emf formula in electrochemistry

Since we want to be the left-hand electrode, this must be reversed and the sign of E° must be changed: \[\ce{Hg(l)} \mid \ce{Hg^{2+} (1 M)} \parallel \ce{H^{+}(1 M)} \mid {H_{2}(1 atm), Pt E^{o} = – 0.85 V}\label{10}\], For the other electrode Table $\PageIndex{1}$ gives, \[\ce{Pt, H_{2}(1 atm)} \mid \ce{H^{+}(1 M)} \parallel \ce{Br^{–}(1 M)} \mid \ce{Br_{2}(l), Pt E^{o} = +1.07 V}\label{11}\], Adding the cells of Eqs. Construct the reference hydrogen electrode and explain why it is a reference. Calculate the standard potential from the reduction potentials. = the number of electrons to be transferred. The difference in potentials of the two half – cells of a cell arises due to the flow of electrons from anode to cathode and flow of current from cathode to anode. Why is the voltage produced by a voltaic cell affected by temperature as described by the Nernst Equation? Is it really safe to use signal or telegram on untrusted phone hardware? The is called the standard cell potential. Chung (Peter) Chieh (Professor Emeritus, Chemistry @ University of Waterloo). Electrons move from the side getting oxidized to the side getting reduced, and you can measure a difference in electric potential. MCAT General Chemistry Review Chapter 12: Electrochemistry. Therefore the emf must be negative and E = – 0.59 V. Example $\PageIndex{2}$ : Voltmeter Readings, If the voltmeter in Figure 17.5 reads 1.10 V, what is the emf for the cell, \[\ce{Cu} \mid \ce{Cu^{2+}(1 M)} \parallel \ce{Zn^{2+}(1 M)} \mid \ce{Zn}\], In this case the shorthand notation corresponds to the reverse of Eq. $$\ce{Pb(s)}, \ce{PbSO_4}|\ce{SO_4^{2-}}(\pu{0.100M})||\ce{Pb^{2+}}(\pu{0.004M})|\ce{Pb(s)}$$ $\ref{5}$ above, the E° is + 0.34 V. For the Zn2+│Zn redox couple, we find E° = – 0.76 V in Table 17.1. The emf of this cell is found to be 0.42 volt. Swapping out our Syntax Highlighter, Hot Meta Posts: Allow for removal by moderators, and thoughts about future…, Nernst equation for a fuel cell when gases are stored separately. Notice: JavaScript is required for this content. $$E_{\text{cell}}=E^0_{\text{cell}}-\frac{0.059}{n}\log\frac{[\text{Products}]}{[\text{Reactants}]}$$. Thus when this electrode is written, to the right of Pt, H2(1 atm)│H+(1 M), as in Eq. What does the word "they" in this sentence replace? Does a soft fork result in two different blockchain versions? So formula becomes:- Use RT/F = 0.059 or 0.06 (1) “The difference in potentials of the two half – cells of a cell known as electromotive force (emf) of the cell or cell potential.”. Cell Potential or EMF of the Cell (1) “The difference in potentials of the two half – cells of a cell known as electromotive force (emf) of the cell or cell potential.”. The emf of such a cell is said to be its standard electromotive force and is given the symbol E °. and $E^0_{\ce{Pb^{2+}|Pb}}=\pu{-0.126V}$, I first found the $\ce{Pb^{2+}}$ concentration in the oxidation half cell using the sulphate ion concentration and the solubility product of lead sulpahte ($2.53\times10^{-8}$) and found the concentration to be $(2.53\times10^{-7})$ 17.10: Electromotive Force of Galvanic Cells, [ "article:topic", "standard reduction potential", "electrical potential difference", "volt", "electromotive force", "authorname:chemprime", "showtoc:no", "license:ccbyncsa" ], Ed Vitz, John W. Moore, Justin Shorb, Xavier Prat-Resina, Tim Wendorff, & Adam Hahn, Chemical Education Digital Library (ChemEd DL), the section on Cell Notation and Conventions, $\ce{F_{2}(g) + 2}e^– \ce{/rightarrow 2F^{–} (aq)}$, $\ce{Co^{3+}(aq) + }e^– \ce{/rightarrow Co^{2+}(aq)}$, $\ce{Au^{+}(aq) + }e^– \ce{\rightarrow Au(s)}$, $\ce{H_{2}O_{2}(aq) + 2H_{3}O^{+}(aq) + 2}e^– \ce{\rightarrow 4H_{2}O(l)}$, $\ce{Ce^{4+}(aq) + }e^– \ce{\rightarrow Ce^{3+}(aq)}$, $\ce{Pb^{4+}(aq) + 2}e^– \ce{\rightarrow Pb^{2+}(aq)}$, $\ce{PbO_{2}(s) + SO_{4}^{2−}(aq) + 4H_{3}O^{+}(aq) + 2}e^– \ce{\rightarrow PbSO_{4}(s) + 6H_{2}O(l)}$, $\ce{NiO_{2}(s) + 4H_{3}O^{+}(aq) + 2}e^– \ce{\rightarrow Ni^{2+}(aq) + 6H_{2}O(l)}$, $\ce{2HClO(aq) + 2H_\ce{3}O^\ce{+}(aq) + 2}e^– \ce{\rightarrow Cl_{2}(g) + 4H_{2}O(l)}$, $\ce{Au^{3+}(aq) + 3}e^− \ce{\rightarrow Au(s)}$, $\ce{MnO_4^{−}(aq) + 8H_{3}O^{+}(aq) + 5}e^– \ce{\rightarrow Mn^{2+}(aq) + 12H_{2}O(l)}$, $\ce{BrO_{3}^{−}(aq) + 6H_{3}O^{+}(aq) + 5}e^− \ce{\rightarrow \frac{1}{2} Br_{2}(aq) + 9H_{2}O(l)}$, $\ce{2ClO_{3}^{−}(aq) + 12H_{3}O^{+}(aq) + 10}e^– \ce{\rightarrow Cl_{2}(g) + 18H_{2}O(l)}$, $\ce{Cr_{2}O_{7}^{2−}(aq) + 14H_{3}O^{+}(aq) + 6}e^– \ce{\rightarrow 2Cr^{3+}(aq) + 21H_{2}O(l)}$, $\ce{Cl_{2} (g) + 2}e^− \ce{\rightarrow 2Cl^{−}(aq)}$, $\ce{N_{2}H_{5}^+(aq) + 3H_{3}O^{+}(aq) + 2}e^- \ce{\rightarrow 2NH_{4}^{+}(aq) + 3H_{2}O(l)}$, $\ce{MnO_{2}(s) + 4H_{3}O^+(aq) + 2}e^– \ce{\rightarrow Mn^{2+}(aq) + 6H_{2}O(l)}$, $\ce{O_{2}(g) + 4H_{3}O^{+}(aq) + 4}e^– \ce{\rightarrow 6H_{2}O(l)}$, $\ce{ClO_{4}^{−}(aq) + 2H_{3}O^{+}(aq) + 2}e^– \ce{\rightarrow ClO_{3}^{−}(aq) + 3H_{2}O(l)}$, $\ce{IO_{3}^{−}(aq) + 6H_{3}O^+(aq) + 5}e^– \ce{\rightarrow \frac{1}{2} I_{2}(aq) + 9H_{2}O(l)}$, $\ce{Pt^{2+}(aq) + 2}e^− \ce{\rightarrow Pt(s)}$, $\ce{Br_{2}(l) + 2}e^− \ce{\rightarrow 2Br^{-}(aq)}$, $\ce{AuCl_{4}^{−}(aq) + 3}e^- \ce{\rightarrow Au(s) + 4Cl^{−}(aq)}$, $\ce{NO_{3}^{−}(aq) + 4H_{3}O^{+}(aq) + 3}e^{–} \ce{\rightarrow NO(g) + 6H_{2}O(l)}$, $\ce{NO_{3}^{−}(aq) + 3H_{3}O^+(aq) + 2}e^– \ce{\rightarrow HNO_{2}(aq) + 4H_{2}O(l)}$, $\ce{Pd^{2+}(aq) + 2}e^− \ce{\rightarrow Pd(s)}$, $\ce{2Hg^{2+}(aq) +2}e^− \ce{\rightarrow Hg_{2}^{2+}(aq)}$, $\ce{Hg^{2+}(aq) +2}e^− \ce{\rightarrow Hg(l)}$, $\ce{SbCl_{6}^{−}(aq) + 2}e^− \ce{\rightarrow SbCl_{4}^{−}(aq) + 2Cl^{−}(aq)}$, $\ce{Ag^{+}(aq) + }e^− \ce{\rightarrow Ag(s)}$, $\ce{Hg_{2}^{2+}(aq) + 2}e^- \ce{\rightarrow 2Hg(l)}$, $\ce{Fe^{3+}(aq) + }e^− \ce{\rightarrow Fe^{2+}(aq)}$, $\ce{[PtCl_{4}]^{2−}(aq) + 2}e^- \ce{\rightarrow Pt(s) + 4Cl^{–}(aq)}$, $\ce{[PtCl_{6}]^{2−}(aq) + 2}e^− \ce{\rightarrow [PtCl_4]^{2−}(aq) + 2Cl^{–}(aq)}$, $\ce{O_{2}(g) + 2H_{3}O^{+}(aq) + 2}e^– \ce{\rightarrow H_{2}O_{2}(aq) + 2H_{2}O(l)}$, $\ce{TeO_{2}(s) + 4H_{3}O^+(aq) + 4}e^– \ce{\rightarrow Te(s) + 6H_{2}O(l)}$, $\ce{H_{3}AsO_{4}(aq) + 2H_{3}O^{+}(aq) + 2}e^− \ce{\rightarrow HAsO_{2}(aq) + 4H_{2}O(l)}$, $\ce{I_{2}(s) + 2}e^− \ce{\rightarrow 2I^{−}(aq)}$, $\ce{Cu^{+}(aq) + }e^− \ce{\rightarrow Cu(s)}$, $\ce{[RhCl_{6}]^{3−}(aq) + 3}e^− \ce{\rightarrow Rh(s) + 6Cl^{–}(aq)}$, $\ce{Cu^{2+}(aq) + 2}e^− \ce{\rightarrow Cu(s)}$, $\ce{Hg_{2}Cl_{2}(s) + 2}e^− \ce{\rightarrow 2Hg(l) + 2Cl^{−}(aq)}$, $\ce{AgCl(s) + }e^− \ce{\rightarrow Ag(s) + Cl^{−}(aq)}$, $\ce{Cu^{2+}(aq) + }e^− \ce{\rightarrow Cu^{+}(aq)}$, $\ce{SO_{4}^{2−}(aq) + 4H_{3}O^{+}(aq) + 2}e^– \ce{\rightarrow H_{2}SO_{3}(aq) + 5H_{2}O(l)}$, $\ce{Sn^{4+}(aq) + 2}e^− \ce{\rightarrow Sn^{2+}(aq)}$, $\ce{S(s) + 2H_{3}O^{+}(aq) + 2}e^– \ce{\rightarrow H_{2}S(aq) + 2H_{2}O(l)}$, $\ce{AgBr(s) + }e^− \ce{\rightarrow Ag(s) + Br^{−}(aq)}$, $\ce{2H_{3}O^{+}(aq) + 2}e^– \ce{\rightarrow 2H_{2}(g) + 2H_{2}O(l )}$ (reference electrode), $\ce{N_{2}O(g) + 6H_{3}O^{+}(aq) + 4}e^– \ce{\rightarrow 2NH_{3}OH^{+}(aq) + 5H_{2}O(l)}$, $\ce{HgS(s, black) + 2H_{3}O^{+}(aq) + 2}e^– \ce{\rightarrow Hg(l) + H_{2}S(g) + 2H_{2}O(l)}$, $\ce{Se(s) + 2H_{3}O^{+}(aq) + 2}e^– \ce{\rightarrow H_{2}Se(aq) + 2H_{2}O(l)}$, $\ce{Pb^{2+}(aq) + 2}e^− \ce{\rightarrow Pb(s)}$, $\ce{Sn^{2+}(aq) + 2}e^− \ce{\rightarrow Sn(s)}$, $\ce{AgI(s) + }e^− \ce{\rightarrow Ag(s) + I^{−}(aq)}$, $\ce{[SnF_6]^{2–}(aq) + 4}e^− \ce{\rightarrow Sn(s) + 6F^{−}(aq)}$, $\ce{Ni^{2+}(aq) + 2}e^− \ce{\rightarrow Ni(s)}$, $\ce{Co^{2+}(aq) + 2}e^− \ce{\rightarrow Co(s)}$, $\ce{Tl^{+}(aq) + }e^− \ce{\rightarrow Tl(s)}$, $\ce{PbSO_{4}(s) + 2}e^− \ce{\rightarrow Pb(s) + SO_{4}^{2−}(aq)}$, $\ce{Cd^{2+}(aq) + 2}e^− \ce{\rightarrow Cd(s)}$, $\ce{Cr^{3+}(aq) + }e^− \ce{\rightarrow Cr^{2+}(aq)}$, $\ce{Fe^{2+}(aq) + 2}e^− \ce{\rightarrow Fe(s)}$, $\ce{2CO_{2}(g) + 2H_{3}O^{+}(aq) + 2}e^– \ce{\rightarrow (COOH)_{2}(aq) + 2H_{2}O(l)}$, $\ce{Ga^{3+}(aq) + 3}e^− \ce{\rightarrow Ga(s)}$, $\ce{Cr^{3+}(aq) + 3}e^− \ce{\rightarrow Cr(s)}$, $\ce{Zn^{2+}(aq) + 2}e^− \ce{\rightarrow Zn(s)}$, $\ce{Cr^{2+}(aq) + 2}e^− \ce{\rightarrow Cr(s)}$, $\ce{V^{2+}(aq) + 2}e^− \ce{\rightarrow V(s)}$, $\ce{Mn^{2+}(aq) + 2}e^− \ce{\rightarrow Mn(s)}$, $\ce{Zr^{4+}(aq) + 4}e^− \ce{\rightarrow Zr(s)}$, $\ce{Al^{3+}(aq) + 3}e^− \ce{\rightarrow Al(s)}$, $\ce{H_{2}(g) + 2}e^− \ce{\rightarrow 2H^{−}(aq)}$, $\ce{Mg^{2+}(aq) + 2}e^− \ce{\rightarrow Mg(s)}$, $\ce{Na^{+}(aq) + }e^− \ce{\rightarrow Na(s)}$, $\ce{Ca^{2+}(aq) + 2}e^− \ce{\rightarrow Ca(s)}$, $\ce{Sr^{2+}(aq) + 2}e^− \ce{\rightarrow Sr(s)}$, $\ce{Ba^{2+}(aq) + 2}e^- \ce{\rightarrow Ba(s)}$, $\ce{Rb^{+}(aq) + }e^− \ce{\rightarrow Rb(s)}$, $\ce{K^{+}(aq) + }e^− \ce{\rightarrow K(s)}$, $\ce{Li^{+}(aq) + }e^− \ce{\rightarrow Li(s)}$, $\ce{ClO^{–}(aq) + H_{2}O(l) + 2}e^– \ce{\rightarrow Cl^{–}(aq) + 2OH^{–}(aq)}$, $\ce{OOH^{-}(aq) + H_{2}O(l) + 2}e^– \ce{\rightarrow 3OH^{–}(aq)}$, $\ce{2NH_{2}OH(aq) + 2}e^– \ce{\rightarrow N_{2}H_{4}(aq) + 2OH^{-}(aq)}$, $\ce{ClO_{3}^{–}(aq) + 3H_{2}O(l) + 6}e^– \ce{\rightarrow Cl^{–}(aq) + 6OH^{–}(aq)}$, $\ce{MnO_{4}^{–}(aq) + 2H_{2}O(l) + 3}e^– \ce{\rightarrow MnO_{2}(s) + 4OH^{–}(aq)}$, $\ce{MnO_{4}^{–}(aq) + }e^– \ce{\rightarrow MnO_{4}^{2–}(aq)}$, $\ce{NiO_{2}(s) + 2H_{2}O(l) + 2}e^– \ce{\rightarrow Ni(OH)_{2}(s) + 2OH^{–}(aq)}$, $\ce{Ag_{2}CrO_{4}^{–}(s) + 2}e^– \ce{\rightarrow 2Ag(s) + CrO_{4}^{2–}(aq)}$, $\ce{O_{2}(g) + 2H_{2}O(l) + 4}e^– \ce{\rightarrow 4OH^{–}(aq)}$, $\ce{ClO_{4}^{–}(aq) + H_{2}O(l) + 2}e^– \ce{\rightarrow ClO_{3}^{–}(aq) + 2OH^{–}(aq)}$, $\ce{Ag_{2}O(s) + H_{2}O(l) + 2}e^– \ce{\rightarrow 2Ag(s) + 2OH^{–}(aq)}$, $\ce{2NO_{2}^{–}(aq) + 3H_{2}O(l) + 4}e^– \ce{\rightarrow N_{2}O(g) + 6OH^{–}(aq)}$, $\ce{[Co(NH_{3})_{6}]^{3+}(aq) + }e^- \ce{\rightarrow [Co(NH_{3})_{6}]^{3+}(aq)}$, $\ce{HgO(s) + H_{2}O(l) + 2}e^– \ce{\rightarrow Hg(l) + 2OH^{–}(aq)}$, $\ce{O_{2}(g) + H_{2}O(l) + 2}e^– \ce{\rightarrow OOH^{–}(aq) + OH^{–}(aq)}$, $\ce{NO_{3}^{-}(aq) + H_{2}O(l) + 2}e^– \ce{\rightarrow NO_{2}^{–}(aq) + 2OH^{–}(aq)}$, $\ce{MnO_{2}(s) + 2H_{2}O(l) + 2}e^– \ce{\rightarrow Mn(OH)_{2}(s) + 2OH^{–}(aq)}$, $\ce{CrO_{4}^{2–}(aq) + 4H_{2}O(l) + 3}e^– \ce{\rightarrow Cr(OH)_{3}(s) + 5OH^{–}(aq)}$, $\ce{Cu_{2}O(s) + H_{2}O(l) + 2}e^– \ce{\rightarrow 2Cu(s) + 2OH^{–}(aq)}$, $\ce{FeO_{2}(aq) + H_{2}O(l) + 2}e^– \ce{\rightarrow HFeO_{2}^{–}(aq) + OH^{–}(aq)}$, $\ce{2H_{2}O(l) + 2}e^– \ce{\rightarrow H_{2}(g) + 2OH^{–}(aq)}$, $\ce{2NO_{3}^{–}(aq) + 2H_{2}O(l) + 2}e^– \ce{\rightarrow N_{2}O_{4}(g) + 4OH^{–}(aq)}$, $\ce{HFeO_{2}^{-}(aq) + 2}e^– \ce{\rightarrow Fe(s) + 3OH^{–}(aq)}$, $\ce{SO_{4}^{2–}(aq) + H_{2}O(l) + 2}e^– \ce{\rightarrow SO_{3}^{2–}(aq) + 2OH^{–}(aq)}$, $\ce{N_{2}(g) + 4H_{2}O(l) + 4}e^– \ce{\rightarrow N_{2}H_{4}(aq) + 4OH^{–}(aq)}$, $\ce{[Zn(OH)_{4}]^{2–}(aq) + 2}e^– \ce{\rightarrow Zn(s) + 4OH^{–}(aq)}$, $\ce{Zn(OH)_{2}(s) + 2}e^{–} \ce{\rightarrow Zn(s) + 2OH^{–}(aq)}$, $\ce{[Zn(CN)_{4}]^{2–}(aq) + 2}e^– \ce{\rightarrow Zn(s) + 4CN^{–}(aq)}$, $\ce{Cr(OH)_{3}(s) + 3}e^– \ce{\rightarrow Cr(s) + 3OH^{–}(aq)}$, $\ce{SiO_{3}^{2–}(aq) + 3H_{2}O(l) + 4}e^– \ce{\rightarrow Si(s) + 6OH^{–}(aq)}$.