GCE Chemistry organic identification tests

colourless liquid with spirit/alcohol scent

possibly an alcohol/ethanol

colourless liquid with sharp, irritating scent

possibly a carboxylic acid/ethanoic acid

fruity/sweet/solvent-like scent

possibly an ester

add a few cm³ of deionised water to sample, solid or liquid, one layer forms, solid sample dissolves into colourless solution

polar liquid - possibly an alcohol, carboxylic acid, short carbon chain aldehyde or ketone

ionic copound / amino acid

add a few cm³ of deionised water to sample, solid or liquid, two layers form, solid does not dissolve

non polar liquid, not an ionic compound

place a few drops of the liquid on a watch glass, ignite, clean blue flame

low carbon content, possibly an alcohol

place a few drops of the liquid on a watch glass, ignite, sooty orange flame

high carbon content, possibly an alkane, alkene or long-chain alcohol

add a few cm³ of bromine water to the liquid / solution in a test tube, bromine water changes from orange to colourless

C=C / alkene present

add a few cm³ of bromine water to the liquid / solution in a test tube, bromine water remains orange

no C=C present

add 1cm³ of halogenoalkane to a few cm³ of ethanol, add silver nitrate solution, warm in water bath. white ppt, slow to form

chloroalkane

add 1cm³ of halogenoalkane to a few cm³ of ethanol, add silver nitrate solution, warm in water bath. cream ppt, forms at a medium rate

bromoalkane

add 1cm³ of halogenoalkane to a few cm³ of ethanol, add silver nitrate solution, warm in water bath. yellow ppt, fast to form

iodoalkane

add PCL₅ crystals to liquid, test gas released with glass rod dipped in conc NH₃ solution. gas released, misty fumes, solid dissapears, heat released, white smoke with NH₃ solution

OH group / COOH group present. HCl gas released

add PCL₅ crystals to liquid, test gas released with glass rod dipped in conc NH₃ solution. no gas released.

no OH group / COOH group present

mix acidified potassium dichromate (VI) and liquid / solution, warm in water bath. solution changes colour orange > green, change in smell

primary or secondary alcohol group / aldehyde. can be oxidised

mix acidified potassium dichromate (VI) and liquid / solution, warm in water bath. solution remains orange

tertiary alcohol group / ketone / other organic compoud that cannot be oxidised using acidified potassium dichromate (VI)

add solid Na₂CO₃ or NaHCO₃ to liquid, or add organic solid to Na₂CO₃ or NaHCO₃ solution. gas released, solid disappears, bubble gas through lime water and it chnages from colourless > milky

COOH group present, CO₂ gas released

add solid Na₂CO₃ or NaHCO₃ to liquid, or add organic solid to Na₂CO₃ or NaHCO₃ solution. no gas released

no COOH group present

add Mg ribbon to liquid, gas released, Mg disappears, test gas with lit splint - squeaky pop

COOH group present, H₂ gas released

add Mg ribbon to liquid, no gas released

no COOH group present

add liquid to 2,4-dinitrophenylhydrazine solution, yellow/orange precipitate

C=O group present, aldehyde or ketone

add liquid to 2,4-dinitrophenylhydrazine solution, no precipitate

no C=O group present, not an aldehyde or ketone

mix Fehling’s solution 1 & 2, add to liquid and warm in a water bath. blue solution changes to form red ppt

aldehyde / CHO group present

mix Fehling’s solution 1 & 2, add to liquid and warm in a water bath. solution remains blue

no CHO group present / ketone

mix liquid with ammonia and silver nitrate solution, warm in water bath. colourless solution changes to form silver mirror

aldehyde / CHO group present

mix liquid with ammonia and silver nitrate solution, warm in water bath. solution remains colourless

no CHO group present / ketone

mix solid / liquid with NaOH solution and warm, test any gas released with glass rod dipped in conc HCl. gas released, white smoke formed with conc HCl

Ammonia gas released from an amide

mix solid / liquid with NaOH solution and warm, test any gas released with glass rod dipped in conc HCl. no gas released

no ammonia released, substance is not an amide

mix conc HCl with NaNO₂ solution, wait for effervescence to stop, add to liqid / solution and warm in water bath. rapid effervescence.

NH₂ group present

mix conc HCl with NaNO₂ solution, wait for effervescence to stop, add to liqid / solution and warm in water bath. no effervescence.

no NH₂ group present

add a few cm³ of copper (II) sulfate to a solution of the solid. blue solution

glycine present

add a few cm³ of copper (II) sulfate to a solution of the solid. no change

no glycine present