Must learn these.
This is qualitative analysis.
Testing Phenol: Phenols acidic so can be tested using pH indicator paper. However phenols not
as acidic as carboxylic acid and do not react with sodium carbonate.
Or can add bromine at room temperature (electrophilic addition). Bromine decolourises and
white precipitate formed.
Testing Alkene: Add bromine water. Bromine water decolourises from orange to colourless.
Testing Haloalkane: Add silver nitrate and ethanol. Warm to 50C in water bath. Chloroalkaneswhite precipitate. Bromoalkane- cream ppt. Iodoalkanes- yellow ppt.
Testing Carbonyl: Add 2,4- dinitrophenylhydrazine, 2-4 DNP. Orange precipitate. No ppt = not
carbonyl.
Testing Aldehyde: Add Tollens’ reagent and warm. Silver mirror formed. Or Fehlings/ Benedict’s
solution used and brick red ppt forms in presence of aldehyde.
Testing Aldehyde and Primary/ Secondary Alcohol: Add acidified potassium dichromate (VI)
(H2SO4 and K2Cr2O7) and warm in water bath. Colour changes orange to green.
Testing Carboxylic Acid: Add aqueous sodium carbonate/ Hydrogencarbonate. Observe
effervescence, suggests reaction.
Testing Transition Metals: Aqueous sodium hydroxide produces precipitates with aqueous
transition metals.
No change = not the substance testing for.
‘Series of chemical test’- must talk about more than one.
If question says ‘confirm bottle is ketone’ when there are other substances, should test and
observations around ketone mostly.
