A-Level AQA Chemistry Oxidation, Reduction & Redox Equations: This question is about a glucose

This question is about a glucose–oxygen fuel cell - AQA - A-Level Chemistry - Question 11 - 2020 - Paper 1

Question 11

This question is about a glucose–oxygen fuel cell. When the cell operates, the glucose (C₆H₁₂O₆) molecules react with water at the negative electrode to form carbon... show full transcript

Worked Solution & Example Answer:This question is about a glucose–oxygen fuel cell - AQA - A-Level Chemistry - Question 11 - 2020 - Paper 1

Step 1

Deduce the half-equation for the reaction at the negative electrode.

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Answer

The half-equation for the reaction occurring at the negative electrode, where glucose reacts with water, is given by:

$C_6H_{12}O_6 + 6 H_2O \rightarrow 6 CO_2 + 24 H^+ + 24 e^-$

Step 2

Deduce the half-equation for the reaction at the positive electrode.

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Answer

The half-equation for the reaction at the positive electrode, where oxygen gas reacts with hydrogen ions, is:

$O_2 + 4 H^+ + 4 e^- \rightarrow 2 H_2O$

Step 3

Give the equation for the overall reaction that occurs in the Glucose–oxygen fuel cell.

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Answer

The overall equation for the reaction in a glucose–oxygen fuel cell is:

$C_6H_{12}O_6 + 6 O_2 \rightarrow 6 CO_2 + 6 H_2O$

Step 4

Give the conventional representation for the glucose–oxygen fuel cell.

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Answer

The conventional representation for the glucose–oxygen fuel cell is:

$[C_6H_{12}O_6 | H^+ | O_2 | H_2O | Pt]$

Step 5

State what must be done to maintain the EMF of this fuel cell when in use.

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Answer

To maintain the EMF of the fuel cell while in use, it is necessary to continually add reactants, such as glucose and oxygen, or to keep the concentration of reactants constant.

This question is about a glucose–oxygen fuel cell - AQA - A-Level Chemistry - Question 11 - 2020 - Paper 1

Worked Solution & Example Answer:This question is about a glucose–oxygen fuel cell - AQA - A-Level Chemistry - Question 11 - 2020 - Paper 1

Deduce the half-equation for the reaction at the negative electrode.

Deduce the half-equation for the reaction at the positive electrode.

Give the equation for the overall reaction that occurs in the Glucose–oxygen fuel cell.

Give the conventional representation for the glucose–oxygen fuel cell.

State what must be done to maintain the EMF of this fuel cell when in use.

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