Hazard, risk and organic nomenclatureEdexcel International A Level Chemistry: Subtopic test

1. 1
   A technician is preparing a class practical in which students burn small samples of ethanol and hexane in spirit burners to compare the temperature rise of 100 cm³ of water. Hexane is highly flammable and its vapour can form an explosive mixture with air; ethanol is also flammable.

   (a)

   Which statement correctly distinguishes a hazard from a risk?

   [1 mark]

   • AA hazard is the chance that harm will happen; a risk is the substance that could cause harm
   • BA hazard is something with the potential to cause harm; a risk is the likelihood that the harm will occur in a particular situation
   • CA hazard and a risk are the same thing, but a risk is measured in a laboratory
   • DA hazard is the precaution taken to avoid harm; a risk is the harm that is caused

   (b)

   Which change would reduce the risk by using an alternative method involving a less hazardous substance?

   [1 mark]

   • AWearing safety goggles
   • BWorking in a fume cupboard
   • CBurning a smaller volume of hexane
   • DReplacing hexane with a less volatile, less flammable liquid alkane

   (c)

   Explain why a risk assessment should be carried out before the practical begins.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A stockroom list gives the structural formulae of four organic liquids: propan-1-ol, CH₃CH₂CH₂OH; butan-1-ol, CH₃CH₂CH₂CH₂OH; propanal, CH₃CH₂CHO; and propanoic acid, CH₃CH₂COOH.

   (a)

   Which two compounds in the list belong to the same homologous series?

   [1 mark]

   • APropan-1-ol and butan-1-ol
   • BPropan-1-ol and propanal
   • CPropanal and propanoic acid
   • DButan-1-ol and propanoic acid

   (b)

   Which functional group is present in propanal?

   [1 mark]

   • AHydroxyl, –OH
   • BCarboxyl, –COOH
   • CAldehyde, –CHO
   • DAlkene, C=C

   (c)

   Explain why propan-1-ol and butan-1-ol are members of the same homologous series.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A chemist is labelling unnamed bottles of organic compounds in a stockroom and must use IUPAC names and formulae, so that the compounds can be identified by anyone using the stockroom.

   (a)

   Give the IUPAC name of each of these compounds: (i) CH₃CH(CH₃)CH₂CH₃, (ii) CH₃CH₂CHBrCH₃, (iii) CH₃CH=CHCH₂CH₃.

   [3 marks]

   (b)

   Write the structural formula of each of these compounds: (i) 2,2-dimethylpropane, (ii) 1,2-dichloroethane, (iii) 3-methylbutan-1-ol, (iv) hex-3-ene.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A school science department plans a practical in which students burn methanol, ethanol, propan-1-ol and butan-1-ol in spirit burners under a beaker containing 100 cm³ of water, measuring the temperature rise for each. The alcohols are flammable and their vapours can ignite; methanol is also toxic. The plan states that each student will use about 50 cm³ of each alcohol, with a spirit burner on an open bench and no eye protection.

   (a)

   Explain the difference between a hazard and a risk, state why a risk assessment is carried out before the practical, and suggest how the risk in this practical could be reduced.

   [6 marks]

   (b)

   Explain what is meant by a homologous series and a functional group, using the four alcohols in the practical as your example, and explain why the results could be used to predict the result for pentan-1-ol.

   [6 marks]

   Total for question 4: 12 marks

End of questions