate formed 3 - Precipitate does not dissolve 4 - Precipitate dissolves

Question 37

What are the observations at each stage of testing for the halide ion iodide?

Answer 37

1 - Solid dissolves 2 - Yellow precipitate formed 3 - Precipitate does not dissolve 4 - Precipitate does not dissolve

Question 38

What is the method for testing for cations using sodium hydroxide / ammonia?

Answer 38

1 - If solid salt, dissolve a spatula in water. 2 - Add few drops of sodium hydroxide / ammonia. 3 - Add more drops after ppt forms until in excess.

Question 39

What are the observations for copper (II) (Cu 2+) when testing for cations?

Answer 39

Few drops - blue ppt Excess - ppt remains

Question 40

What are the observations for iron (II) (Fe 2+) when testing for cations?

Answer 40

Few drops - green ppt Excess - ppt remains

Question 41

What are the observations for iron (III) (Fe 3+) when testing for cations?

Answer 41

Few drops - brown ppt Excess - ppt remains

Question 42

What are the observations for magnesium (Mg 2+) when testing for cations?

Answer 42

Few drops - white ppt Excess - ppt remains

Question 43

What are the observations for aluminium (Al 3+) reacting with sodium hydroxide when testing for cations?

Answer 43

Few drops - white ppt Excess - ppt dissolves into colourless solution

Question 44

What are the observations for aluminium (Al 3+) reacting with ammonia when testing for cations?

Answer 44

Few drops - white ppt Excess - ppt remains

Question 45

What are the observations for zinc (Zn 2+) when testing for cations?

Answer 45

Few drops - white ppt Excess - ppt dissolves into colourless solution