Quantitative Analysis

Question 1

what are the different cations to be tested?

Answer 1

• ammonium
• zinc
• calcium
• lead (II)
• copper (II)
• iron (II)
• iron (III)

Question 2

what happens when ammonium reacts with aqueous sodium hydroxide?

Answer 2

no precipitate, colourless and pungent gas is given off (ammonia)

Question 3

what happens when ammonium reacts with aqueous ammonia

Answer 3

-

Question 4

what happens when zinc reacts with aqueous sodium hydroxide?

Answer 4

white precipitate soluble in excess sodium hydroxide forming a colourless solution

Question 5

what happens when zinc reacts with aqueous ammonia?

Answer 5

white precipitate soluble in excess aqueous ammonia forming a colourless solution

Question 6

what happens when calcium reacts with aqueous sodium hydroxide?

Answer 6

white precipitate insoluble in excess sodium hydroxide

Question 7

what happens when calcium reacts with aqueous ammonia?

Answer 7

no visible reaction

Question 8

what happens when lead (II) reacts with aqueous sodium hydroxide?

Answer 8

white precipitate soluble in excess sodium hydroxide forming a colourless solution

Question 9

what happens when lead (II) reacts with aqueous ammonia?

Answer 9

white precipitate insoluble in excess aqueous ammonia

Question 10

what happens when copper (II) reacts with aqueous sodium hydroxide?

Answer 10

blue precipitate insoluble in excess sodium hydroxide

Question 11

what happens when copper (II) reacts with aqueous ammonia?

Answer 11

blue precipitate soluble in excess aqueous ammonia forming a deep blue solution

Question 12

what happens when iron (II) reacts with aqueous sodium hydroxide?

Answer 12

dirty green precipitate insoluble in excess sodium hydroxide

Question 13

what happens when iron (II) reacts with aqueous sodium ammonia?

Answer 13

dirty green precipitate insoluble in excess aqueous ammonia

Question 14

what happens when iron (III) reacts with aqueous sodium hydroxide?

Answer 14

reddish brown precipitate insoluble in excess sodium hydroxide

Question 15

what happens when iron (III) reacts with aqueous ammonia?

Answer 15

reddish brown precipitate insoluble in excess aqueous ammonia

Question 16

what are the different anions to be tested?

Answer 16

• sulfate
• chloride
• nitrate
• carbonate

Question 17

how to test for sulfate?

Answer 17

add dilute nitric acid followed by aqueous barium nitrate into test tube

Question 18

what is observed in sulfate test?

Answer 18

no visible reaction on adding dilute nitric acid. white precipitate formed on adding barium nitrate

Question 19

how to test for chloride?

Answer 19

add dilute nitric acid followed by aqueous silver nitrate into test tube

Question 20

what is observed in chloride test?

Answer 20

no visible reaction on adding dilute nitric acid. white precipitate formed on adding silver nitrate

Question 21

how to test for nitrate?

Answer 21

add aqueous sodium hydroxide and add aluminium foil into the test tube. warm gently and test gas with moist red litmus paper

Question 22

what is observed in nitrate test?

Answer 22

effervescence observed. colourless and pungent gas is given off which turns moist red litmus paper blue (ammonia)

Question 23

how to test for carbonate?

Answer 23

add dilute hydrochloric acid and bubble the gas evolved into aqueous calcium hydroxide (limewater)

Question 24

what is observed in carbonate test?

Answer 24

effervescence observed. colourless and odourless gas is given off which forms a white precipitate in calcium hydroxide (carbon dioxide)

Question 25

what are the different gases to be tested?

Answer 25

- ammonia - carbon dioxide - chlorine - hydrogen - oxygen - sulfur dioxide

Question 26

how to test for ammonia?

Answer 26

place damp red litmus paper above the mouth of the test tube

Question 27

what is observed in ammonia test?

Answer 27

colourless and pungent gas produced which turns moist red litmus paper blue

Question 28

how to test for carbon dioxide?

Answer 28

bubble gas through aqueous calcium hydroxide (limewater)

Question 29

what is observed in carbon dioxide test?

Answer 29

white precipitate is formed

Question 30

how to test for chlorine?

Answer 30

place damp blue litmus paper at the mouth of the test tube

Question 31

what is observed in chlorine test?

Answer 31

damp blue litmus paper turns red and is then bleached

Question 32

how to test for hydrogen?

Answer 32

insert a lighted splint into the test tube

Question 33

what is observed in hydrogen test?

Answer 33

lighted splint extinguishes with a ‘pop’ sound

Question 34

how to test for oxygen?

Answer 34

insert a glowing splint into the test tube

Question 35

what is observed in oxygen test?

Answer 35

glowing splint will relight/burst into flames

Question 36

what is one way to test for sulfur dioxide?

Answer 36

place a filter paper strip soaked with acidified potassium manganate (VII) above the mouth of the test tube

Question 37

what is the observation of the first sulfur dioxide test?

Answer 37

the purple acidified potassium manganate (VII) decolourises

Question 38

what is a another test for sulfur dioxide?

Answer 38

place a filter paper soaked with acidified potassium dichromate (VI) above the mouth of the test tube

Question 39

what is observed in the second sulfur dioxide test?

Answer 39

the acidified potassium dichromate (VI) turns from orange to green