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For example 6L.2 and 6L.2A in the 7th edition textbook, we are asked to write a cell reaction from an electrochemical cell. After writing the reaction, we are asked to determine whether or not the reaction is spontaneous dependent upon a positive cell potential. I don't understand how to answer this part, how do we know if a reaction is spontaneous given a positive cell potential?
I believe that if the reaction potential is positive then the reaction is spontaneous. They are related by deltaG = -nFE where E is the cell potential. If it is positive then delta G must be negative so it's spontaneous.
From thermodynamics, we learned that if deltaG is negative the reaction is spontaneous. When applying this to electrochemistry and looking at the equation deltaG=-nFE, we see that a negative deltaG is acquired when E is positive. This makes sense as it was discussed in lecture that a positive voltage means a favorable (spontaneous) reaction.
a reaction is spontaneous if gibbs free energy is negative
A positive cell potential (E) will result in a negative delta G (via the equation delta G = -nFE), thus creating a spontaneous reaction. Similarly, a negative cell potential will result in a positive delta G, creating a nonspontaneous reaction
a negative delta G signifies the reaction is spontaneous.