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Date	May 2018	Marks available	2	Reference code	18M.3.sl.TZ1.11
Level	SL	Paper	3	Time zone	TZ1
Command term	Outline	Question number	11	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.i.

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

[1]

a.ii.

Outline why biofuels are considered more environmentally friendly, even though they produce more carbon dioxide per kJ of energy than petroleum based fuels.

[1]

b.

Markscheme

viscosity «of vegetable oils is too high»

transesterification

OR

«conversion into» alkyl/methyl/ethyl esters

[2 marks]

a.i.

R–CO–O–CH₃/RCOOMe

OR

R–CO–O–C₂H₅/RCOOEt

[1 mark]

a.ii.

«growing oil producing» plants absorbs carbon dioxide from the atmosphere

OR

«combustion of» petroleum based fuels releases carbon stored «for millions of years»

Accept “biofuels renewable” OR “petroleum based fuels non-renewable”.

Accept “waste vegetable oils can be converted to biofuels/biodiesel”.

Accept “biofuels do not contain sulfur”.

[1 mark]

b.

Examiners report

[N/A]

a.i.

[N/A]

a.ii.

[N/A]

b.

Syllabus sections

Options » C: Energy » C.4 Solar energy

Show 31 related questions

18M.3.sl.TZ1.11a.ii:
State the formula of a fuel that might be produced from the vegetable oil whose formula is shown.
18M.3.hl.TZ1.13b:
State the formula of a fuel that might be produced from the vegetable oil whose formula is shown.
16N.3.sl.TZ0.14a: State the equation for the complete transesterification of the triglyceride given below with...
18N.3.sl.TZ0.11c.ii: Describe how vegetable oils can be converted to a more suitable fuel.
18N.3.sl.TZ0.11c.i: State a physical property of vegetable oils that makes them very difficult to use as fuel in...
18N.3.sl.TZ0.11b: Light can be absorbed by chlorophyll and other pigments. Consider molecules A and B...
18N.3.hl.TZ0.14b.i: State a physical property of vegetable oils that makes them very difficult to use as fuel in...
18N.3.hl.TZ0.14b.ii: Describe how vegetable oils can be converted to a more suitable fuel.
17M.3.sl.TZ1.15d:
Determine the specific energy, in kJ $\,$ g⁻¹, and energy density, in kJ $\,$ cm⁻³, of a particular biodiesel using the following data and section 1 of the data booklet.

Density = 0.850 g $\,$ cm⁻³; Molar mass = 299 g $\,$ mol⁻¹;

Enthalpy of combustion = 12.0 MJ $\,$ mol⁻¹.
17N.3.sl.TZ0.15b: Vegetable oils are too viscous for use as liquid fuels. Describe, using an equation, how a...
18M.3.hl.TZ1.13a:
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.
17M.3.sl.TZ1.15b:
Deduce the formula of the biodiesel formed when the vegetable oil shown is reacted with the reagents in (a).
17N.3.sl.TZ0.15a: State the structural feature of chlorophyll that enables it to absorb visible light.
17M.3.sl.TZ2.12b:
Coloured molecules absorb sunlight. Identify the bonding characteristics of such molecules.
19M.3.hl.TZ1.17c:
Biodiesel containing ethanol can be made from renewable resources.

Suggest one environmental disadvantage of producing biodiesel from renewable resources.
19N.3.sl.TZ0.14a:
Write the equation for the complete combustion of ethanol.
16N.3.sl.TZ0.14b:
Outline why the fuel produced by the reaction in (a) is more suitable for use in diesel engines than vegetable oils.
18M.3.sl.TZ2.14b:
Outline why the ester product of this reaction is a better diesel fuel than pentyl octanoate.
19M.3.sl.TZ1.13c:
Biodiesel containing ethanol can be made from renewable resources.

Suggest one environmental disadvantage of producing biodiesel from renewable resources.
18M.3.sl.TZ2.14a:
Deduce the equation for the transesterification reaction of pentyl octanoate, C₇H₁₅COOC₅H₁₁, with methanol.
17M.3.sl.TZ1.15c:
Explain, in terms of the molecular structure, the critical difference in properties that makes biodiesel a more suitable liquid fuel than vegetable oil.
19N.3.sl.TZ0.14c:
Explain, including a suitable equation, why biofuels are considered to be carbon neutral.
19N.3.sl.TZ0.14d: State the type of reaction that occurs when ethanol reacts with vegetable oil to form biodiesel.
19M.3.sl.TZ2.12a:
The structure of chlorophyll is given in section 35 of the data booklet.

State the feature of the chlorophyll molecule that enables it to absorb light in the visible spectrum.
17M.3.sl.TZ1.15a:
State two reagents required to convert vegetable oil to biodiesel.
20N.3.sl.TZ0.9d:
A mixture of gasoline and ethanol is often used as a fuel. Suggest an advantage of such a mixture over the use of pure gasoline. Exclude any discussion of cost.
19M.3.sl.TZ2.12b:
Evaluate the use of biodiesel in place of diesel from crude oil.

Strength:

Limitation:
18M.3.sl.TZ1.11b:
Outline why biofuels are considered more environmentally friendly, even though they produce more carbon dioxide per kJ of energy than petroleum based fuels.
20N.3.hl.TZ0.11d: A mixture of gasoline and ethanol is often used as a fuel. Suggest an advantage of such a...
19M.3.hl.TZ2.17:
This question is about biofuel.

Evaluate the use of biodiesel in place of diesel from crude oil.
20N.3.sl.TZ0.9e: Contrast the molecular structures of biodiesel and the vegetable oil from which it is formed.

Hide related questions

Options » C: Energy