he voltage of an electrochemical cell is also related to the Gibbs free energy o
ID: 496971 • Letter: H
Question
he voltage of an electrochemical cell is also related to the Gibbs free energy of its chemical reaction through the relationship of G = -nFE, where n is the number of electrons transferred in the balanced equation, E is the cell's voltage, and F is the Faraday constant (96,485 C/mol).
(a) In order for a reaction to occur (be spontaneous), what must be the sign (+/-) for G?
(b) Under spontaneous circumstances, then, what must be the sign (+/-) for E (your voltage)?
(c) Knowing the answers to (a) and (b) above, how can one deduce the direction of spontaneity for a particular voltaic cell reaction by using only a voltmeter without doing any calculations
Explanation / Answer
For a reaction to occur (be spontaneous), G must be negative (-).
So, E must be negative (+).
(c) Connect the positive terminal of voltmeter to oxidation half cell and negaive terminal of voltmeter to reduction half cell, the voltmeter should show positive voltage then the reaction is spontaneous.