Alkene
Add bromine water drop-wise at room temp. Positive test = decolourises bromine water.
Haloalkane
AgNO3, CH3CH2OH, warm. Positive test(s) = white (chloroalkane), cream (bromoalkane), yellow (iodoalkane) precipitate.
Carbonyl
2,4DNP. Positive test = orange precipitate.
Aldehyde
Tollen’s reagent, warm. Positive test = silver mirror.
Primary, secondary alcohol and aldehyde
K2Cr2O7, H+, warm. Positive test = colour change from orange to green.
Carboxylic acid
Na2CO3(aq). Positive test= effervescence.
Phenol
Two parts:
pH indicator/meter. Positive test = (pH<7).
Na2CO3. Positive test = no reaction
CO3 2-
Dilute nitric acid. Positive test = effervescence. Can be further tested by bubbling through limewater (turns milky).
SO4 2-
nitric acid (avoid false positive of carbonate)→ barium nitrate. Positive test = white precipitate.
Halide ions (X-)
HNO3, AgNO3. Positive test = white, cream or yellow precipitate.
Add dilute ammonia then concentrated ammonia. Chlorine precipitate dissolves in dilute, bromine precipitate dissolves in concentrated.
NH4+
NaOH(aq), heat. Positive test = damp red litmus paper turns blue.