C.8 Identification of Ions and Gases

Question 1

Color seen in flame of lithium

Answer 1

crimson red

Question 2

Color seen in flame of sodium

Answer 2

orange

Question 3

Color seen in flame of potassium

Answer 3

lilac

Question 4

Color seen in flame of calcium

Answer 4

orange - red

Question 5

Color seen in flame of copper

Answer 5

Green

Question 6

Formula of lithium ion

Answer 6

Li+

Question 7

Formula of sodium ion

Answer 7

Na+

Question 8

Formula of potassium ion

Answer 8

K+

Question 9

Formula of copper ion

Answer 9

Cu+

Question 10

Formula of calcium ion

Answer 10

Ca+

Question 11

Result of calcium (Ca2+) ion in sodium hydroxide solution

Answer 11

• White precipitate of Ca(OH)2 formed

Question 12

Result of copper (II) (Cu2+) ion in sodium hydroxide solution

Answer 12

• Light blue precipitate formed

Question 13

Result of Iron (II) (Fe2+) ion in sodium hydroxide solution

Answer 13

• Green precipitate formed

- Starts to change to reddish brown in color after a few minutes

Question 14

Result of Iron (III) (Fe3+) ion in sodium hydroxide solution

Answer 14

Reddish-brown precipitate formed

Question 15

Result of zinc in sodium hydroxide solution

Answer 15

• White precipitate formed

- Dissolves in excess sodium hydroxide solution

Question 16

Formula of sodium hydroxide solution

Answer 16

OH-

Question 17

Ca2+ + 2OH- –> ?

Answer 17

Ca(OH)2

Question 18

Cu2+ + 2OH- –> ?

Answer 18

Cu(OH)2

Question 19

Fe3+ + 2OH- –> ?

Answer 19

Fe(OH)3

Question 20

Test for halide ions

Answer 20

• Add a small amount of nitric acid – to remove impurities

- Add Silver (I) Nitrate Solution

Question 21

All halide ions are soluble except for…

Answer 21

Silver halides

Question 22

Describe the test for chloride ions

Answer 22

To a solution of the chloride ions add:

1. Dilute nitric acid
2. Silver nitrate solution

Question 23

Describe the test for bromide ions

Answer 23

To a solution of the chloride ions add:

1. Dilute nitric acid
2. Silver nitrate solution

Question 24

Describe the test for Iodide ions

Answer 24

To a solution of the chloride ions add:

1. Dilute nitric acid
2. Silver nitrate solution

Question 25

Describe the test for sulfate ions

Answer 25

To a solution of sulfate ions add: 1. Dilute hydrochloric acid 2. Barium chloride solution

Question 26

Describe the test for nitrate ions

Answer 26

1. Add sodium hydroxide solution and warm 2. Add aluminum powder 3. Test any gas produced with damp red litmus paper

Question 27

Result of test for chloride ions

Answer 27

White precipitate (of AgCl)

Question 28

Result of test for bromide ions

Answer 28

Cream precipitate (of AgBr)

Question 29

Result of test for iodide ions

Answer 29

Yellow precipitate (of AgI)

Question 30

Result of test for sulfate ions

Answer 30

White precipitate (of BaSO4)

Question 31

Result of test for nitrate ions

Answer 31

Red litmus paper goes blue (ammonia gas produced)

Question 32

Test for carbonates (CO32-)

Answer 32

1. Add dilute HCl (hydrochloric acid) | 2. Bubble gas through limewater

Question 33

Result of test for carbonates (CO32-)

Answer 33

- effervescence (as CO2 is produced) | - Limewater turns cloudy

Question 34

Most metal sulphates are soluble, except for ___

Answer 34

Barium Sulphate

Question 35

Test for sulphates

Answer 35

Add small amount of HCl (hydrochloric acid) Add Barium Chloride solution

Question 36

Results of test for sulphates

Answer 36

- white precipitate of BaSO4 formed

Question 37

Test for nitrate ions

Answer 37

1. Add sodium hydroxide and warm it. 2. Reduce it with aluminum powder to produce ammonium ions. 3. The ammonium ions then react with the hydroxide to produce ammonia gas. 4. Test the ammonia gas with damp red litmus paper. As ammonia is basic it turns blue.

Question 38

Test for hydrogen gas (H2)

Answer 38

Hydrogen ignites with oxygen and creates a 'squeaky pop' sound

Question 39

Test for oxygen gas (O2)

Answer 39

Put in a glowing splint

Question 40

Method of squeaky pop test

Answer 40

Lit splint placed in mouth of test tube, a pop is heard.

Question 41

Result for test of oxygen gas (O2)

Answer 41

Splint relights if the test tube contains oxygen | gas.

Question 42

Test for carbon dioxide

Answer 42

Limewater test

Question 43

Method of limewater test

Answer 43

Pass carbon dioxide gas through limewater (calcium | hydroxide, Ca(OH)2)

Question 44

Result of test for carbon dioxide (CO2)

Answer 44

Limewater goes cloudy

Question 45

Test for chlorine gas (Cl2)

Answer 45

Litmus paper test

Question 46

Result of test for chlorine gas (C2)

Answer 46

Blue litmus paper goes red then white (bleached)

Question 47

Test for ammonia (NH3)

Answer 47

Dip in red litmus paper

Question 48

Result of test for ammonia (NH3)

Answer 48

Red litmus paper turns blue and strong smell is produced

Question 49

What is the cloudiness of limewater caused by?

Answer 49

Insoluble calcium carbonate

Question 50

Test for ammonium (NH4+)

Answer 50

Sodium hydroxide

Question 51

Test for copper (II) (Cu2+)

Answer 51

Sodium hydroxide

Question 52

Test for iron (II) (Fe2+)

Answer 52

Sodium hydroxide

Question 53

Test for iron (III) (Fe3+)

Answer 53

Sodium hydroxide

Question 54

Test for zinc (Zn2+)

Answer 54

Sodium hydroxide

Question 55

Test for Ammonia gas (NH3)

Answer 55

Red litmus paper test

Question 56

Result of test for Ammonia gas (NH3)

Answer 56

Turns damp red litmus paper blue.

Question 57

Why acid is added to test for sulfate ions and halide ions?

Answer 57

To remove impurities