AQA A Level Chemistry

Topic Questions

8.3 Organic Chemistry Practicals (A Level only)

11 mark

Which of these statements about the recrystallisation of an organic solid is correct?

  • Recrystallisation decreases the purity of the solid

  • Recrystallisation lowers the melting point of the solid

  • Recrystallisation decreases the yield of an organic product

  • Recrystallisation is a chemical process

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21 mark

The preparation of organic liquids, such as some esters, can involve heating under reflux.

Which statement about heating under reflux is correct?

  • You can heat organic liquids without evaporation taking place

  • You can maintain organic liquids at their boiling point for extended periods

  • Heating is carried out indirectly using a water bath

  • The apparatus is closed to prevent the escape of materials

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31 mark

Which of the following can be done with the aid of a separating funnel?

 

Neutralise acidic impurities

Dry organic liquids

Separate miscible liquids

A

B

x

C

x

D

x

x

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41 mark

A mixture of ethanol, C2H5OH, ethanoic acid, CH3COOH, ethyl ethanoate,  CH3COOCH2CH3, and traces of water remains in a pear-shaped flask after heating under reflux for an hour.

If the mixture is then distilled, what is the order in which the products are likely to be collected in the distillate?

  • Ethyl ethanoate, ethanol, ethanoic acid

  • Ethyl ethanoate, ethanoic acid, ethanol

  • Ethanol, ethyl ethanoate, ethanoic acid

  • Ethanol, ethanoic acid, ethyl ethanoate

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51 mark

Which of the following is true about aldehydes and ketones?

  • Only aldehydes can be identified using Tollens’ reagent

  • Aldehydes and ketones can be identified using Tollens’ reagent

  • Aldehydes are positional isomers of ketones

  • Aldehydes are oxidising agents and ketones are reducing agents

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11 mark

A student attempts to purify an organic solid in the following way. The impure organic solid is dissolved in a hot solvent, cooled and allowed to recrystallise and filtered. The residue is washed in fresh solvent and dried.

Which of the following statements is true?

  • All the impurities have been removed in the process

  • The impurities remain in the residue

  • The impurities have a lower melting point that the pure organic solid

  • A hot filtration is necessary to remove all impurities

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21 mark

The following apparatus is used in organic chemistry preparations.

q2-8-3-mcq-hard-physical-chemistry-practicals

Which of the following reactions could be carried out using this apparatus?

  • C6H4(OH)COOH + CH3COOCOCH3

  • C6H5COOCH3 + H2SO4/HNO3

  • CH3CH2OH + Cr2O72- / H+

  • C6H6 + CH3COOCl

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31 mark

The following reaction sequence shows an organic synthesis pathway.

q3-8-3-mcq-hard-physical-chemistry-practicals

Which row correctly shows the reaction conditions of the three steps?

 

Step 1

Step 2

Step 3

A

UV light

Distillation

Heat under reflux

B

Room temperature

Heat under reflux

Distillation

C

UV light

Gentle warming

Heat under reflux

D

Room temperature

Heat under reflux

Heat under reflux

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41 mark

Which of these reactions will make a product that decolourises bromine water and also gives a silver mirror with Tollens’ reagent?

  • CH3CHCHCH2OH + [O] 

  • CH3CHCHCH2OH + [H] 

  • C6H5CH2OH +  [O] 

  • CH3CH2CH2CH2OH + Al2O3

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51 mark

This question refers to the following reaction scheme:

q5-8-3-mcq-hard-physical-chemistry-practicals

Which of the following reagents would not bring about the reaction indicated?

  • Step 1: aqueous NaOH

  • Step 2: aqueous acidified K2Cr2O7

  • Step 3: conc NaOH

  • Step 4: Al2O3

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11 mark

Which practical technique would be most suitable for purifying a sample of benzoic acid (mp = 122 oC)?

  • Buchner filtration

  • Recrystallisation 

  • Using a separating funnel

  • Simple distillation

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21 mark

Which of the following is not true about melting point tests?

  • The melting point tubes must be heated slowly

  • High melting point organic solids can decompose before melting

  • The solid must be totally dry and finely powdered

  • Impurities can lower or raise the melting point of organic solids

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31 mark

Which of the following reagents can you use to dry a damp sample of ethyl ethanoate?

  • saturated sodium carbonate solution

  • anhydrous sodium sulfate

  • concentrated sulfuric acid

  • aluminium oxide

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41 mark

Ibuprofen, paracetamol and aspirin can be identified by which laboratory technique(s)?

 

Column chromatography

TLC

Melting point test

A

B

x

C

x

D

x

x

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51 mark

When a Tollen’s test is carried out on propanal, what are the products of the reaction?

  • CH3CH3COOH + Ag

  • CH3CH3CH2OH + Ag

  • CH3CH3COOH + Ag+

  • CH3CH3CH2OH + Ag+

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