Qualitative Colour changes

Question 1

What colour is Cu²⁺(aq)?

Answer 1

Blue

Question 2

What colour is Fe²⁺(aq)?

Answer 2

Pale green

Question 3

What colour is Fe³⁺(aq)?

Answer 3

Yellow / brown

Question 4

What colour is Cr₂O₇²⁻(aq)?

Answer 4

Orange

Question 5

What colour is CrO₄²⁻(aq)?

Answer 5

Yellow

Question 6

What colour is MnO₄⁻(aq)?

Answer 6

Purple

Question 7

What colour is I₂ in aqueous solution?

Answer 7

Brown

Question 8

What colour is I₂ in organic solvent?

Answer 8

Purple

Question 9

What colour is Br₂(aq) / bromine water?

Answer 9

Orange

Question 10

What colour is Cl₂(aq)?

Answer 10

Pale green

Question 11

What colour is hydrated CuSO₄?

Answer 11

Blue

Question 12

What colour is anhydrous CuSO₄?

Answer 12

White

Question 13

What colour is Cu₂O?

Answer 13

Red

Question 14

What colour is CuO?

Answer 14

Black

Question 15

What is the colour change for acidified manganate(VII) in redox reactions?

Answer 15

Purple to colourless

Question 16

What is the colour change for acidified dichromate(VI) in redox reactions?

Answer 16

Orange to green

Question 17

What is the flame colour of Li⁺?

Answer 17

Crimson red

Question 18

What is the flame colour of Na⁺?

Answer 18

Yellow

Question 19

What is the flame colour of K⁺?

Answer 19

Lilac

Question 20

What is the flame colour of Ca²⁺?

Answer 20

Brick red

Question 21

What is the flame colour of Ba²⁺?

Answer 21

Apple green

Question 22

What is the flame colour of Cu²⁺?

Answer 22

Blue-green

Question 23

What is the observation when a chloroalkane reacts with silver nitrate?

Answer 23

White precipitate

Question 24

What is the observation when a bromoalkane reacts with silver nitrate?

Answer 24

Cream precipitate

Question 25

What is the observation when an iodoalkane reacts with silver nitrate?

Answer 25

Yellow precipitate

Question 26

What is the positive result of the iodoform test?

Answer 26

Yellow precipitate

Question 27

What is the positive result when 2,4-DNPH reacts with an aldehyde or ketone?

Answer 27

Deep orange precipitate

Question 28

What is the observation when an aldehyde reacts with Fehling’s solution?

Answer 28

Blue solution gives a red precipitate

Question 29

What is the observation when an aldehyde reacts with Tollens’ reagent?

Answer 29

Silver mirror forms

Question 30

What is the observation when sodium reacts with an alcohol?

Answer 30

White solid of sodium alkoxide forms

Question 31

What is the observation when iodine reacts with starch?

Answer 31

Blue-black colour forms

Question 32

What is the colour change of hydrated cobalt chloride paper in the presence of water?

Answer 32

Blue to pink