ELC_Cell Potentials and Thermodynamics Lesson

Cell Potentials and Thermodynamics

In the previous lesson, we learned how to determine if a redox reaction is spontaneous. This can be joined with our knowledge of Gibbs free energy to give us the equation shown below.

CELL POTENTIAL and GIBBS FREE ENERGY ΔG°= -n FE°cell F=96,000 C 1/mol e Δ - This unit will be J. -n - moles of electrons F - the Faraday constant C - Coulomb

Example Calculate AG° for the following reaction with a cell potential of 1.96 V. Mg(s) + Fe²+(aq) → Mg2+(aq) + Fe(s) Use the equation below: AG°-n. Because Fe is oxidized from a +2 oxidation state, 2 moles of electrons are transferred, n = 2. For some reactions, it will be necessary to write the half- reactions to determine n. ΔG°=-(2 mol e-) x (9.65 x 104 c /1 mole -) x (1.96 l / c) ΔG° -3.78 x 105 J-3.78 x 102 kJ = C

Remember to work on the module practice problems as you complete each section of content.

[CC BY-NC-SA 4.0 Links to an external site.] UNLESS OTHERWISE NOTED | IMAGES: LICENSED AND USED ACCORDING TO TERMS OF SUBSCRIPTION - INTENDED ONLY FOR USE WITHIN LESSON.