Page 30 - Fuel Cell Teacher Edition

Pre Lab

Que s tions

S ol utions

12. Why must we balance chemical equations with 16. Write the chemical reactions occurring at the anode,
coefficients? cathode and electrolyte of a zinc-air fuel cell.
If the chemical equation isn’t balanced, we Anode: Zn + 4 OH Zn(OH) + 2 e –
–
2–
4
violate the law of conservation of mass, and fail Cathode: 1/2 O + H O + 2 e 2 OH –
–
to predict quantity of products and reactants. 2 2
Electrolyte: Zn(OH) ZnO + H O + 2 OH –
2–
4 2
13. What are charged atoms?
17. Which direction does electrical current flow in a
Charged atoms, also called ions, have lost or fuel cell, anode to cathode, or cathode to anode?
gained an electron and thus have an electric Anode to cathode
charge. Anions have gained an electron and
are negatively charged. Cations are positively 18. Which electrode is positive and which is negative
charged and have lost an electron.
in a zinc-air fuel cell? Why?
14. What is a redox reaction? What happens during Anode – negative, because electrons are being
this reaction? generated at this electrode.
A redox reaction has both oxidation and Cathode – positive, because electrons are
reduction happening in the same reaction. being consumed at this electrode.
Oxidation is a loss of electrons and reduction is a
gaining of electrons.

15. In the following redox reaction, identify oxidation
and reduction.

Sodium is oxidized and hydroxide is reduced.

14 TOTAL REDOX™ – FUEL CELLS TOTAL REDOX™ – FUEL CELLS 15