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A-Level Chemistry > Isomerism and carbonyl compounds > Flashcards

Isomerism and carbonyl compounds Flashcards

1
Q

What is optical isomerism?

A

It is a type of stereoisomerism.

Optical isomers are non-superimposable mirror images of each other.

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2
Q

What is stereoisomerism?

A

Stereoisomers have the same structural formula but different spatial arrangement of atoms.

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3
Q

What is a chiral carbon?

A

It is a carbon atom that has four different groups attached to it.

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4
Q

What is a racemate/racemic mixture?

A

A mixture of equal amounts of enantiomers.

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5
Q

How is a racemic mixture formed from a compound containing a carbonyl group?

A

The carbonyl is planar
There is an equal chance that a nucleophile will attack from either above or below.
This means that an equal amount of enantiomer will be formed.

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6
Q

How do you know if a compound is an optical isomer?

A

Optical isomers rotate plane polarised light.

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7
Q

Why is a racemate not optically active?

A

Both enantiomers would rotate plane polarised light in equal and opposite directions

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8
Q

What is produced when an aldehyde is oxidised?

A

Carboxylic acid

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9
Q

Which reagents can be used to distinguish between aldehydes and ketones?

A

Tollen’s reagent

Fehling’s solution

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10
Q

What is the observation when Tollen’s reagent is used to test for aldehydes and ketones?

A

Aldehyde- silver mirror formed

Ketone- no visible change

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11
Q

What is the observation when Fehling’s solution is used to test for aldehydes and ketones?

A

Aldehyde- brick red precipitate

Ketone- no visible change

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12
Q

What are the conditions for the reduction of aldehydes and ketones back to alcohols?

A

NaBH4

in water with methanol

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13
Q

What are the conditions to produce hydroxynitriles?

A

KCN

followed by dilute acid

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14
Q

What is formed when aldehydes and unsymmetrical ketones react with KCN followed by a dilute acid?

A

A mixture of enantiomers

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15
Q

Identify the hazards of working with KCN

A

it is an irritant
extremely dangerous if ingested or inhaled
it can react with moisture to produce hydrogen cyanide which is a highly toxic gas

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16
Q

How can risks be reduced when working with KCN?

A

wear gloves, a lab coat, safety goggles

perform the experiment in a fume cupboard

17
Q

What is the functional group of a carboxylic acid?

A

RCOOH

18
Q

What is a carboxylic acid?

A

It is a weak acid which slightly dissociates into a carboxylate ion and a H+ ion

19
Q

Give the reaction between carboxylic acids and carbonates

A

Carboxylic acid + carbonate → salt + carbon dioxide + water

20
Q

Give the name, conditions and reaction between carboxylic acids and alcohols

A

Esterification
heat, conc. sulfuric acid(catalyst)

carboxylic acid + alcohol ↔ ester + water

21
Q

What are the uses of esters?

A

food flavourings
perfumes
solvents
plasticisers

22
Q

Give the reaction and conditions for the acid hydrolysis of esters

A

reflux with a dilute acid e.g. HCl

ester + water ↔ carboxylic acid + alcohol

23
Q

Give the reaction and conditions for the base hydrolysis of esters

A

reflux with a dilute alkali such as NaOH

ester + OH- → carboxylate ion + alcohol

24
Q

What are vegetable oils and animal fats?

A

Esters of glycerol

25
Q

What are the properties of animal fats?

A

mainly saturated hydrocarbon chains

solid at room temperature

26
Q

What are the properties of vegetable oils?

A

unsaturated hydrocarbon chains

liquids at room temperature

27
Q

Give the reaction for the hydrolysis of oils and fats

A

Fats/oils + NaOH → glycerol + soap

28
Q

What is biodiesel?

A

A mixture of methyl esters of long chain carboxylic acids

29
Q

Give the reaction and conditions for the production of biodiesel

A

methanol, KOH(catalyst)

triester + methanol → glycerol + methylester

A-Level Chemistry (30 decks)

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