In a table of standard reduction potentials, the metals with lower free energies are located where?

• A. at the top
• B. at the bottom
• C. in the middle
• D. on the left

Answer: (A)

Think about how stability and the tendency to gain electrons connect. The standard reduction potential E° tells you how readily a species is reduced. The Gibbs free energy change for the reduction is ΔG° = -nFE°. If the reduced form of a metal (the solid metal) is very stable, its energy is low, and the reduction process is highly favorable, which makes E° large and positive. That means metals with lower free energy in the reduced state have the strongest tendency to be reduced, so they appear toward the top of the standard reduction potential table where the potentials are the most positive. Conversely, less stable reduced states show smaller or negative E° and sit lower down. So metals with lower free energies are located at the top.