A simple question

[dttom]

I would like to ask would the same electrode dipped into different electrolytes affect its electrode potential, say, would the electrode potential of Zn/Zn2+ differ when Zn electrode if dipped into sodium chloride solution instead of 1M Zn2+ solution?

 

And I would like to know how cathodic protection work. I was just told that during the process, metal article to be protected is connected to the negative terminal of an electrochemical cell making it as the cathode, as electrons flow from the negative terminal to the positive terminal (the metal article be protected), it prevents the article being corroded when exposed to moist air. Afterward, oxygen receives the electrons and react together with water to form hydroxide ion; on the other hand, let the anode in the electrochemical cell as zinc, zinc continuously loses electron to form Zn2+ ion. Howeve, there would be excess positively charged ions accumulated in the cell, while the negative hydroxide ions outside the cell is impossible to get into the cell and neutralize the charge unbalance in the cell, and there would also be a excess negative charge outside, how would this be solve?

[chuinhen]

electrode potential is the potential difference btwn the electrode and its ion.

 

That is when Zn electrode is dip into a solution containing Zn 2+:

 

Zn 2+ + e- <=====> Zn E -0.76

 

The reverse reaction is more readily to take place

 

Hence the electrode dissolve in to the aqueous solution !!!

 

However , this is not a complete cell !!

 

The electron released when Zn dissolve , will remained in the electrode !!!

This will cause the electrode to bcome more negative ..

 

Thus , the negatively charged electrode will attract the Zn 2+ ...

 

this is called the potential difference !!!!!

 

 

 

 

 

 

 

THIS MAY NOT OCCUR IF THE AQUEOUS SOLUTION DOES NOT CONTAIN THE Zn 2+