University of Maryland

• SPAN 112

• Enduring Understanding: ENE-6 Electrical energy can be generated by chemical reactions. Learning Objective: ENE-6.B Explain whether an electrochemical cell is thermodynamically favored, based on its standard cell potential and the constituent half-reactions within the cell. Essential Knowledge: ENE-6.B.1 Electrochemistry encompoasses the study of redox reactions that occur within electrochemical cells. The reactions are either thermodynamically favored (resulting in a positive voltage) or thermodynamically unfavored (resulting in a negative voltage and requiring an externally applied potential for the reaction to proceed). ENE-6.B.2 The standard cell potential of electrochemical cells can be calculated by identifying the oxidation and reduction half-reactions and their respective standard reduction potentials. ENE-6.B.3 ΔG o (standard Gibbs Free Energy change) is proportional to the negative of the cell potential for the redox reaction from which it is constructed. Thus, a cell with a positive Eo involves a thermodynamically favored reaction, and a cell with a negative E o involves a thermodynamically unfavored reaction.