exam specific answers (alcohols)
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what would you write for a 6 mark question asking about the mistakes with the apparatus for the distillation of an alcohol?
• anti-bumping granules * no anti-bumping granules so need to add them * to create smaller bubbles/prevent mixture jumping into condenser • open system with no thermometer * system should be closed above flask to prevent gases escaping * should be closed with bung and thermometer * to prevent distillation of other components/stay in suitable temperature range • water direction in condenser * water flows in wrong direction through condenser * condenser not cool enough * product may not condense
state two advantages and two disadvantages of producing ethanol by the fermentation method compared to the direct hydration method from ethene. (4)
advantages: * lower temperature and pressure * less use of non-renewable fossil fuels disadvantages: * low atom economy * uses land for sugar crops so it isn’t available for food crops
Bioethanol is used as an alternative to fossil fuels. This statement appeared on a website. “The fact that bioethanol is a carbon-neutral fuel outweighs the environmental disadvantages of producing bioethanol.” Evaluate this statement. In your answer you should include: * an outline of how bioethanol is produced * relevant equations * analysis of the environmental impacts. (6)
• photosynthesis is natural process in plants which takes CO2 from air • fermentation is process used to make bioethanol releasing some CO2 • combustion is process where bioethanol is burned and releases some CO2 • 6CO2 + 6H2O → C6H12O6 + 6O2 • C6H12O6 → 2C2H5OH + 2CO2 • 2C2H5OH + 6O2 → 6H2O + 4CO2 • producing bioethanol causes deforestation and sacrifices land which could be used for food • causes loss of biodiversity • although 6 CO2 in and 6 CO2 out isn’t actually carbon neutral because fuel is used in production and distribution