#### 051409lecture

CSU Sacramento, C 133
Excerpt: ... rent + time how to relate G to electrical potential component definitions for galvanic cells line notation to express redox reactions in cells standard reduction potential derivation of the Nernst Equation application of the Nernst Equation relating K (equilibrium constant) to E [last topic not covered and not on final due to lack of time] Covered today Applications of The Nernst Equation Examples: Determine the voltage for a Ag/AgCl electrode when [Cl] = 0.010 M if E = 0.222 V? The following electrode, Pb(s)|PbF2(s)|F is used to determine [F]. It is paired with a reference electrode that has an E value of 0.197 V (vs. the S.H.E.) with the reference electrode connected to the + end of the voltmeter. If E for the above reduction reaction is 0.350 V, and the measured voltage is 0.268 V, what is [F]? Electrochemistry Applications of The Nernst Equation Application of Nernst Equation is most common in potentiometry In potentiometry Electrochemistry measured volta ...

#### Lecture 15 Membrane Potentials then Mitochondria

Cincinnati, BIOL 301
Excerpt: ... Lecture 15 Membrane potentials Energy considerations Nernst equation Action potentials Transmission in myelinated neurons Synaptic transmission Mitochondria Structure Main Points for Today Differential permeability to ions sets up potential differences across membranes Action Potentials are based on voltage gated channels Each compartment of the mitochondrion carries out specific tasks Membrane Potential Charge Difference Across a Membrane Ion channel permeable to the positive ions Influences on Ion Movement K+ ions move from high concentration to low Cl- ions left behind; charge differential develops At some point, K+ reaches equilibrium tendency to move with gradient countered by negative charge attraction Equilibrium Potential Membrane potential is a function of the relative concentrations of ions and the relative permeability of the membrane to those ions. For a single ion, the tendency for that ion to move across the membrane is a function of ...

#### ln17s08

University of Texas, CH 302
Excerpt: ... u+ + 2e\$ Eo (reduction) = 0.339V Nis Eo (reduction) = -0.236V = -0.575 = net Cathode Ni+ Now use the equation Eo = (-0.236V) - (0.339V) Cathode - anode Note that AS WRITTEN, this reaction is not spontaneous. However we can reverse the reaction and Eo = +0.575 and the reaction is spontaneous. Cu+ + Nis \$ Cus + Ni+ (spontaneous ) COMPLICATION: THE NERNST EQUATION If electrochemistry was simply a matter of calculating Eo values, life would be easy. But it is not. Do you really think that if we put together a nickel and copper cell and measured the potential, it would be 0.575? If you do, you are probably the same sort of person who believes that the pH of a 0.01M HCl solution is 2 (Go measure it, it is not.) In fact, there are a lot of complications to solution chemistry that need to be addressed if we are going to get a reasonable quantitative handle on the actual potential of an electrochemical cell. We need to deal with CONCENTRATION and how it affects E. We will borrow what we learned back i ...

#### Neurons

Winona, COURSE1 1
Excerpt: ... Study Sheet for Cell Biology 308 Instructions: Print out a copy of this sheet. Write your name in the upper right hand corner. Provide HAND WRITTEN answers or drawings to all questions. Do not use a computer to write answers to these questions. Turn in at or before class time on Monday the 18th of February and get 9 points. Draw a cartoon of the structure of a typical motor neuron. Label the dendrites, cell body, axon hillock, axon, Schwann cells and bulb termini. What gives rise to the resting membrane potential? What is the relationship between the Na/K pump and the membrane potential? Write the Nernst Equation . Consider the Nernst Equation . What variables determine the calculated value of the membrane potential? When can you use the Nernst Equation ? What does the Goldman equation do that the Nernst Equation does not do? What is the relationship between ion channels and changes in the membrane potential? What is measured by patch clamping? How does the structure of the Na+ channel differ from the st ...

#### Neurons

Winona, COURSE1 1
Excerpt: ... Name _ Study Sheet for Cell Biology 308 Instructions: Print out a copy of this sheet. Write your name in the upper right hand corner. Provide HAND WRITTEN answers or drawings to all questions. Do not use a computer to write answers to these questions. Turn in at the beginning of class as indicated on the schedule. Draw a cartoon of the structure of a typical motor neuron. Label the dendrites, cell body, axon hillock, axon, Schwann cells and bulb termini. What gives rise to the resting membrane potential? What is the relationship between the Na/K pump and the membrane potential? Write the Nernst Equation . Consider the Nernst Equation . What variables determine the calculated value of the membrane potential? When can you use the Nernst Equation ? What does the Goldman equation do that the Nernst Equation does not do? What is the relationship between ion channels and changes in the membrane potential? What is measured by patch clamping? How does the structure of the Na+ channel differ from ...

#### Neurons

Winona, COURSE1 1
Excerpt: ... Study Sheet for Cell Biology 308 Instructions: Print out a copy of this sheet. Write your name in the upper right hand corner. Provide HAND WRITTEN answers or drawings to all questions. Do not use a computer to write answers to these questions. Turn in at or before class on Wednesday the 25th of February and get 9 points. No credit will be given for late assignments. Draw a cartoon of the structure of a typical motor neuron. Label the dendrites, cell body, axon hillock, axon, Schwann cells and bulb termini. What gives rise to the resting membrane potential? What is the relationship between the Na/K pump and the membrane potential? Write the Nernst Equation . Consider the Nernst Equation . What variables determine the calculated value of the membrane potential? When can you use the Nernst Equation ? What does the Goldman equation do that the Nernst Equation does not do? What is the relationship between ion channels and changes in the membrane potential? What is measured by patch clamping? How does the str ...

#### 24aL22

Caltech, CH 24
Excerpt: ... Biophysical Chemistry Chemistry 24a Winter Term 2008 Instructor: Sunney I. Chan Lecture 22 March 10, 2008 Electrochemical equilibria. Nernst equation . Electrochemical equilibria: moving electrons and ions moving down potential gradient >0 <0 + + <0 >0 Oxidation-reduction reaction: An oxidation-reduction reaction is one in which different atoms or molecules gain or lose electron(s) during a reaction, that is, their oxidation states change. For an ion, it is often straightforward to assign the oxidation state, as it is given by the ionic charge. The higher the oxidation state, the more oxidized the atom is, while the lower the oxidation state, the more reduced it is. Hence, oxidation and reduction can be considered as loss and gain of electrons, respectively. A simple oxidation-reduction (redox) reaction: Zn0 + Cu2+ Zn2+ + Cu0 This reaction could be written as a sum of the following electron transfer reactions: Zn0 Zn2+ + 2 eCu2+ + 2 e- Cu0 Example of a biologically important redox molecule Cytochrom ...

#### me664f6assign4

Excerpt: ... ME664 - Corrosion Processes and Engineering Fall 2006 Professor: Grant C. Baker Assignment #4 Due: October 10, 2006 * SHOW YOUR WORK FOR CREDIT * Each Assignment Weighted Equally Each Problem worth 10 points each * Temperature is 25 oC unless otherwise stated. Assume "Activity" = Concentration unless otherwise specified Note #1: Activity of solids and pure liquids=1. Activity of gases = pressure (atm). Note #2: When calculating -cell potentials from the Nernst Equation , use the Nernst Equation on the 1/2 cell reaction written in Redox form (i.e. as a reduction equation). Note #3: The total pressure is assumed to be 1 atm unless other information is given. Note #4: "deaerated" means without air (i.e. no O2). Note #5: If deaerated, then the total pressure is assumed to be due to the remaining gases. For example, if total pressure is 1 atm and the system is deaerated with only H2 present, then the H2 concentration is 1 atm. Note #6: Some authors (such as Uhlig) report activity coefficients using concentr ...

#### Lecture_20_spring_2007

Rochester, CHEM 132
Excerpt: ... of 298 K and 1 Molar concentrations. We can use the current we generate from a galvanic cell to do electrical work. 2. Our previous relationships involving G will therefore be useful to us, including Hess Law and the dependence of G on pressures (concentrations). Specifically, we expand our use of G = G0 + RTlnQ where Q is the reaction quotient, to derive the dependence of cell potential (battery voltage) E on concentration. The result is the Nernst equation , E = E0 (0.0592/n)log10Q. 3. One implication of the Nernst equation is that we can make working galvanic cells where the half reactions at the anode and cathode involve the same reaction running in opposite directions. These are called concentration cells and rely on entropic rather than energetic driving forces. 4. The Nernst equation also gives us a relationship for the equilibrium constant for a reduction oxidation reaction that tells us how far it will go. In other words, we can determine how much current we can draw before the battery ...

#### Lecture 23 Ch14b

N. Arizona, CHM 320
Excerpt: ... re,then: If Ecell>0, the reaction is spontaneous to the right If Ecell<0, the reaction is spontaneous to the left CHM 320 - Lecture 23 Chapt 14 Relationship between E and the Equilibrium Constant Recall: G (Gibbs free energy) = - n (moles) x F (Faraday constant) x E (volts) K (equilbrium constant) = e- G/RT K = e- (-nFE/RT) At 25 C K = 10nE/0.05916 or E = (0.05916/n) log K CHM 320 - Lecture 23 Chapt 14 Problem - Calculate the E and K for the following reaction: Cr2+ + Fe(s) Fe2+ + Cr(s) CHM 320 - Lecture 23 Chapt 14 Nernst Equation The Nernst equation allows you to determine the cell potential when the activities of the species involved 1 (i.e. non-standard conditions, more typical to real-life) For aA + ne- bB E = E - (RT/nF) ln (Abb / Aaa) At 25 C: E = E - (0.05916/n) log (Abb / Aaa) CHM 320 - Lecture 23 Chapt 14 Nernst Equation Accounts for potentials of cells where the reagents are not at an activity of 1 Remember that standard potentials a ...

#### QuizscheduleSpring.08

Georgetown, MATH 200
Excerpt: ... ubility Equilibria Applications in Equilibria Problem Solving 7 8 6 PIB lab, Lecture 13 (by default lectures 9-12 too) Read 16.1-16.5. Exp 20 and Problems 16.41-49 odd, 16.50 17.37-40 (these are limiting reactant stoichiometry probs). Read 17.1-17.3. Exp 25 and problems 17.41-17.44 Mar 25, 27, 28 Apr 1, 3, 4 Read 17.4. Ksp lab and problems 17.45-17.55 odd 15.35-49 odd, 16.81,83,85 and 17.17-27 odd Apr 8, 10, 11 Electrochemistry Odd sections: voltaic cells, Nernst Equation Even sections: electrolytic cells and electrolysis No Quiz: Tue prep for exam 3, Thur & Fri Exam 3 returned during recitation Electrochemistry Even sections: voltaic cells, Nernst Equation Odd sections: electrolytic cells and electrolysis 9 Exp 16 and problems 20.83, 85, 89, 90, 105 or Exp 17 and problems 20.2537 odd, 49, 55-60. Apr 15, 17, 18 Apr 22, 24, 25 10 Exp 16 and problems 20.83, 85, 89, 90, 105 or Exp 17 and problems 20.2537 odd, 49, 55-60. ...

#### Lecture_review_12

University of Illinois, Urbana Champaign, CHEM 104
Excerpt: ... ond, if we think back to our discussion on thermodynamics, we should recall that G = w max. This allows us to relate thermochemistry to electrochemistry using the following equation: Go = w max = -nFE for a system at standard conditions. Most of the batteries and Galvanic Cells we will be considering will not be at standard conditions, so we need to consider Gibbs Free Energy at non-standard conditions. Recall that: G = Go + RT ln(Q) 1 Chemistry 104 A/D Lecture Reviews Lecture #12 Because G = -nFE cell, we can now substitute as follows: -nFE cell = -nFEocell + RT ln(Q) Rearranging gives the Nernst Equation : o E cell = E cell RT ln (Q ) nF Where Ecell is the non-standard cell potential, Eocell is the standard cell potential, R is the gas constant, T is the temperature in K, n is the number of moles of electrons in the cell, F is Faradays constant, and Q is the reaction quotient. The Nernst Equation is a powerful tool for us as chemists! It allows us to look at the potential of cell ...

#### Lecture_review_11

University of Illinois, Urbana Champaign, CHEM 104
Excerpt: ... ond, if we think back to our discussion on thermodynamics, we should recall that G = w max. This allows us to relate thermochemistry to electrochemistry using the following equation: Go = w max = -nFE for a system at standard conditions. Most of the batteries and Galvanic Cells we will be considering will not be at standard conditions, so we need to consider Gibbs Free Energy at non-standard conditions. Recall that: G = Go + RT ln(Q) 1 Chemistry 104 B/D Lecture Reviews Lecture #11 Because G = -nFE cell, we can now substitute as follows: -nFE cell = -nFEocell + RT ln(Q) Rearranging gives the Nernst Equation : o E cell = E cell RT ln (Q ) nF Where Ecell is the non-standard cell potential, Eocell is the standard cell potential, R is the gas constant, T is the temperature in K, n is the number of moles of electrons in the cell, F is Faradays constant, and Q is the reaction quotient. The Nernst Equation is a powerful tool for us as chemists! It allows us to look at the potential of cell ...

#### 116AandCExamIVstudyguide

Purdue, CHEM 116
Excerpt: ... CHM 116-C and 116-A Study Guide for Exam IV I. Reading Assignments & Learning Objectives 1. Review the reading assignments & learning objectives for Chapters 3, 15, 16, 17, 18, 19, 6, 20, 22 & 21. You could also review the study guide posted for Exam III. II. Electrochemistry. (Chapter 21). Some additional study guidance for new material. You should be able to do the following: 1. 2. 3. 4. 5. 6. 7. 8. 10. 11. 12. Describe how a galvanic cell operates and the functions of its parts (anode, cathode, electrode, salt bridge). Know how to describe an electrochemical cell in terms of cell (line) notation. Use a table of reduction potentials to find Eo of a voltaic cell. Know the relationships between G, Ecell, K, and equilibrium. Describe how to use an electrolytic cell to electroplate. Relate moles. grams. current, and time in an electrolytic cell. Know how to use the Nernst equation , and how to derive the relationship at equilibrium. Describe how G and E can be used to predict the spontaneity of a reaction. ...

#### lecture_09_26

UC Davis, NPB 100
Excerpt: ... Resting Membrane Potential Lectures What you will learn in these lectures 1. You will learn that all cells, including neurons, have a resting membrane potential. 2. You will learn that two conditions are necessary to produce a voltage across a cell membrane (CM). 1) There must be a concentration difference for at least one species of ion across the CM. 2) The membrane must also be permeable to at least one species of ion. 3.You will learn that two forces will act on ions. 1) A chemical diffusion force and 2) an electrical force. 4.You will learn that a charge difference (voltage) is created across the CM as a result of the chemical and electrical forces. 5.You will learn how to quantify the magnitude of the chemical and electrical forces acting on ions. 6.You will learn that the Nernst equation can be used to predict the potential across the CM for a particular species of ion. 7.You will learn that the Nernst equation is insufficient to predict the voltage across a membrane permeable to multiple ions. 8.You w ...

#### CV

UNC Wilmington, C 445
Excerpt: ... CuSO4(aCu2+=0.010)Cu Anode information is on left, single vertical line represents a phase boundary where potentials may develop, double vertical lines represent two adjacent phase boundaries (usually ends of a salt bridge), activity or concentration of species are included in parentheses. How do you calculate Ecell for a reaction at other than standard conditions? Use the Nernst equation . For a general redox reduction reaction aA + bB the Nernst equation is used : E = Eo' RT ln Q = Eo' 2.303RT log Q = Eo' 0.0591 V log [C]c[D]d (at 25oC) nF nF n [A]a[B]b The Nernst equation is often written with the minus sign changed to plus and the reaction quotient (Q) inverted. cC + dD 2 E = E ' + RT ln 1 = E ' + 2.303RT log 1 = E ' + 0.0591 V log [A] [B] (at 25 C) nF Q nF Q n [C]c[D]d Electrochemistry is usually non spontaneous (force e- transfer to or from a species at an electrode surface). Remember: oxidation = e removal from analyte, reduction = e addition to analyte o o o a b o For t ...

#### Lect3

Toledo, BIO 310
Excerpt: ... Announcements: Last lecture 1. Organization of the nervous system 2. Introduction to the neuron Today electrical potential 1. 2. 3. 4. Generating membrane potential Nernst equation Goldman equation Maintaining ionic distributions Neural Signaling A Simple Circuit Within neurons Between neurons electrical chemical & electrical Bioelectric Potentials Neurons have an electrical potential (voltage) across the cell membrane The inside of the cell is more negative than the outside called the Resting Membrane Potential Measuring Membrane Potential amplifier microelectrode Reference electrode 0 mV Resting potential cell -80 mV Bathing solution time Electrophysiology techniques Silver / Silver chloride wire electrode Amplifier output Reference electrode 3M KCl solution Glass micropipette Very tiny hole (<0.1m) Resting Membrane Potential How is it generated? 1. differential distribution of ions inside and outside the cell 1. Selective Permeability of the membrane to some ions ...

#### ln17pluss09

University of Texas, CH 302
Excerpt: ... + + Nis Break it down into the half cell reactions: Anode Cus + 2eCu+ + 2e Eo (reduction) = 0.339V Nis Eo (reduction) = -0.236V Cathode Ni+ Now use the equation Eo = (-0.236V) - (0.339V) Cathode - anode = -0.575 = net Note that AS WRITTEN, this reaction is not spontaneous. However we can reverse the reaction and Eo = +0.575 and the reaction is spontaneous. Cu+ + Nis Cus + Ni+ (spontaneous ) COMPLICATION: THE NERNST EQUATION If electrochemistry was simply a matter of calculating Eo values, life would be easy. But it is not. Do you really think that if we put together a nickel and copper cell and measured the potential, it would be 0.575? If you do, you are probably the same sort of person who believes that the pH of a 0.01M HCl solution is 2 (Go measure it, it is not.) In fact, there are a lot of complications to solution chemistry that need to be addressed if we are going to get a reasonable quantitative handle on the actual potential of an electrochemical cell. We need to deal with CONC ...

#### ln18s09

University of Texas, CH 302
Excerpt: ... + Cu+ + Nis Break it down into the half cell reactions: Anode Cus + 2eCu+ + 2e Eo (reduction) = 0.339V Nis Eo (reduction) = -0.236V Cathode Ni+ Now use the equation Eo = (-0.236V) - (0.339V) Cathode - anode = -0.575 = net Note that AS WRITTEN, this reaction is not spontaneous. However we can reverse the reaction and Eo = +0.575 and the reaction is spontaneous. Cu+ + Nis Cus + Ni+ (spontaneous ) COMPLICATION: THE NERNST EQUATION If electrochemistry was simply a matter of calculating Eo values, life would be easy. But it is not. Do you really think that if we put together a nickel and copper cell and measured the potential, it would be 0.575? If you do, you are probably the same sort of person who believes that the pH of a 0.01M HCl solution is 2 (Go measure it, it is not.) In fact, there are a lot of complications to solution chemistry that need to be addressed if we are going to get a reasonable quantitative handle on the actual potential of an electrochemical cell. We need to deal ...

#### Lipids_Membranes_h

N.C. State, CH 433
Excerpt: ... Potential The membrane potential is transmembrane electrical potential difference expressed inside with respect to outside. Using the outside as the reference potential makes sense as all cells share that outside. This choice of direction (or sign convention) affects other measures of electrical properties, notably transmembrane current, which are all expressed inside with respect to outside. Thus our current convention is that current crossing the membrane from inside to outside is positive. In physics we express the potential as V (unit is the volt). In chemistry the Nernst equation is used to describe the dependence of the oxidation potential on concentration. The symbol is E (or Eo) and the unit is also the volt. 4 The Nernst equation The Nernst equation describes the potential for each half-reaction a(Ox) + neThe electrode potential is given by: [Red] E = E o RT ln nF [Ox] a b Application of the Nernst equation to membrane potential The free energy per mole of solute moved across the membrane ...

#### Lecture_23

N.C. State, CH 331
Excerpt: ... sign convention) affects other measures of electrical properties, notably transmembrane current, which are all expressed inside with respect to outside. Thus our current convention is that current crossing the membrane from inside to outside is positive. In physics we express the potential as V (unit is the volt). In chemistry the Nernst equation is used to describe the dependence of the oxidation potential on concentration. The symbol is E (or Eo) and the unit is also the volt. The Nernst equation The Nernst equation describes the potential for each half-reaction a(Ox) + neThe electrode potential is given by: b RT ln [Red] E=E a nF [Ox] o b(Red) The standard potential (i.e. potential at 1 molar concentration) is Eo. where R is the gas constant and F is the Faraday (96,450 J/volt). In an electrochemical cell where two half-reactions are combined to make a redox reaction, the electromotive force is: emf = E(+) - E(-) The free energy is G = -nFE. Therefore, the standard free energy change for a redox pro ...

#### Lipids_Membranes

N.C. State, CH 433
Excerpt: ... monoclonal antibodies that recognize a particular cell-surface antigen. ll f ti Transmembrane Potential The membrane potential is transmembrane electrical potential p p g difference expressed inside with respect to outside. Using the outside as the reference potential makes sense as all cells share that outside. This choice of direction (or sign convention) affects other measures of electrical properties, notably transmembrane current, which are all expressed inside with respect to outside. Thus our current convention is that current crossing the membrane from inside to outside is positive. In physics we express the potential as V (unit is the volt). In chemistry the Nernst equation is used to describe the dependence of the oxidation potential on concentration. The symbol is E (or Eo) and the unit is also the volt. The Nernst equation The Nernst equation describes the potential for each half-reaction ( ) a(Ox) + neThe electrode potential is given by: b RT ln [Red] E=E nF [Ox] a o b(Red) ( ) The standa ...

#### Lecture_23

N.C. State, CH 331
Excerpt: ... Using the outside as the reference potential makes sense as all cells share that outside. This choice of direction (or sign convention) affects other measures of electrical properties, notably transmembrane current, which are all expressed inside with respect to outside. Thus our current convention is that current crossing the membrane from inside to outside is positive. In physics we express the potential as V (unit is the volt). In chemistry the Nernst equation is used to describe the dependence of the oxidation potential on concentration. The symbol is E (or Eo) and the unit is also the volt. 4 The Nernst equation The Nernst equation describes the potential for each half-reaction a(Ox) + neThe electrode potential is given by: [Red] b o E = E RT ln a nF [Ox] Application of the Nernst equation to membrane potential The free energy per mole of solute moved across the membrane Gconc = -RTln(Co/Ci) where Co is the concentration outside the membrane and Ci is the concentration inside the membrane. The ...

#### Lecture 2 The Neuron

SUNY Buffalo, PGY 300
Excerpt: ... Lecture 2 The Neuron Chapters Five and Eight THE NEURON: Dendrites Soma Axon Synapse Figure 8-2 Figure 8-3 - Overview Glial Cells Figure 8-5 Overview (1 of 3) Figure 8-6, bc Electrical Terms Charge ions (Na+, K+, Ca+, Cl-) Current ions/sec (into or out of cell) Voltage (Potential) energy to move charge Conductance (1/Resistance) ease of moving charge across membrane ions mV ions Voltage of a Neuron Resting Voltage Potential of a Neuron Na+ Resting Voltage Cl- K+ Figure 5-37 Figure 5-33 Ion Concentrations Out of Equilibrium Figure 5-16 Figure 5-32 - Overview Figure 5-34 - Overview Figure 5-35 Equilibrium Potentials for Key Ions For a Neuron Resting at -60 mV Na+ Cl- K+ +60 mV -63 mV -90 mV Table 8-2 Nernst Equation Electrochemical Equilibrium Voltage = (RT/nF) log (Cout/Cin) R = gas constant T = temperature F = Faraday Constant N = valence Cout = concentrati ...