The Effect of Temperature and Concentration on Galvanic Cells

Galvanic cells, such as the Daniell cell below, feature a lot in Chemistry books. For one of my Chemistry EEIs I decided to look at the effect of the temperature and concentration of the solutions on the voltage produced.

I used a simple Daniell cell, which required: zinc sulphate, copper sulphate (both readily available from Bunnings, around $12 to $13 for 500g), a zinc and a copper electrode (zinc plated nail would do), some sodium sulphate (which I created by reacting copper sulphate with sodium bicarbonate) and a voltmeter. I also used an electric frying pan to heat up the beakers containing the solutions.

1-copper-and-zinc-cell

ABSTRACT

Standard electrode potentials are always specified as the voltage potential under standard conditions (25°C, 1.00 mol L-1), as the voltage is dependent upon both temperature and electrolyte concentration. Here, the effect of temperature and concentration on the voltage of a Daniell cell is quantified. The results were quite dissimilar to that of previous work in this area; this may be due to differences in the salt bridge used. At a constant temperature of 30°C, the electrolyte concentration had a moderate effect on voltage potential – up to 1.3%. The relationship between voltage and temperature was dependent upon the electrolyte concentrations, however all trials showed a strong positive correlation. The maximum change in voltage potential observed was 1.95%, when the temperature of the cell changed from 24 to 69°C. These results may be of importance to manufacturers of batteries or electronic devices that might be used in extreme temperatures.

The graph below shows the basic result.

relationship-between-temperature-and-voltage

The full (12 page) report is available here. This was a fantastic investigation, and many questions remain, such as why the results did not follow the predictions from the Nernst equation.

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