Low Voltage Galvanic Cell Troubleshooting

[Tido611]

I had to make a galvanic cell for my chemistry class and it was supposed to have a voltage of 2.3 but for some reason it only was .5. My cell was comprised of a iron and aluminim electrode with the respective nitrates.( potassium nitrate salt bridge) it was wondering if anybody knew why it would have such a low voltage. I sanded the electrodes to expose fresh umoxidesed metal.

 

[mrjeffy321]

What were the concentrations of the Iron and Aluminum Nitrate solutions?

The stamdard reduction potentials of the two metals are measured under standard cell conditions, one of which being a 1 M solution.

Using the nernst equation,
http://chem.ch.huji.ac.il/~eugeniik/nernst_equation.htm
one could find the theoretical cell potential under non standard cell conditions by knowing the standard reduction potentials, temperature, and concentraiton of the two solutions using in the galvanic cel.

 

[Tido611]

they were 1mol concentrations, that page would probably be really helpful if i understood it, the introductary stuf was removed too. Any other sources?

 

[mrjeffy321]

There are plenty of other pages descring the nernst equation, just do a http://www.google.com/search?hl=en&q=nernst+equation".
http://hyperphysics.phy-astr.gsu.edu/Hbase/Chemical/electrode.html

If the concentrations were about 1 Molar, you should have been getting pretty close to the standard cell potentials.
The only other thing I could think of is that perhaps the RedOx reaction which is occurring is not the reaction you are anticipating...something is not getting oxidized/reduced the way you think, perhaps.