WM Multiple Choice Questions

Question 1

The formation of ethene from the dehydration of ethanol can best be described as:

• an addition reaction
• an elimination reaction
• an oxidation reaction
• a substitution reaction

Answer 1

• an elimination reaction

Question 2

Which of these compounds is a secondary alcohol?

• ethane-1,2-diol
• 2-methylpentan-3-ol
• 2-methylpentan-2-ol
• methylpropan-1-ol

Answer 2

• 2-methylpentan-3-ol

Question 3

Which of these compounds could be oxidised to produce a carboxylic acid?

• CH₃CH₂CH₃
• CH₃CH₂(OH)CH₂CH₃
• CH₃CHO
• (CH₃)₂C(OH)CH₂CH₃

Answer 3

• CH₃CHO

Question 4

A compound has the empirical formula CH₂O. A mass spectrum of the compound features a molecular ion peak with an m/z ratio of 60. The infrared spectrum of the compound has no peaks above 3000 cm^–1.

What is the name of the compound?

• ethanal
• ethanoic acid
• ethyl ethanoate
• methyl methanoate

Answer 4

• methyl methanoate

Question 5

The mass spectrum of an organic compound sometimes contains a signal at one m/z unit higher than the molecular ion. Why is this?

• It is due to the presence of one atom of ²H.
• It is due to the association of a H atom to the molecular ion.
• It is due to the presence of one atom of ¹³C.
• It is due to removal of two electrons at the ionisation stage.

Answer 5

• It is due to the presence of one atom of ¹³C.

Question 6

Naturally occurring chlorine exists as two abundant isotopes.

How many molecular ion peaks would one expect to see in the mass spectrum of chloroform, CCl₃H?

• 1
• 2
• 3
• 4

Answer 6

• 4

Question 7

A mixture of propan-1-ol and methanoic acid is refluxed in the presence of concentrated sulfuric acid.

Which statement is true for this reaction?

• The ester formed is called propyl methanoate.
• It is an irreversible reaction.
• The mixture turns from orange to green.
• Hydrogen chloride is also formed.

Answer 7

• The ester formed is called propyl methanoate.

Question 8

A student wants to carry out the preparation of an ester, propyl ethanoate, under acidic conditions. The balanced equation for the reaction is shown below.

CH₃COOH_(aq) + CH₃CH₂CH₂OH_(aq) ⇌ H₂O_(l) + CH₃COOCH₂CH₂CH₃

The student carries out some tests on the reaction mixture and decides that the reaction had not gone to completion.

Which result provides proof that this is the case?

• The presence of a sharp peak around 1700 cm^–1 on the infrared.
• The presence of a single spot on a thin layer chromatography plate.
• The presence of three spots on a thin layer chromatography plate.
• The presence of a peak on the mass spectrum with an m/z ratio of 59.

Answer 8

• The presence of three spots on a thin layer chromatography plate.

Question 9

The alcohol butan-1-ol is heated with acidified sodium dichromate and the product distilled directly from the reaction mixture.

Which statement is not true of the reaction?

• The product is called butanal
• The product cannot be oxidised any further
• The product has a lower boiling point than the original alcohol
• The reaction mixture will change from orange to green

Answer 9

• The product cannot be oxidised any further

Question 10

Which of the following statements is/are true for 4-hydroxybenzoic acid, a precursor for the manufacture of aspirin?

1. The infrared spectrum will contain a broad peak at around 3000 cm^–1 and a sharp peak at around 1700 cm^–1.
2. The compound will turn purple in the presence of iron(III) chloride.
3. The compound will react with ethanoic anhydride to form an ester.

• 1,2 and 3
• Only 1 and 2
• Only 2 and 3
• Only 1

Answer 10

• 1,2 and 3