Help Solving a Puzzling Galvanic Cell Experiment!

[supercali]

iwe had an expirament that goes like this
we made a galvanic cell with half cell zinc and its solution (Zn(NO3)2) and the other half cell was with iron and its solution (Fe(NO3)3) (the Fe solution with ions Fe+3) (both same concentration!) the potential i measured was 0.287V
now i just don't understand how can this be
because the standard potential of Fe+3 + e -> Fe+2 is 0.77V and for Zink it is -0.76V thus we should get in the experiment that the measured potential is 1.53V i just can't understand my result
help please

 

[Borek]

You won't get different answer here than the one I have posted on chemical forums.

 

[Blueshift5]

Based on the information provided, it seems that the measured potential of 0.287V is lower than what is expected based on the standard potentials of the individual half reactions. This could be due to a number of factors, such as experimental error, incorrect concentrations of the solutions, or the presence of impurities in the solutions.

To better understand the results, it would be helpful to review the experimental procedure and make sure all steps were followed correctly. It may also be beneficial to repeat the experiment with different concentrations of the solutions to see if the results are consistent.

Additionally, it is important to consider the overall reaction taking place in the galvanic cell. The measured potential is a result of the combined reactions occurring at the anode (zinc) and cathode (iron). It is possible that the overall reaction is not simply the reduction of Fe+3 to Fe+2, but also involves the oxidation of zinc to zinc ions. This could affect the overall potential measured.

Another factor to consider is the presence of a salt bridge or other means of ion transfer between the two half cells. If this is not present, it could lead to a buildup of charge and affect the measured potential.

In summary, there could be several reasons for the unexpected measured potential in this experiment. Further investigation and careful review of the experimental procedure and conditions may help to clarify the results.