Chemical Tests

Li⁺

• flame test

• red flame

K⁺

• flame test

• lilac flame

Na⁺

• flame test

• yellow flame

Cu²⁺

• flame test

• blue/green flame

Ca²⁺

• flame test

• orange/red flame

Fe²⁺

• add NaOH (aq)

• green precipitate

Fe³⁺

• add NaOH (aq)

• red/brown precipitate

Cu²⁺

• add NaOH (aq)

• blue precipitate

NH₄⁺

• add NaOH and warm

• test gas evolved with damp red litmus paper

• paper turns blue

Cl^-

• add HNO₃ 

• add AgNO₃

• (acidified silver nitrate)

• white precipitate

Br^-

• add HNO₃ 

• add AgNO₃

• (acidified silver nitrate)

• cream precipitate

I^-

• add HNO₃ 

• add AgNO₃

• (acidified silver nitrate)

• yellow precipitate

SO₄^2-

• add HCl

• add BaCl₂

• (add acidified barium chloride)

• white precipitate

CO₃^2-

• add acid

• bubble the gas formed through limewater

• fizzing

• limewater goes cloudy

Fe²⁺ test equation

Fe²⁺ (aq) + 2OH^- (aq) → Fe(OH)₂ (s)

Fe³⁺ test equation

Fe³⁺ (aq) + 3OH^- (aq) → Fe(OH)₃ (s)

Cu²⁺

Cu²⁺ (aq) + 2OH^- (aq) → Cu(OH)₂ (s)

NH₄ test equation

NH₄⁺ (aq) + OH^- (aq) → NH₃ (g) + H₂O (l)

Cl^- test equation

Ag⁺ (aq) + Cl^- (aq) → AgCl (s)

Br^- test equation

Ag⁺ (aq) + Br^- (aq) → AgBr (s)

I^- test equation

Ag⁺ (aq) + I^- (aq) → AgI (s)

SO₄^2- test equation

Ba²⁺ (aq) + SO₄^2- (aq) → BaSO₄ (s)

CO₃^2- test equation

CO₃^2- (aq) + 2H⁺ (aq) → CO₂ (g) + H₂O (l)

H₂

• place a lit splint into the gas

• hear a squeaky pop

O₂

• place a glowing splint into the gas

• the splint relights

CO₂

• bubble the gas through limewater (Ca(OH)₂)

• the limewater turns cloudy

NH₃

• place damp red litmus paper into the gas

• the paper turns blue

Cl₂

• place damp blue litmus paper into the gas

• (paper turns red)

• then bleaches/ turns white

H₂O

• add anhydrous copper sulfate (CuSO₄.5H₂O (s))

• turns blue

H₂ test equation

H₂ + ½O₂ → H₂O
(you hear the sound of this reaction)