IB Chemistry SL Reactivity 1.3.4 Biofuels

Practise comparing fuels derived from recent biological carbon fixation with finite fossil resources. Evaluate renewability and lifecycle carbon, but also account for…

Exam points

explain renewability through biological growth and recent photosynthetic carbon fixation
compare lifecycle carbon or pollutant emissions with those from a fossil fuel
weigh land, food, processing and energy-density disadvantages against environmental benefits

[Maximum number: 1]

Gasoline (petrol), biodiesel and ethanol are fuels.

Table for Question 1.3.4—Biofuels question 1 — IB Chemistry SL

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.

Any one:

uses up fossil fuels more slowly

lower carbon footprint/ $\ce{CO2}$ emissions

undergoes more complete combustion

produces fewer particulates

higher octane number/rating

OR

less knocking

prevents fuel injection system build up

OR

helps keep engine clean

Marking guidance:

Accept an example of a suitable advantage even if repeated from 9c.

1 max

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1.3.4—Biofuels question 1