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Galvanic Elements Constructor
 
This model illustrates the dependence of a galvanic element's EMF on the material of the electrodes. Choose the various material options by pressing the buttons that determine the makeup of the first and the second electrode. Reduced and oxidized forms of the substances that result from reactions in the galvanic element appear next to each button.
Note that the electrodes with the higher standard potential (i.e., the ones that are more resistant to oxidization) serve as positive poles in the galvanic element, while the other electrodes - those with a lower standard potential - liberate the electrons.
If the electrodes of the galvanic element are composed of the same material and are placed in the electrolyte of the same composition, such a galvanic element has no practical application. In this model, a zero on the voltmeter in the element circuit indicates such a condition. The galvanic element EMF calculations are presented at the bottom left of the model. The EMF is equal to the difference between the standard potentials of the electrodes. Note that the standard potential is the EMF of an element that has one electrode made of tested material and the second electrode is a standard hydrogen electrode.

Consider a standard hydrogen electrode that is immersed into the electrolyte of the galvanic element in question. The galvanic element's EMF is an algebraic sum of the EMF values of the two galvanic elements that are connected in a series. The first element consists of the first electrode of the initial element and a standard electrode, while the second element is composed of the standard electrode and the second electrode of the initial element.

 
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