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Ch.19 - Electrochemistry
Chapter 19, Problem 19.67

How are standard reduction potentials defined?

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Standard reduction potentials are defined as the voltage associated with a reduction reaction at an electrode when all solutes are at a concentration of 1 M, all gases are at a pressure of 1 atm, and the temperature is 25°C (298 K).
These potentials are measured under standard conditions and are used to predict the direction of electron flow in electrochemical cells.
The standard reduction potential is denoted by E° and is measured in volts (V).
A positive E° value indicates a greater tendency for the species to gain electrons and be reduced, while a negative E° value indicates a lesser tendency.
Standard reduction potentials are typically listed in tables, with the reduction of hydrogen ions to hydrogen gas (2H⁺ + 2e⁻ → H₂) assigned a potential of 0.00 V as a reference point.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Standard Reduction Potential

Standard reduction potential (E°) is a measure of the tendency of a chemical species to gain electrons and be reduced. It is defined under standard conditions (1 M concentration, 1 atm pressure, and 25°C) and is measured in volts. A higher E° value indicates a greater likelihood of reduction occurring, making it a crucial parameter in electrochemistry.
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Standard Reduction Potentials

Electrochemical Cells

Electrochemical cells are devices that convert chemical energy into electrical energy through redox reactions. They consist of two electrodes: an anode (where oxidation occurs) and a cathode (where reduction occurs). The standard reduction potentials of the half-reactions at these electrodes determine the overall cell potential and the direction of electron flow.
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Nernst Equation

The Nernst equation relates the standard reduction potential of a half-cell to the concentrations of the reactants and products involved in the redox reaction. It allows for the calculation of the cell potential under non-standard conditions, providing insight into how changes in concentration affect the driving force of the reaction.
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