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Chemistry A level > 4.4 Aldehydes and Ketones > Flashcards

4.4 Aldehydes and Ketones Flashcards

1
Q

What is observed when Acidified potassium dichromate reacts with an aldehyde?

A

Orange to green

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2
Q

What is observed when Acidified potassium dichromate reacts with a ketone?

A

No observation

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3
Q

What is Observed when an aldehyde reacts with Acidified manganate?

A

Purple to colourless

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4
Q

What is Observed when a Ketone reacts with Acidified manganate?

A

No observation

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5
Q

Observation when tollens reagent is added to an aldehyde?

A

Silver precipitate formed

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6
Q

What is Observed when a ketone reacts with tollens reagent?

A

No observation

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7
Q

What is Tollens reagent?

A

Silver nitrate dissolved in ammonia

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8
Q

Observation of Fehling’s solution with an aldehyde?

A

Blue to brick red precipitate

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9
Q

Aldehyde and Fehling’s solution ion changes

A

Blue Cu2+ —> Brick red precipitate Cu2O

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10
Q

What is observed when Fehling’s solution and a ketone are mixed?

A

No Observation

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11
Q

Oxidising agents for Aldehydes?

A

*Fehling’s solution
*Acidified potassium dichromate (6)
*Tollens Reagent
*Acidified manganate (7)

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12
Q

What is 2,4 DNPH?

A

2,4 dinitrophenylhydrazine

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13
Q

What is observed when 2,4 DNPH reacts with an aldehyde or ketone?

A

Orange precipitate

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14
Q

What type of reaction occurs with an aldehyde and 2,4 DNPH?

A

Addition followed by elimination

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15
Q

What general group gives a positive reaction with iodoform?

A

methyl carbonyl group
CH3CO-R

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16
Q

Observation for positive iodoform test?

A

Yellow precipitate forms

17
Q

What compounds give positive iodoform tests?

A

Aldehydes
Ketones (2-ones)
Alcohols (2-ols)

18
Q

Why react HCN with alcohols

A

To increase carbon chain length

19
Q

HCN + Ethanol mechanism steps

A
  1. CN- attacks delta positive carbon
  2. Double bond oxygen breaks onto delta negative oxygen
  3. O- attracted to H+
20
Q

What reagent is used to reduce aldehydes and ketones?

A

Sodium boron tetrahydride
NaBH4

21
Q

Reagent for the iodoform test?

A

Iodine with sodium hydroxide (I2/NaOH)

Chemistry A level (18 decks)

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