I did a lab about Voltaic Cells, and the predicted voltages for the cells are different from the predicted...?

Question

I did a lab about Voltaic Cells, and the predicted voltages for the cells are different from the predicted voltages. On the other hand, one of the questions on the lap paper is “suggest reasons for any discrepancy between the predicted voltages for the cells and the observed voltages.”
I have tried to find the reasons, but I can’t find any. Could you please help me?

Answer 1

I take it you mean the observed voltages are different from the predicted ones!

Without knowing the details of your lab, I can't tell which of these reasons may be applicable to you:

- Temperature different from that at which voltage data were given. (In principle, this also applies to pressure, but is less likely to be a significant variance; whereas many voltage tables are given at STP and it is unlikely that the lab was literally at freezing point.)
- Solution concentrations different from those for which voltage data were given.
- Measurement error (unlikely to be a significant source if your only measurement instrument is a digital voltmeter, but may apply in some situations).

Answer 2

Lancenigo di Villorba (TV), Italy

Standing to your question, I should send you an "electrochemical treatise". You gave not us satisfacting informations, thus any physico-chemical parameter could influence your electrochemical experiences.
PLEASE! Can you repeat your question by specific describing of case in work?

I REMEMBER TO YOU THAT, USUALLY, "COMPLEX INTERACTION" ORIGIN MOST OF GAP'S VALUES.

I wait for your new question.

Answer 3

Non faradaic reactions are the reason that volatic cells "run down" when left unused.