Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: 777888 on October 21, 2004, 03:34:18 PM

Title: Predicting REDOX reactions
Post by: 777888 on October 21, 2004, 03:34:18 PM

Question: A piece of copper is added to KMnO4 (acidic solution), predict the redox reaction.

How can I know which one is oxidizing agent and which one is reducing agent? (Becuase I have to find out that and choose the strongest oxidizing and reducing agent!)

Please help me!

Title: Re:Predicting REDOX reactions
Post by: Tetrahedrite on October 21, 2004, 07:34:53 PM

To find which species will be reduced or oxidised you must look at the standard electrode potentials:

MnO4- + 8H+ + 5e-  -->  Mn2+ + 4H2O    E= 1.51V

Cu2+ + 2e-  -->  Cu                               E=0.34V

As you can see MnO4- has a much larger reduction potential and will therefore be reduced
The Cu will obviously be oxidised to Cu2+

Combining the above equations so as to eliminate the electrons we get:

5Cu + 2MnO4- + 16H+  -->  5Cu2+ + 2Mn2+ + 8H2O   E= 1.17V