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Alcohols and Carboxylic Acids

Fermentation and the distillation of ethanol

  • 3 things to know
  • Components 1 and 2

Overview

Temperature normally used for fermentation, raw materials from which glucose for fermentation is usually obtained and boiling temperature of ethanol and of water.

What you need to know

Answer each one before you reveal it.

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Key term

What organism and what temperature does fermentation use, and why is neither a much higher nor a much lower temperature chosen?

Key term

Write the equation for the fermentation of glucose.

Key term

Name the organism used in fermentation and the type of substance within it that catalyses the reaction.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Write the equation for the fermentation of glucose.

    Model answer

    C₆H₁₂O₆(aq) → 2C₂H₅OH(aq) + 2CO₂(g).

  2. 2

    Name the organism used in fermentation and the type of substance within it that catalyses the reaction.

    Model answer

    Yeast is used, and enzymes within it catalyse the reaction.

  3. 3

    State the temperature normally used for fermentation.

    Model answer

    A temperature of about 35 °C is used.

  4. 4

    Explain why fermentation is not carried out at a much higher temperature.

    Model answer

    The enzymes in the yeast would be denatured, so they would lose their shape and stop working.

  5. 5

    Explain why fermentation is not carried out at a much lower temperature.

    Model answer

    The rate would be far too slow to be practical, because the enzyme-catalysed reactions slow down as the temperature falls.

  6. 6

    Why must fermentation be carried out in the absence of air?

    Model answer

    Oxygen would allow the ethanol to be oxidised to ethanoic acid, spoiling the product.

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