E Values and Reaction Tendency

Basically, the E° values of these half-reactions express the tendency for the reduction half-reaction to occur when all reactants and products are present at unit activity the more positive the value of E°, the greater the tendency of the reduction halfreaction to proceed. (In a simplified sense, the activity of a substance is 1 when its 

Half-reactions and their E° values can be used to explain observations such as the following A solution of copper(II) ion flows through a lead pipe, and the lead acquires a layer of copper metal through the reaction 

This reaction occurs because the copper(n) ion has a greater tendency to acquire electrons than the lead ion has to retain them. This reaction can be obtained by subtracting the lead half-reaction. Equation 8.10.8, from the copper half-reaction. Equation 8.10.7  

The appropriate mathematical manipulation of the values of the half-reactions enables calculation of an E° for the overall reaction, the positive value of which indicates that Reaction 8.10.10 tends to go to the right as written. This is in fact what occurs when lead metal directly contacts a solution of copper(ll) ion. Therefore, if a 

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