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Chemical Tests
A2 Chemistry OCR…read more

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Bromine Water
Benzene ­ Will not react with bromine so there is
no colour change.
Phenol ­ Will polarize the bromine molecule
enabling it to react and decolourising the bromine
Cyclohexene ­ Will decolourise bromine water due
to the electron density in the C=C.…read more

Slide 3

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2,4-DNPH can detect aldehydes and ketones
2,4-DNPH + methanol + sulphuric acid = Brady's
Ketone/Aldehyde + Brady's = orange/yellow
precipitate due to C=O
Impure derivative can be filtered and recrystallised
Melting point can then be found
Then compared to a database to find which
aldehyde or ketone is present.…read more

Slide 4

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Tollens' Reagent
NaOH(aq)+AgNO3(aq) until brown precipitate formed
Then add dilute NH3(aq) until precipitate dissolves
Aldehyde- Silver mirror formed as it has reduced
the silver ions and been oxidised
Ketone- No reaction because it cannot be oxidised…read more


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