Chemistry Electrode potentials question

In summary, the potential established at an electrode in a solution is given by E = E° - (R * T * log_e(Qsurface)), where E is the electrode potential, E° is the standard electrode potential, R is the gas constant, T is the temperature, and Qsurface is the reaction quotient at the electrode surface. Once equilibrium is reached, the potential remains steady and is given by Eeq = E° - (R * T * log_e(K)), where K is the equilibrium constant. The values of activities or concentrations at the electrode surface will be the same as in the bulk solution at equilibrium. If the system is held at a constant reaction quotient Qconstant, the potential established is Econstant = E° - (
  • #1
Big-Daddy
343
1
Am I right to think that the potential established at an electrode immediately when placed in solution is given by

[tex]E = E° - R \cdot T \cdot log_e(Q_{surface})[/tex]

where the potential E of the electrode results from the standard electrode potential (E°) of the reaction and the reaction quotient Qsurface at the electrode surface.

Then, once equilibrium is reached (usually fairly quickly for potential determining equilibria), we get a steady value of potential established, which is given by

[tex]E_{eq} = E° - R \cdot T \cdot log_e(K)[/tex]

Noting also that, once equilibrium conditions are established, the value of activities or concentrations at the electrode surface will be the same as their values in the bulk solution.

If the conditions of the system are held constant at a certain reaction quotient Qconstant instead of allowed to go to equilibrium, then the potential established is always

[tex]E_{constant} = E° - R \cdot T \cdot log_e(Q_{constant})[/tex]

Is this a correct understanding? And if this potential will be established on its own, is it correct to say that the only need for another electrode to join the first one is so that the difference in potentials can be measured (i.e. Ecell=E(Electrode 1)-E(Electrode 2))?
 
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  • #2
Small modification to all my equations above. Instead of

[tex]- R \cdot T [/tex]

I should have

[tex]- \frac{R \cdot T}{F} [/tex]

Where F is the Faraday constant.
 

Related to Chemistry Electrode potentials question

1. What is an electrode potential?

An electrode potential is the measure of how easily an electrode gains or loses electrons in a chemical reaction. It is a key concept in electrochemistry and is used to determine the direction and extent of a chemical reaction.

2. How is electrode potential measured?

Electrode potential is measured using a standard hydrogen electrode (SHE) as a reference. The potential difference between the SHE and the electrode of interest is measured using a voltmeter, and this is known as the standard electrode potential.

3. What factors affect electrode potential?

The factors that affect electrode potential include the nature of the electrode material, the concentration of ions in solution, and temperature. Other factors such as pH and pressure may also play a role.

4. How is electrode potential related to redox reactions?

Electrode potential is directly related to redox reactions as it determines the direction of electron flow in a chemical reaction. A positive electrode potential indicates that the electrode will gain electrons and undergo reduction, while a negative potential indicates the electrode will lose electrons and undergo oxidation.

5. Why is electrode potential important in practical applications?

Electrode potential is important in practical applications because it can be used to predict and control the direction and extent of chemical reactions. It is also used in electrochemical cells, batteries, and other devices that rely on redox reactions for energy conversion.

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