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A Level Chemistry > 3.7 Optical Isomerism & 3.8 Aldehydes And Ketones > Flashcards

3.7 Optical Isomerism & 3.8 Aldehydes And Ketones Flashcards

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1
Q

Name Compound CH3C(OH)(CN)CH2CH2CH3

A

2-hydroxy-2-methylpentanenitrile

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2
Q

How to distinguish between enantiomers

A
  • Use of plane polarised light
  • light rotated in oppose directions equally
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3
Q

Name compound CNCH(OH)CH2CH3

A

2-hydroxybutan-1-enitrile

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4
Q

What type of product is formed when an aldehyde is reduced?

A

primary alcohol

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5
Q

What is the definition of stereoisomerism?

A

molecules with the same structural formula but different arrangement of atoms in space

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6
Q

What are optical isomers?

A

non-superimposable mirror images

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7
Q

What do chiral molecules do to plane-polarised light?

A

rotate it

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8
Q

What forms when an unsymmetrical ketone reacts with KCN?

A

A mixture of enantiomers

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9
Q

Why are racemic mixtures optically inactive?

A

They contain equal amounts of enantiomers which cancel out the optical activity

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10
Q

What is the definition of structural isomerism?

A

molecules with the same molecular formula but different structural formulae

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11
Q

What forms when a ketone reacts with HCN?

A

Hydroxynitrile

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12
Q

What is another name of a chiral centre

A

sterogenic centre

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13
Q

What is a chiral carbon

A

carbon atom bonded to 4 different groups

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14
Q

Name product formed when pentanal is reduced with NaBH4

A

pentan-1-ol

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15
Q

What is meant by a sample which is enantiomerically pure

A

sample which only contains one optical isomer

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16
Q

What is the nucleophile in the reaction of aldehydes with NaBH4

A

H^-

17
Q

Why are racemic mixtures optically inactive

A

They contain equal amounts of enantiomers which cancel out the optical activity

18
Q

What is the effect of enantiomers on plane polarised light

A

They rotate the plane of polarised light

19
Q

Name product formed when butanal is reacted with KCN

A

2-hydroxypentanenitrile

20
Q

What is observed when Fehlings reagent is mixed with an aldehyde

A

brick-red precipitate forms

21
Q

What is another name for a racemix mixture

A

Racemate

22
Q

Name product formed when butanone is reduced with NaBH4

A

butan-2-ol

23
Q

Condition needed in reduction of an aldehyde or ketone

A

acidic solvent

24
Q

What are enantiomers

A

Non-superimposable mirror images

25
Q

What is a racemic mixture

A

a mixture which contains equal amount of enantiomers

26
Q

What is the hazard of using KCN

A

it is highly toxic

27
Q

State the relationship between two chiral molecules with the same structural formula.

A

non-superimposable mirror images

28
Q

Which compound does not show stereoisomerism?
a.
1,2-dichloropropane
b.
1,3-dichloropropene
c.
1,2-dichloropropene
d.
1,3-dichloropropane

A

d

29
Q

Give the chemical formula of the reagent used to test for Ba^2+ and the observation made.

A

reagent : H2SO4
observation : white precipitate formed

30
Q

Give the chemical formula of the reagent used to test for the SO4^2- and the observation made.

A

reagent : BaCl2
Observation : white precipitate

31
Q

Which one of the following statements about but-2-enal, CH3CH=CHCHO, is not true?
A It has stereoisomers.
B It shows a strong absorption in the infra-red at about 1700 cm−1.
C It will turn an acidified solution of potassium dichromate(VI) green.
D It can be dehydrated by concentrated sulphuric acid.

A

D

32
Q

Which one of the following reactions will produce an organic compound that has optical isomers?
A dehydration of butan-2-ol by heating with concentrated sulphuric acid
B reduction of pentan-3-one by warming with NaBH4
C addition of Br2 to 3-bromopropene
D reduction of 2,3-dimethylpent-2-ene with H2 in the presence of a nickel catalyst

A

D

33
Q

In which one of the following mixtures does a redox reaction occur?
A ethanal and Tollens’ reagent
B ethanoyl chloride and ethanol
C ethanal and hydrogen cyanide
D ethanoic acid and sodium hydroxide

A

A
because in silver mirror there is an Ag^+ ion (fehlings has Cu^2+ ion) As Ag+ goes to Ag
ethanal therefore gets oxidised as Ag gets reduced

34
Q

What reagent is used to reduce an aldehyde or a ketone

A

NaBH4

A Level Chemistry (5 decks)

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