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Date May 2018 Marks available 1 Reference code 18M.3.hl.TZ1.13
Level HL Paper 3 Time zone TZ1
Command term State Question number 13 Adapted from N/A

Question

One suggestion for the reduction of carbon footprints is the use of biofuels, such as vegetable oils, as a substitute for petroleum based fuels.

Outline the major technical problem affecting the direct use of vegetable oils as fuels in internal combustion engines and the chemical conversion that has overcome this.

[2]
a.

State the formula of a fuel that might be produced from the vegetable oil whose formula is shown.

                                                               M18/4/CHEMI/HP3/ENG/TZ1/13,b

[1]
b.

Markscheme

viscosity «of vegetable oils is too high»

 

transesterification

OR

«conversion into» alkyl/methyl/ethyl esters

 

[2 marks]

a.

R–CO–O–CH3 / RCOOMe

OR

R–CO–O–C2H5 / RCOOEt

[1 mark]

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Options » C: Energy » C.4 Solar energy
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