CH 102 1st Edition Lecture 21Outline of Current Lecture I. ThermodynamicsII. ElectrochemistryIII. Electrochemical ProcessIV. The Fuel CellV. A Battery Consist of Two Half-CellsVI. What if we replace the Zn half cell with a Cd half cell?Current LectureI. Thermodynamicsa. Determines whether a process is spontaneousb. Depends on the value of ΔG, the change in Gibbs free energyi. If ΔG is negative the process is spontaneous and proceeds as writtenii. If ΔG is zero, then the system is at equilibriumiii. If ΔG is positive the process is non-spontaneous and proceeds in the opposite direction1. Δ G = Δ H - T Δ Sc. Introduce a new term, entropy (S), which is a measure of the disorder in a systemi. Negative values of Δ H and positive values of Δ S give a process that is spontaneous in the forward directionii. Positive values of Δ H and negative values of Δ S give a process that is not spontaneous in the forward direction, but is spontaneous in the reverse directionII. Electrochemistrya. Batteries and fuels cellsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. The change in Gibbs free energy for a spontaneous chemical process give electrical energyb. Electrolysisi. Using electrical energy to drive a non-spontaneous process to generate useful chemicalsc. Thermodynamics – G drive the process and the potential (volts) derived from thecell depends on Gd. Kinetics – the rate of the electrochemical reaction determines the current (amps), which is a measure of the number of electrons per seconde. Electrical power – volts x ampsf.III. Electrochemical Processa. Electrons are lost by one chemical species and gained by another chemical speciesi. e.g., the hydrogen-oxygen fuel cellb. At one electrodei. H2 (g) → 2 H+ (aq) + 2 e-c. At the other electrodei. O2 + 4 H+ + 4 e- → 2 H2Od. Reductioni. A chemical species receives electron, that species is reducede. Oxidationi. A chemical species loses electrons, that species is oxidizedIV. The Fuel Cella. The fuel cell uses a spontaneous chemical process to generate electrical energyb. But how much energy?c. The electrochemical potential (E)d. Each half cell has a standard potential (E°) measure under standard conditionsi. Temperature is 25 C, or 298 Kii. Concentration of all species dissolved in solution is 1 Miii. Or the partial pressure of a gas is 1 atme. Reference electrodei. 2 H+ (aq) + 2 e- → H2 (g)f. By international convention the reduction potential for the hydrogen process is 0 V, E = 0 Vg. The potential for every other electrochemical process is determined relative to the standard hydrogen electrodeV. A Battery Consist of Two Half-Cellsa. Consider one half-cell containing a copper electrode in a 1 M solution of copper sulfateb. Another half cell contains a zinc electrode in a 1 M solution of zinc nitratec. The two half-cells are connected by a salt bridged. Reduction Potentialsi. copper electrode in a 1 M solution of copper sulfate1. Cu2+ (aq) + 2 e- → Cu (s) E° = +0.34 Vii. zinc electrode in a 1 M solution of zinc nitrate1. Zn2+ (aq) + 2 e- → Zn (s) E° = -0.76 Viii. The half cell with the highest reduction potential is the cathodeiv. The half-cell with the lowest reduction potential is the anodeVI. What if we replace the Zn half cell with a Cd half cell?a. Reduction Potentialsb. copper electrode in a 1 M solution of copper sulfatei. Cu2+ (aq) + 2 e- → Cu (s) E° = +0.34 Vc. cadmium electrode in a 1 M solution of cadmium nitratei. Cd2+ (aq) + 2 e- → Cd (s) E° = -0.40 Vd. Which is the cathode?e. What is the cell