IB Chemistry HL 1.3.4 Biofuels Questions

Apply photosynthesis, fermentation, combustion enthalpy and sustainability evidence to compare biofuels and microbial fuel cells with fossil fuels.

Exam points

Write or identify the photosynthesis/fermentation relationship that supplies renewable organic fuel and explain the carbon-neutral cycle with a suitable equation.
Calculate energy efficiency from the enthalpies of combustion of reactants and products with correct stoichiometry, sign handling and units.
Compare ethanol, glucose, biodiesel or microbial fuel cells with fossil-fuel alternatives using physical properties, usability, sustainability and environmental evidence.

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

[Maximum number: 2]

Ethanol is a biofuel that can be mixed with gasoline.

Explain, including a suitable equation, why biofuels are considered to be carbon neutral.

biofuel raw material/sugar/glucose formed by photosynthesis

OR

biofuel raw material/sugar/glucose uses up carbon dioxide during its formation OR

biofuel from capturing gases due to decaying organic matter formed from photosynthesis

$6 \mathrm{CO}_{2}(\mathrm{~g})+6 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(\mathrm{aq})+6 \mathrm{O}_{2}(\mathrm{~g})$

Marking guidance:

Accept arguments based on material
coming from plant sources consuming
carbon dioxide/carbon for M1.

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IB Chemistry HL 1.3.4 Biofuels Questions question 1