CHE 141 1st Edition Lecture 34Outline- The Relationship Between Ecell and K- The Effect of Concentration on Ecell- Batteries: Using Chemistry to Generate Electricity- Relationship Between Current, Charge, Time- Using the Faraday ConstantThe Relationship Between Ecell and K- The relationship between standard delta G and K is given by: standard delta G=RTlnK- The relationship between standard delta G and Ecell is standard delta G=-nFEcell:Ecell=RT/nF ln KThe Effect of Concentration on Ecell- We can derive a relationship between Ecell and Ecell by considering the relationship between standard delta G and delta G: delta G=standard delta G=RTlnQ- Ecell=standard Ecell-RT/nF lnQ :this is called the Nerst equation where Ecell=cell potential, Ecell=standard cell potential, n=number of moles of electrons transferred in redox reaction, and Q=reaction quotient- Determine the cell potential for an electrochemical cell based on two half reactions givenThese 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.- Use the standard reduction potentials to balance overall redox equation, calculate standard Ecell then calculate Ecell from standard Ecell- Ecell decreases as reactants are converted into products- Change in potential is small unit cell nearly completely discharged because relation between Q and Ecell is logarithmic- When Ecell=0, the cell reaction has achieved chemical equilibrium- At equilibrium the cell is completely discharged and can no longer pump electrons, its deadBatteries: Using Chemistry to Generate Electricity- Battery-a portable, self-contained electrochemical power source that consists of one or more voltaic cells- Cell potential/rating/rated voltage is the voltage delivered by the battery- If cells are connected in series, the operating potential of the battery is the sum of all the cell potentials of the constituent voltaic/galvanic cellsRelationship Between Current, Charge, Time- Current (A)=charge (C)/time (s)Using the Faraday Constant- Charge is related to the number of electrons being transferred in an electrochemical reaction by the Faraday constant: C=nF- Faradays constant represents the charge on one mole of electrons- Charge on a single electron: 1.602x10^-19- F=9.65x10^4- Can use moles calculations to relate the mass of reactants in an electrochemical equation to electrical
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