Colours: Complexes, Flames, Gases, Solutions and Tests

Question 1

Tollens’ positive result

Answer 1

“Silver mirror” - aldehyde present

Question 2

Fehling’s positive result

Answer 2

“Blue clear –> red opaque” - aldehyde present

Question 3

Iron (III) chloride positive result

Answer 3

Pink/purple colour - phenol present

Question 4

Universal indicator colour for acid

Answer 4

Orange/red

Question 5

Universal indicator colour for alkali

Answer 5

Blue/purple

Question 6

Flame colour: lithium

Answer 6

Bright red

Question 7

Flame colour: sodium

Answer 7

Yellow

Question 8

Flame colour: potassium

Answer 8

Lilac

Question 9

Flame colour: calcium

Answer 9

Brick red

Question 10

Flame colour: barium

Answer 10

Apple green

Question 11

Flame colour: copper

Answer 11

Blue-green

Question 12

Solution/precipitate colour: copper hydroxide

Answer 12

Blue (P)

Question 13

Solution/precipitate colour: iron (II) hydroxide

Answer 13

‘Dirty’ green (P)

Question 14

Solution/precipitate colour: iron (III) hydroxide

Answer 14

Orange/brown (P)

Question 15

Solution/precipitate colour: lead iodide

Answer 15

Bright yellow (P)

Question 16

Solution/precipitate colour: silver chloride

Answer 16

White (P)

Question 17

Solution/precipitate colour: silver bromide

Answer 17

Cream (P)

Question 18

Solution/precipitate colour: silver iodide

Answer 18

Pale yellow (P)

Question 19

Solution/precipitate colour: barium sulfate

Answer 19

White (P)

Question 20

Solution/precipitate colour: copper sulfate

Answer 20

Blue (S)

Question 21

Solution/precipitate colour: titanium 3+

Answer 21

Purple (S) (A)

Question 22

Solution/precipitate colour: vanadium 2+

Answer 22

Purple (S)

Question 23

Solution/precipitate colour: vanadium 3+

Answer 23

Green (S)

Question 24

Solution/precipitate colour: vanadium 4+

Answer 24

Blue (S)

Question 25

Solution/precipitate colour: vanadium 5+

Answer 25

Yellow (S)

Question 26

Solution/precipitate colour: chromium 3+

Answer 26

Violet (S) (A)

Question 27

Solution/precipitate colour: manganese 2+

Answer 27

Pale pink (S) (A)

Question 28

Solution/precipitate colour: manganese 3+

Answer 28

Violet (S) (A)

Question 29

Solution/precipitate colour: cobalt 2+

Answer 29

Pink (S) (A)

Question 30

Solution/precipitate colour: nickel 2+

Answer 30

Green (S) (A)

Question 31

Solution/precipitate colour: chlorine

Answer 31

Pale green (S)

Question 32

Solution/precipitate colour: bromine

Answer 32

Orange/yellow (S)

Question 33

Solution/precipitate colour: iodine

Answer 33

Brown (S)

Question 34

Solution/precipitate colour in hexane: chlorine

Answer 34

Pale green (S)

Question 35

Solution/precipitate colour in hexane: bromine

Answer 35

Orange/brown/red (S)

Question 36

Solution/precipitate colour in hexane: iodine

Answer 36

Violet (S)

Question 37

Gas colour: fluorine

Answer 37

Pale yellow (A)

Question 38

Gas colour: chlorine

Answer 38

Green

Question 39

Gas colour: heated bromine

Answer 39

Red/brown

Question 40

Gas colour: heated iodine

Answer 40

Purple (sublimes from grey solid)

Question 41

Gas colour: nitric (II) oxide/NO

Answer 41

Colourless

Question 42

Gas colour: nitrogen (IV) dioxide/NO2

Answer 42

Brown

Question 43

Gas colour: dinitrogen oxide/N2O

Answer 43

Colourless

Question 44

Gas colour: ammonium chloride

Answer 44

White fumes (formed from NH3 + HCl)

Question 45

Test for nitrate (V) ions

Answer 45

Add NaOH and Devarda’s alloy (Cu/Al/Zn/)

Aluminium is a reducing agent, ammonia gas is evolved

Question 46

Test for ammonia gas

Answer 46

Characteristic choking smell, turns red litmus paper blue, forms white ammonia chloride fumes when in contact with HCl fumes