Revision:Tests for organic compounds

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Test for a carbonyl

• Reagents: 2,4-dinitrophenylhydrazine (2,4-DNPH)

• Observation with a positive test: Orange precipitate when added to a carbonyl

Test for an aldehyde

• Reagents: Fehlings solution 1 and 2

• Observation with a positive test: Red precipitate when reagents are warmed with an aldehyde

Test for an aldehyde

• Reagents: Tollen's reagent ( dilute ammonia solution)

• Observation with a positive test: Silver mirror with an aldehyde

Test for an alcohol

• Reagents: PCl₅ in dry conditions

• Observation with a positive test: Steamy fumes of HCl gas which turns damp blue litmus paper red

Test for a carboxylic acid

• Reagents: NaHCO_3(aq)

• Observation with a positive test: CO₂ gas which turns lime water milky

Test for an alcohol

• Reagents: Na

• Observation with a positive test: H₂ gas

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