An electrochemistry question

In summary, the conversation discusses the reaction Mn2+ + 2 H2O - MnO2 + 4 H+ + 2 e− (−1.22 V) and questions why the formation of MnO2 needs to be done in anodic potential despite the standard potential being negative. It is explained that the negative half-reaction potential indicates that the reaction is not spontaneous and requires external energy to occur. The conversation then moves on to discuss the three electrode system and how the deposition of MnO2 and metallic Cr will occur on positive and negative potentials, respectively. The main question is why the deposition of MnO2 is not done in the negative potential range, considering both half-reactions are non-spontaneous and
  • #1
angela2007
3
0
Mn2+ + 2 H2O - MnO2 + 4 H+ + 2 e− ( −1.22 V), this reaction is acucurate. the standard potential is negative, then why all the work for the formation of MnO2 need to be done in anodic potential?
 
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  • #2
According to what you wrote for the reaction (interpreting for one wrong "-" symbol, needs to be an arrow), the half-reaction is an oxidation and requires energy in order to occur. The negative half-reaction potential tells you that the half reaction is not spontaneous and so requires energy to be supplied.
 
  • #3
my question is in three electrode system: working electrode, Pt counter electrode, and Ag/AgCl reference electrode.
for example, Mn2+ + 2 H2O -MnO2 + 4 H+ + 2 e− ( −1.22 V), the deposition of Mno2 will be accomplished on postive potential. Cr3+ +3e- Cr ( −0.74 V), the depsotion of metallic Cr will be accomplished on negative potential.
I Know for both the half-reactions, they are non-spontaneous and need external electric energy. My point is why the deposition of Mno2 is not done in negative potential range.
 

1. What is electrochemistry?

Electrochemistry is the branch of chemistry that studies the relationship between electricity and chemical reactions. It involves the study of how electricity can be used to drive chemical reactions or how chemical reactions can produce electricity.

2. How do you measure the potential of a redox reaction?

The potential of a redox reaction can be measured using a device called a voltmeter. The voltmeter measures the potential difference between two electrodes placed in a solution containing the redox reaction. The potential is measured in units of volts (V).

3. What is the difference between anode and cathode?

Anode is the electrode where oxidation occurs, while cathode is the electrode where reduction occurs. In other words, anode is where electrons are lost and cathode is where electrons are gained.

4. Can electrochemistry be used in everyday life?

Yes, electrochemistry has many practical applications in everyday life. It is used in batteries to power electronic devices, in the production of metals such as aluminum and copper, and in the purification of metals through electrolysis. It is also used in electroplating and in fuel cells for alternative energy sources.

5. How does electrochemistry play a role in corrosion?

Electrochemistry is involved in corrosion as it is a type of redox reaction. When a metal is exposed to a corrosive environment, the metal atoms undergo oxidation, losing electrons and forming ions. These ions then react with other substances in the environment, leading to the deterioration of the metal. This process can be prevented by using protective coatings or sacrificial anodes.

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