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Chemistry OCR A A level > Carbonyls and Carboxylic Acids > Flashcards

Carbonyls and Carboxylic Acids Flashcards

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1
Q

Where is the functional group located in a carbonyl?

A

The end of the carbon chain

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2
Q

What can aldehydes be oxidised to?

A

Carboxylic acids when refluxed with acidified potassium dichromate

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3
Q

What can ketones be oxidised to?

A

Cannot be oxidised

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4
Q

What is the double bond made of in a ketone and an aldehyde?

A

A sigma bond and a pi bond

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5
Q

Is the C=O bond in carbonyl compounds polar or non-polar? Why?

A

Polar

Electron density in the double bond lies closer to the double bond

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6
Q

Why is a nucleophile attracted to a carbonyl?

A

Nucleophile is attracted to the slightly carbon atom

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7
Q

What chemical reduces an aldehyde and what is it reduced to?

A

Primary alcohols by NaBH4

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8
Q

What chemical reduces a ketone and what is it reduced to?

A

Secondary alcohols by NaBH4

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9
Q

Why is a carbonyl reacted with HCN?

A

Increase the length of the carbon chain

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10
Q

How is HCN formed for the reaction of carbonyls with HCN?

A

Sodium cyanide and sulfuric acid

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11
Q

What are the two steps usually associated with the addition to a carbonyl group?

A

Nucleophilic attack on the carbonyl group to form a negatively charged intermediate
Protonation of the intermediate to form an alcohol

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12
Q

What chemicals are present in the Brady’s reagent?

A

2,4- DNP
Methanol
Sulfuric Acid

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13
Q

What is formed when a carbonyl group is present in Brady’s reagent?

A

Yellow or orange precipitate

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14
Q

How can you identify between aldehyde or a ketone?

A

Tollens’ reagent

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15
Q

What is Tollens’ reagent made from?

A

A solution of silver nitrate in aqueous ammonia

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16
Q

How can you distinguish an aldehyde group?

A

A silver mirror

17
Q

Explain the chemistry of the Tollens’ test

A

Silver ions act as an oxidising agent in presence of ammonia
Silver ions are reduced to silver as aldehyde is oxidised to carboxylic acid

18
Q

Explain the solubility of carboxylic acids

A

Carboxylic acids with up to four carbons are soluble

Number of carbons increases the solubility decreases

19
Q

What type of acids are carboxylic acids?

A

Carboxylic acids are weak acids which means they partially dissociate in water

20
Q

How can you tell a redox reaction of carboxylic acid and metal is occurring?

A

Hydrogen gas
Carboxylate salt
Effervescence

Chemistry OCR A A level (20 decks)

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