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Reactions of functional groups
9 MDCAT Chemistry questions with answers and explanations.
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A carboxylic acid reacts with an alcohol, in the presence of a little acid, to form:
- 1 An ether
- 2 An ester
- 3 An aldehyde
- 4 An alkane
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Correct answer: An ester
This reaction is called esterification, and water is also formed.
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Hydrolysis of an ester with sodium hydroxide solution is known as:
- 1 Esterification
- 2 Saponification
- 3 Hydrogenation
- 4 Polymerisation
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Correct answer: Saponification
Alkaline hydrolysis of an ester gives an alcohol and the sodium salt of the acid. It is the basis of soap making.
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Cold, dilute, alkaline potassium permanganate turns an alkene into a:
- 1 Diol
- 2 Ketone
- 3 Alkane
- 4 Haloalkane
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Correct answer: Diol
It adds two OH groups across the double bond and the purple colour fades.
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Bromoethane reacts with aqueous sodium hydroxide to give mainly:
- 1 Ethane
- 2 Ethanol
- 3 Ethene
- 4 Ethanal
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Correct answer: Ethanol
The hydroxide ion replaces bromine in a nucleophilic substitution reaction.
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Which type of alcohol is hardest to oxidise with acidified dichromate?
- 1 Primary
- 2 Secondary
- 3 Tertiary
- 4 All oxidise equally
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Correct answer: Tertiary
A tertiary alcohol has no hydrogen on the carbon carrying the OH group, so it resists oxidation.
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What is the functional group of an amine?
- 1 -NH2
- 2 -NO2
- 3 -CN
- 4 -COOH
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Correct answer: -NH2
Amines contain the amino group, -NH2, for primary amines.
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What is the name of CH3CONH2?
- 1 Ethanamine
- 2 Ethanamide
- 3 Ethanoic acid
- 4 Ethyl amine
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Correct answer: Ethanamide
It is an amide derived from ethanoic acid, so it is named ethanamide.
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Polythene is made by polymerising:
- 1 Ethane
- 2 Ethene
- 3 Propene
- 4 Ethyne
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Correct answer: Ethene
Ethene molecules join through their double bonds to form long chains of polythene.
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Which of these compounds gives a positive iodoform test?
- 1 Methanol
- 2 Propan-1-ol
- 3 Propanone
- 4 Ethanoic acid
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Correct answer: Propanone
The iodoform test is given by compounds containing a CH3-CO- group. Propanone has one.