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Cell Potentials at Standard Conditions. Revisiting E cell. Standard Reduction Potentials. Reduction potentials for many electrodes have been measured and tabulated. Standard Hydrogen Electrode. Their values are referenced to a s tandard h ydrogen e lectrode ( SHE ). - PowerPoint PPT Presentation
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Cell Potentials at Standard Conditions
Revisiting Ecell
Standard Reduction Potentials
Reduction potentials for
many electrodes have been
measured and tabulated.
Standard Hydrogen Electrode• Their values are referenced to a standard hydrogen
electrode (SHE).• By definition, the reduction potential for hydrogen is
0 V: 2 H+ (aq, 1M) + 2 e− H2 (g, 1 atm)
Standard Cell PotentialsThe cell potential at standard conditions can be found through this equation:
Ecell = Ered (cathode) − Ered (anode)
Because cell potential is based on the potential energy per unit of charge, it is an intensive property.
Sample Exercise 20.5 p.841
Ecell = Ered (cathode) − Ered
(anode)
TREND ALERT!The more the , the greater the tendency for reduction under std conditions.
Ered
Oxidizing and Reducing Agents
F2: Most + value, easily reduced, strongest oxidizing agent
Li: Most – value, easily oxidized, strongest reducing agent
Oxidizing and Reducing Agents p. 843
• The strongest oxidizers have the most positive reduction potentials.
• The strongest reducers have the most negative reduction potentials.
Oxidizing and Reducing Agents
The greater the difference between the two, the greater the voltage of the cell.
Sample Exercise 20.8 p. 845
WEAKEST …………………………………STRONGEST
NO3- = + 0.96 V Ag+ = +0.80 V Cr2O7
-2 = +1.33 V
Ag+ NO3-
Cr2O7-2