This applet models the effect of concentration on the potential of a galvanic cell.
Clicking on c+ increases the molarity of the anode (by definition, where oxidation takes place), from 0.0001 M to 1.0 M. Click on c- to decrease the molarity of the anode. Clicking on c+ increases the molarity of the cathode (where reduction takes place), from 0.0001 M to 1.0 M. Click on c- to decrease the molarity of the cathode. Note that the molarities refer to the concentrations of the appropriate cations, not the free metals themselves (which, being insoluble in aqueous solution, do not have a concentration).
Clicking on ano+ cycles through the possible anodes, and cat+ cycles through the possible cathodes. Since all the available materials are accessible as either cathodes or anodes (their particular status in a cell depends on the other), it is possible to select such a combination of materials that the anode and cathode are reversed. This will become apparent when the voltage is displayed by the applet. For a proper (by definition) combination of anode and cathode, the voltage will be positive. When the anode and cathode are effectively reversed, the voltage will be negative.
Activities (deviations from ideal behavior, especially prominant in concentrated solutions) are ignored here.
© 2004-2011 by Lawrence T. Sein. All rights reserved.
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