Unit 9: ElectroChemistry

Unit 9 Learning Targets/Objectives per topic

Topic 9.1: Introduction to Entropy

• I can identify the sign and relative magnitude of the entropy change associated with chemical or physical processes.

• I can explain how entropy increases as matter become more dispersed and particles become more free to move occupying a larger volume.

• I can explain how entropy increases with higher temperatures as particles gain more kinetic energy.

Topic 9.2: Absolute Entropy and Entropy Change

• I can calculate the entropy change for a chemical or physical process based on the absolute entropies of the species involved in the process.

• I can calculate the entropy change for a chemical reaction using the formula ΔS°reaction= Σ∆S°products−Σ∆S°reactants

Topic 9.3: Gibbs Free Energy and Thermodynamic Favorability

• I can explain whether a physical or a chemical process is thermodynamically favored based on an evaluation of ∆G°.

• I can calculate Gibbs free energy of a process or a chemical reaction using the equation: ΔG° reaction = Σ∆Gf°products − Σ∆Gf°reactants

• I can use both entropy and enthalpy to determine whether a chemical reaction is thermodynamically favored (∆G° < 0) or not.

• I can calculate Gibbs free energy knowing the values of ∆H°and ∆S° using the equation: ΔG° = ΔH° − TΔS°

Topic 9.4: Thermodynamic and Kinetic Control

• I can explain in terms of kinetics, why a thermodynamically favored reaction might not occur at a measurable rate.

• I can explain how some reactions despite their negative ΔG will not take place because of high activation energy, unfavorable orientations and/or the need for collisions of high number of particles.

Topic 9.5: Free Energy and Equilibrium

• I can explain whether a process is thermodynamically favored (∆G° < 0) using the relationship between K, ∆G° and T as indicated in the equations below:

K = e-ΔG°/RT

ΔG° =-RT ln K

• I can explain how processes with ΔG° < 0 favor products (i.e., K > 1) and those with ΔG° > 0 favor reactants (i.e., K < 1).

Topic 9.6: Coupled Reactions

• I can explain the relationship between external sources of energy or coupled reactions and their ability to drive thermodynamically unfavorable processes.

• I can explain how a desired product can be formed by coupling a thermodynamically unfavorable reaction that produces that product to a favorable reaction (e.g., the conversion of ATP to ADP in biological systems). In the coupled system, the individual reactions share one or more common intermediates. The sum of the individual reactions produces an overall reaction that achieves the desired outcome and has ΔG° < 0.

Topic 9.7: Galvanic and Electrolytic Cells

• I can explain the relationship between the physical components of an electrochemical cell and the overall operational principles of the cell.

• I can draw and label the components of an electrolytic cell and a galvanic cell.

• I can write down the reactions taking place at both electrodes in an electrochemical cell.

Topic 9.8: Cell Potential and Free Energy

• I can determine whether an electrochemical cell is thermodynamically favored, base on standard potential and the constituent half reactions within the cell.

Topic 9.9: Cell Potential Under Nonstandard Conditions

• I can explain the relationship between deviations from standard cell conditions and changes in the cell potential.

• I can calculate the new cell potential at nonstandard conditions using the following equation E = E°- (RT/nF) lnQ

Topic 9.10: Electrolysis and Faraday's Law

• I can calculate the amount of charge flow based on changes in the amounts of reactants and products in an electrochemical cell.