GCE Chemistry Qualitative tests

CO₂

method: pass through limewater

positive result: colourless > milky ppt > colourless

H₂

method: burning splint in gas sample

Positive result: squeaky pop

O₂

method: place burning splint in gas sample

positive result: splint relights

Cl₂

method: universal indicator paper / litmus paper

positive result: bleaches

NH₃

method: glass rod dipped in conc HCl

positive result: dense white fumes (ui paper blue)

HCl

method: glass rod dipped in conc ammonia

positive result: dense white fumes (ui paper red)

Li⁺

method: dip nichrome wire in conc HCl, touch sample to wire, place in blue bunsen flame

positive result: crimson flame

Na⁺

method: dip nichrome wire in conc HCl, touch sample to wire, place in blue bunsen flame

positive result: orange flame

K⁺

method: dip nichrome wire in conc HCl, touch sample to wire, place in blue bunsen flame

positive result: lilac flame

Ca⁺

method: dip nichrome wire in conc HCl, touch sample to wire, place in blue bunsen flame

positive result: brick red flame

Ba⁺

method: dip nichrome wire in conc HCl, touch sample to wire, place in blue bunsen flame

positive result: green flame

Cu⁺

method: dip nichrome wire in conc HCl, touch sample to wire, place in blue bunsen flame

positive result: blue-green flame

Cl^-

method: add a few drops of dilute nitric acid, add a few cm³ of silver nitrate solution. Add dilute ammonia then conc ammonia

positive result: white ppt > dissolves

Br^-

method: add a few drops of dilute nitric acid, add a few cm³ of silver nitrate solution. Add dilute ammonia then conc ammonia

positive result: cream ppt > remains > dissolves

I^-

method: add a few drops of dilute nitric acid, add a few cm³ of silver nitrate solution. Add dilute ammonia then conc ammonia

positive result: yellow ppt > remains > remains

SO₄^2-

method: add dilute HCl, add a few cm³ of barium chloride

positive result: white ppt

CO₃^2-

method: add dilute acid

positive result: effervescence, solid disappears, gas produced: CO₂

NH₄⁺

method: add few cm³ of sodium hydroxide, warm gently

positive result: pungent gas evolved, damp ui paper turns blue, rod dipped in HCl produces white fumes