Predictions from electrode potentials

Question 1

How do you determine if a reaction is feasible?

Answer 1

• The redox system with the positive e value will react from left to right and will gain electrons
• the redox system with the more negative e value will react from right to left, and lose electrons

Question 2

How do you determine which is the strongest oxidising agent?

Answer 2

• An oxidising agent takes away (gains) electrons away from the species and is reduced.
• These are the most positive

Question 3

How do you determine which is the strongest reducing agent?

Answer 3

• A reducing agent gives electrons to a species being reduced and is oxidised.
• These are the most negative

Question 4

What are the limitations to predicting whether a reaction is feasible?

Answer 4

1. Reaction rates
   The reaction rate may be very slow and even though a reaction is feasible, it may not occur
2. Concentration
   The reaction has concentrations of 1moldm-3, however the reaction may occur with dilute or concentrated solutions. Therefore the electrode potentials may be different from the standard values.
   - if the reaction is more concentrated, equillibria may shift to the right and the electrode potential will be less negative
   - if the reaction is more dilute, equillibria will shift to the left and increase the number of electrons and make the electrode potentials more positive
3. Other factors
   - may not occur at standard conditions, for example 100KPA and 298K
   - Electrode potentials only for aqueous equilibria