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WorksheetsPost Lab Exp 6
Total questions: 10
Worksheet time: 8mins
An organic compound X has the following chemical properties.
· Forms a yellow precipitate when tested with 2,4-dinitrophenylhydrazine.
· Forms a yellow precipitate when it reacts with an excess iodine in alkaline solution.
Which of the following compounds is X?
Which substance would test positively with 2,4-DNPH but negatively with Tollens’ reagent?
Propanal
Propanone
Propanoic acid
1-propanol
The only aldehyde that gives positive result with I2/NaOH is
Butanal
2-methylpropanal
Ethanal
Propanal
What is the reagent to differentiate between a benzaldehyde and a ketone
Lucas reagent, conc. HCl, ZnCl2
Tollens' reagent, [Ag(NH3)2]+, OH-
Brady's reagent, 2,4-DNPH
Bromine test, Br2, CH2Cl2
Which structural formula is of 2,4-DNPH, a reagent to confirm the presence of carbonyl group.
A
B
C
D
What is the observation made when 3-methylbutanone reacted with Tollens' test
pale yellow does not formed
yellow precipitate does not formed
silver mirror does not formed
cloudiness or two layer does not formed
Unknown Y reacts with the tests below :
2,4-DNPH : orange precipitate formed
Fehling's reagent : no change
Tollen's reagent : no change
Iodoform test : yellow precipitate formed
Which of the compound below is unknown Y?
ethanal
benzaldehyde
propanone
Which of the compound below is optically active and gives yellow precipitate with iodine in alkaline solution?
1. Fehling's test: No observable change
2. Tollen's test: No observable change
Which carbonyl compound will have the above observations?
CH3CH2CHO
C6H5CHO
CH3CH2COCH3
CH3COOH
When aldehyde is heated with Fehling's solution, it gives a precipitate of
Cu2O
CuO
Cu2O & CuO
Cu
