Electrochemistry

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Electrochemistry

• Kristin Shepard
• Brooke Petersen

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Electrochemical Cells- Terms

• Electrode- Any cell that is used to conduct
  electricity Where the reaction actually takes
  place- Solid Part
• Anode- Solid where the oxidizing happens
• Cathode- Solid where the reduction occurs
• Current- The flow of electrons- Electricity
• Salt Bridge- Concentrated salt solution with ions
  that will not react with solutions

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Standard Cell Potential

• Standard Cell Potential is known as E
• There are four simple steps
• Even the electrons
• Flip the most negative equation
• Add the equations
• Add the E

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Calculating ?G

• To calculate this, we use the following equation
  when all substances are at standard conditions
• ?G -nFE

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Calculating K

• After finding the ?G, we can now find K using
• ?G -RTlnK

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How many mols of Pt may be deposited on the
cathode when 0.80 F of electricity is passed
through a 1.0 M solution of PT4 ?

• 1.0 mol
• 0.60 mol
• 0.20 mol
• 0.80 mol
• 0.40 mol

It takes 4 mol of electrons (4F) to change the
platinum ions to platinum metal. The calculation
would be (0.80)(1 mol Pt/4 F) 0.20 mol Pt.
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What happens to the cell voltage when the copper
electrode is made smaller?

• There is no change in the voltage.
• The voltage becomes zero.
• The voltage increases.
• The voltage decreases, but stays positive.
• The voltage becomes negative.

The size of the electrode is not important.
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What happens to the cell voltage after the cell
has operated for 10 minutes?

• There is no change in the voltage.
• The voltage becomes zero.
• The voltage increases.
• The voltage decreases, but stays positive.
• The voltage becomes negative.

As the cell operates, the copper ion
concentration would decrease and the zinc ion
concentration would increase. Both of these
changes would make the logarithm term in the
Nernst equation more negative. This would
decrease the voltage.