Tests for gases and ions

Question 1

Test for Hydrogen

H₂

Answer 1

Lit splint
Squeaky pop

Question 2

Test for Oxygen
O₂

Answer 2

Glowing splint

Relights

Question 3

Test for Water
H₂O

Answer 3

Anhydrous copper sulphate (CuSO₄)

Turns from white to blue

Question 4

Test for Carbon Dioxide

CO₂

Answer 4

Limewater

Turns cloudy

Question 5

Test for Ammonia
NH₃

Answer 5

Damp red litmus

Turns blue

Question 6

Test for Chlorine

Cl₂

Answer 6

Damp blue litmus

(Turns red &) bleaches

Question 7

Test for Lithium ions

Li⁺

Answer 7

Flame test

Red

Question 8

Test for Sodium ions

Na⁺

Answer 8

Flame test

Yellow

Question 9

Test for Potassium ions

K⁺

Answer 9

Flame test

Lilac

Question 10

Test for Calcium ions

Ca²⁺

Answer 10

Flame test

Orange/Red

Question 11

Test for Copper ions

Cu²⁺

Answer 11

Flame test

Blue/Green

OR

Sodium Hydroxide (NaOH)

Blue precipitate

Question 12

Test for Iron(II) ions

Fe²⁺

Answer 12

Sodium Hydroxide (NaOH)

Green precipitate

Question 13

Test for Iron(III) ions

Fe³⁺

Answer 13

Sodium Hydroxide (NaOH)

Brown precipitate

Question 14

Test for Ammonium ions

NH₄⁺

Answer 14

Sodium Hydroxide (NaOH)…
… then damp red litmus

Turns blue (tests for NH₃ gas)

Question 15

Test for Chloride ions

Cl^-

Answer 15

Nitric acid (HNO<sub>3</sub>)…
… then silver nitrate (AgNO<sub>3</sub>)

White precipitate

Question 16

Test for Bromide ions

Br^-

Answer 16

Nitric acid (HNO<sub>3</sub>)…
… then silver nitrate (AgNO<sub>3</sub>)

Cream precipitate

Question 17

Test for Iodide ions

I^-

Answer 17

Nitric acid (HNO<sub>3</sub>)…
… then silver nitrate (AgNO<sub>3</sub>)

Yellow precipitate

Question 18

Test for Carbonate ions

Co₃^2-

Answer 18

Dilute hydrochloric acid (HCL)…
… then limewater

Turns cloudy

Question 19

Test for Sulphate ions

SO₄^2-

Answer 19

Dilute hydrochloric acid (HCL)…
… then barium chloride (BaCl₂)

White precipitate

Question 20

Flame test

Answer 20

Dip nichrome wire into Hydrochloric acid (HCL)

Dip nichrome wire into sample

Place tip of wire into non-luminous bunsen flame

Observe colour of flame