Review
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Cu Electrochemistry 0.2M CuSO4 1M ZnSO4
Zn
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Predict the voltage that will be measured when activities are 1.0 Predict the voltage when [ZnSO4] is 0.010M
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What is the cathode and what is the anode? Represent the above electrochemical cell in n Is this an electrolytic or standard notation galvanic cell? What species is being Useful info: oxidized in each cell? Zn2+ + 2e- Zn(s) -0.763V Reduced? Cu2+ + 2e- Cu(s) +0.337V
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Demonstration The Human salt bridge
Zn(s) + Cu2+ Zn2+ + Cu(s) What is the purpose of a salt bridge?
Electrochemistry
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H2electrode reference electrode
Defined as 0.00V at all temperatures Solid calomel electrode also used as reference but its potential is 0.2444V relative to H2 By convention: Electrode potentials are written as reduction potentials
Example
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A Cu penny can be dissolved in nitric acid but not in hydrochloric acid. Using reduction potentials from the book, show why this is so. What are the products or expected products of each reaction?
Ion Selective Electrodes
pH electrodes
In solution to be external measured, ions diffuse through membrane until equilbrium is achieved, creates a build up of charge proportional to #H+ in external solution
pH electrodes
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Reference electrodes
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be in contact with ISE nAllows balancing of charge E = E0 + (2.303RT/ nF) x Log(A)
Differences between pH electrodes and other ISE
1. 2. 3. 4. 5. 6.
Schematic Diagram of ISE
Capillary Electrophoresis
a.k.a. CE, CZE, HPCE
Separation is based on differences in solute mobilities when a strong electric field is applied across a buffer
Advantages (Vs. HPLC)
1. 2. 3. 4. 5.
Velocity of Flow can be altered by:
1. 2. 3. 4.
Applications
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C...