IB Chemistry SL 1.3.4 Biofuels Questions

Use real exam questions to write fermentation equations, calculate biofuel efficiency and evaluate renewable fuels against alternatives.

Exam points

Write the balanced fermentation equation for glucose to ethanol and carbon dioxide, and relate biofuel carbon to biological carbon fixation where the equation is requested.
Calculate or interpret energy efficiency from the enthalpies of combustion of reactants and products, using consistent stoichiometry and units.
Evaluate biofuels against alternatives using supported volatility, usability, renewable/carbon-footprint and environmental advantage or disadvantage evidence rather than energy density alone.

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Study 1.3.4—Biofuels conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

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Gasoline (petrol), biodiesel and ethanol are fuels.

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