Chemical tests

Chemical tests

1. Inorganic

   • Flame test
     • Na+
       • Yellow flame
     • Li+
       • Crimson red flame
     • Ca2+
       • Brick red flame
     • K+
       • Lilac flame
     • Cu2+
       • Green/Blue flame
     • Ba2+
       • Pale green
     • Mg2+
       • No colour
   • Transition metals
     • Complex ion colours
       • Cobalt (Co2+)
         • [Co(H20)6]2+
           • Pale pink
         • Conc HCl
           • [CoCl4] 2-
             • Blue solution
         • OH-
           • [Co(OH)2(H20)4]
             • Blue ppt soluble in excess NaOH
       • Copper (Cu2+)
         • [Cu(H20)6] 2+
           • Blue solution
         • Excess NH3
           • [Cu(NH3)4 (H20)2] 2+
             • Royal blue solution
         • Excess Cl-
           • [CuCl4] 2-
             • Yellow solution
         • OH-
           • [Cu(OH)2 (H20)4]
             • Pale blue ppt insoluble in excess OH
       • Iron (II)
         • [Fe(H20)6] 2+
           • Pale green solution
         • OH-
           • [Fe(OH)2(H20)4]
             • Dirty green ppt
           • Excess
             • Re-dissolves to Fe(OH)2+ which is unstable and oxidises in air to a rusty brown ppt of Fe(OH)3
       • Iron (III)
         • [Fe(H20)6] 3+
           • Yellow-green solution
       • Chromium (Cr3+)
         • [Cr(H20)6] 3+
           • Violet solution
         • OH-
           • (Cr(OH)3(H20)3]
             • Green ppt soluble in excess
         • CrO4 2-
           • yellow chromate ion
         • Cr2O7-
           • Orange dichromate ion
     • MnO4-
       • Purple ion
   • P block
     • Group 7- Halogens
       • Fluorine (F-)
         • Room temp
           • yellow gas
       • Chlorine (Cl-)
         • Room temp
           • Green gas
         • Nitric acid + silver nitrate
           • White ppt
             • Soluble in dilute + conc NH3
         • Conc H2SO4
           • Misty fumes
             • HCl
       • Iodine (I-)
         • Room temp
           • Grey solid
         • Nitric acid + silver nitrate
           • Yellow ppt
             • Insoluble in dilute NH3
         • Conc H2SO4
           • Misty fumes
             • HI
           • Purple vapour
             • I2
           • colourless gas
             • SO2
           • Yellow solid
             • S
           • bad egg smell
             • H2S
       • Bromine (Br-)
         • Room temp
           • Red-Brown liquid
         • Nitric acid + Silver nitrate
           • Cream ppt
             • Insoluble in dilute NH3, soluble in conc
         • conc H2SO4
           • Misty fumes
             • HBr
           • Brown vapour
             • Br2
           • colourless gas
             • SO2
   • Cations
     • NaOH
       • Mg 2+, Zn 2+, Al 3+, Pb 3+
         • White ppt
           • AL 3+ dissolves in excess NaOH
           • Zn 2+ dissolves in excess NH3
           • Potassium Iodide produces a yellow ppt with Pb 3+
   • Anions
     • Barium chloride/barium nitrate
       • White ppt with carboinates, sulfites and sulfates
         • dilute HCl
           • Effervescence with carbonates
           • sulfur dioxide formed from sulfites
           • no reaction with sulfate

2. Organic

   • Phenol
     • Add Br2
       • 2,4,6 tribromophenol
       • Antiseptic smell
       • White ppt
     • Add FeCl3
       • Violet solution
   • Aldehyde
     • Tollen's reagent
       • Silver mirror
     • Fehling's
       • Orange/red ppt of Cu+
   • Alcohol
     • Acidified potassium dichromate
       • Tertiary alcohol
         • no visible change, as tertiary alcohols cannot be oxidised
       • Primary and secondary
         • Orange to green colour change
         • primary oxidised to aldehyde then carboxylic acid
         • Secondary oxidised to ketone
     • Lucas test
       • Zinc chloride + conc HCl
         • Primary alcohol
           • No reaction at room temp
         • Secondary alcohol
           • Layers formed after 5 minutes
         • Tertiary alcohol
           • Layers form immediately
     • Iodoform
       • NaNO2 + I2
       • Potitive test
         • Ethanol
         • Secondary alcohol with a CH3 attatched with C with OH
   • Carbonyls
     • 2,4 DNPH
       • Orange ppt formed
         • Can be purified and removed by suction filtration.
           • melting point test and compare with known literature values
             • Can identify aldehyde or ketone
   • Halogenoalkanes
     • Hydrolysis with NaOH
       • Nitric acid to remove unwanted ions
         • Silver nitrate
           • Cl-
           • Br-
           • I-
   • Alkene
     • Bromine water
       • Brown to colourless
   • Carboxylic acids
     • Na2CO3 or NaHCO3
       • Effervescence
       • Turns limewater cloudy
   • Ketones
     • Iodoform
       • NaOH + I2
       • Positive test for methyl ketones
         • Yellow ppt
         • Antiseptic smell
   • Esters
     • No chemical test but sweet smelling
   • Acyl chlorides
     • Add water
       • Misty fumes of HCl
   • Amines and amides
     • Add NaOH and warm
       • Fishy odour + turns damp red litmus blue
         • Ammonia released
     • Primary amine
       • Add HNO2
         • N2 gas released and effervescence is observed