{"id":877,"date":"2021-07-23T09:20:58","date_gmt":"2021-07-23T13:20:58","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/aperrott\/chapter\/galvanic-cells\/"},"modified":"2022-06-23T09:24:44","modified_gmt":"2022-06-23T13:24:44","slug":"galvanic-cells","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/aperrott\/chapter\/galvanic-cells\/","title":{"raw":"17.2 Galvanic Cells","rendered":"17.2 Galvanic Cells"},"content":{"raw":"&nbsp;\r\n<div class=\"textbox textbox--learning-objectives\">\r\n<h3><strong>Learning Objectives<\/strong><\/h3>\r\nBy the end of this section, you will be able to:\r\n<ul>\r\n \t<li>Describe the function of a galvanic cell and its components<\/li>\r\n \t<li>Use cell notation to symbolize the composition and construction of galvanic cells<\/li>\r\n<\/ul>\r\n<\/div>\r\n<p id=\"fs-idm180176640\">As demonstration of spontaneous chemical change, <a class=\"autogenerated-content\" href=\"#CNX_Chem_17_02_CuAg\">(Figure)<\/a> shows the result of immersing a coiled wire of copper into an aqueous solution of silver nitrate. A gradual but visually impressive change spontaneously occurs as the initially colorless solution becomes increasingly blue, and the initially smooth copper wire becomes covered with a porous gray solid.<\/p>\r\n&nbsp;\r\n<div id=\"CNX_Chem_17_02_CuAg\" class=\"scaled-down\">\r\n<div class=\"bc-figcaption figcaption\">A copper wire and an aqueous solution of silver nitrate (left) are brought into contact (center) and a spontaneous transfer of electrons occurs, creating blue Cu<sup>2+<\/sup>(<em data-effect=\"italics\">aq<\/em>) and gray Ag(<em data-effect=\"italics\">s<\/em>) (right).<\/div>\r\n<span id=\"fs-idp67517312\" data-type=\"media\" data-alt=\"This figure includes three photographs. In the first, a test tube containing a clear, colorless liquid is shown with a loosely coiled copper wire outside the test tube to its right. In the second, the wire has been submerged in the clear colorless liquid in the test tube and the surface of the wire is darkened. In the third, the liquid in the test tube is bright blue-green, the wire in the solution appears dark near the top, and a gray \u201cfuzzy\u201d material is present at the bottom of the test tube on the lower portion of the copper coil, giving a murky appearance to the liquid near the bottom of the test tube.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_17_02_CuAg.jpg\" alt=\"This figure includes three photographs. In the first, a test tube containing a clear, colorless liquid is shown with a loosely coiled copper wire outside the test tube to its right. In the second, the wire has been submerged in the clear colorless liquid in the test tube and the surface of the wire is darkened. In the third, the liquid in the test tube is bright blue-green, the wire in the solution appears dark near the top, and a gray \u201cfuzzy\u201d material is present at the bottom of the test tube on the lower portion of the copper coil, giving a murky appearance to the liquid near the bottom of the test tube.\" data-media-type=\"image\/jpeg\" \/><\/span>\r\n\r\n<\/div>\r\n<p id=\"fs-idm216506080\">These observations are consistent with (i) the oxidation of elemental copper to yield copper(II) ions, Cu<sup>2+<\/sup><em data-effect=\"italics\">(aq)<\/em>, which impart a blue color to the solution, and (ii) the reduction of silver(I) ions to yield elemental silver, which deposits as a fluffy solid on the copper wire surface. And so, <em data-effect=\"italics\">the direct transfer of electrons from the copper wire to the aqueous silver ions is spontaneous<\/em> under the employed conditions. A summary of this redox system is provided by these equations:<\/p>\r\n\r\n<div id=\"fs-idm479533072\" style=\"padding-left: 40px\" data-type=\"equation\">overall reaction:\u00a0 Cu(<em>s<\/em>) + 2Ag<sup>+<\/sup>(<em>aq<\/em>) \u27f6 Cu<sup>2+<\/sup>(<em>aq<\/em>) + 2Ag(<em>s<\/em>)<\/div>\r\n<div style=\"padding-left: 40px\" data-type=\"equation\">oxidation half-reaction:\u00a0 Cu(<em>s<\/em>) \u27f6 Cu<sup>2+<\/sup>(<em>aq<\/em>) + 2e<sup>\u2212<\/sup><\/div>\r\n<div style=\"padding-left: 40px\" data-type=\"equation\">reduction half-reaction: 2Ag<sup>+<\/sup>(<em>aq<\/em>) + 2e<sup>\u2212<\/sup> \u27f6 2Ag(<em>s<\/em>)<\/div>\r\n<p id=\"fs-idm201862608\">Consider the construction of a device that contains all the reactants and products of a redox system like the one here, but prevents physical contact between the reactants. Direct transfer of electrons is, therefore, prevented; transfer, instead, takes place indirectly through an external circuit that contacts the separated reactants. Devices of this sort are generally referred to as <em data-effect=\"italics\">electrochemical cells<\/em>, and those in which a spontaneous redox reaction takes place are called <strong>galvanic cells<\/strong> (or <strong>voltaic cells<\/strong>).<\/p>\r\n<p id=\"fs-idm196674112\">A galvanic cell based on the spontaneous reaction between copper and silver(I) is depicted in <a class=\"autogenerated-content\" href=\"#CNX_Chem_17_02_Galvanicel\">(Figure)<\/a>. The cell is comprised of two <strong>half-cells<\/strong>, each containing the redox conjugate pair (\u201ccouple\u201d) of a single reactant. The half-cell shown at the left contains the Cu(0)\/Cu(II) couple in the form of a solid copper foil and an aqueous solution of copper nitrate. The right half-cell contains the Ag(I)\/Ag(0) couple as solid silver foil and an aqueous silver nitrate solution. An external circuit is connected to each half-cell at its solid foil, meaning the Cu and Ag foil each function as an <em data-effect=\"italics\">electrode<\/em>. By definition, the <strong>anode <\/strong>of an electrochemical cell is the electrode at which oxidation occurs (in this case, the Cu foil) and the <strong>cathode <\/strong>is the electrode where reduction occurs (the Ag foil). The redox reactions in a galvanic cell occur only at the interface between each half-cell\u2019s reaction mixture and its electrode. To keep the reactants separate while maintaining charge-balance, the two half-cell solutions are connected by a tube filled with inert electrolyte solution called a <strong>salt bridge<\/strong>. The spontaneous reaction in this cell produces Cu<sup>2+<\/sup> cations in the anode half-cell and consumes Ag<sup>+<\/sup> ions in the cathode half-cell, resulting in a compensatory flow of inert ions from the salt bridge that maintains charge balance. Increasing concentrations of Cu<sup>2+<\/sup> in the anode half-cell are balanced by an influx of NO<sub>3<\/sub><sup>\u2212<\/sup> from the salt bridge, while a flow of Na<sup>+<\/sup> into the cathode half-cell compensates for the decreasing Ag<sup>+<\/sup> concentration.<\/p>\r\n&nbsp;\r\n<div id=\"CNX_Chem_17_02_Galvanicel\" class=\"scaled-down\">\r\n<div class=\"bc-figcaption figcaption\">A galvanic cell based on the spontaneous reaction between copper and silver(I) ions.<\/div>\r\n<span id=\"fs-idp20459472\" data-type=\"media\" data-alt=\"This figure contains a diagram of an electrochemical cell. Two beakers are shown. Each is just over half full. The beaker on the left contains a blue solution and is labeled below as \u201c1 M solution of copper (II) nitrate ( C u ( N O subscript 3 ) subscript 2 ).\u201d The beaker on the right contains a colorless solution and is labeled below as \u201c1 M solution of silver nitrate ( A g N O subscript 3 ).\u201d A glass tube in the shape of an inverted U connects the two beakers at the center of the diagram. The tube contents are colorless. The ends of the tubes are beneath the surface of the solutions in the beakers and a small gray plug is present at each end of the tube. The plug in the left beaker is labeled \u201cPorous plug.\u201d At the center of the diagram, the tube is labeled \u201cSalt bridge ( N a N O subscript 3 ). Each beaker shows a metal strip partially submerged in the liquid. The beaker on the left has an orange-brown strip that is labeled \u201cC u anode negative\u201d at the top. The beaker on the right has a silver strip that is labeled \u201cA g cathode positive\u201d at the top. A wire extends from the top of each of these strips to a rectangle indicating \u201cexternal circuit\u201d that is labeled \u201cflow of electrons\u201d with an arrow pointing to the right following. A curved arrow extends from the C u strip into the surrounding solution. The tip of this arrow is labeled \u201cC u superscript 2 plus.\u201d A curved arrow extends from the salt bridge into the beaker on the left into the blue solution. The tip of this arrow is labeled \u201cN O subscript 3 superscript negative.\u201d A curved arrow extends from the solution in the beaker on the right to the A g strip. The base of this arrow is labeled \u201cA g superscript plus.\u201d A curved arrow extends from the colorless solution to salt bridge in the beaker on the right. The base of this arrow is labeled \u201cN O subscript 3 superscript negative.\u201d Just right of the salt bridge in the colorless solution is the label \u201cN a superscript plus.\u201d Just above this region of the tube appears the label \u201cFlow of cations.\u201d Just left of the salt bridge in the blue solution is the label \u201cN O subscript 3 superscript negative.\u201d Just above this region of the tube appears the label \u201cFlow of anions.\u201d\"><img src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_17_02_Galvanicel.jpg\" alt=\"This figure contains a diagram of an electrochemical cell. Two beakers are shown. Each is just over half full. The beaker on the left contains a blue solution and is labeled below as \u201c1 M solution of copper (II) nitrate ( C u ( N O subscript 3 ) subscript 2 ).\u201d The beaker on the right contains a colorless solution and is labeled below as \u201c1 M solution of silver nitrate ( A g N O subscript 3 ).\u201d A glass tube in the shape of an inverted U connects the two beakers at the center of the diagram. The tube contents are colorless. The ends of the tubes are beneath the surface of the solutions in the beakers and a small gray plug is present at each end of the tube. The plug in the left beaker is labeled \u201cPorous plug.\u201d At the center of the diagram, the tube is labeled \u201cSalt bridge ( N a N O subscript 3 ). Each beaker shows a metal strip partially submerged in the liquid. The beaker on the left has an orange-brown strip that is labeled \u201cC u anode negative\u201d at the top. The beaker on the right has a silver strip that is labeled \u201cA g cathode positive\u201d at the top. A wire extends from the top of each of these strips to a rectangle indicating \u201cexternal circuit\u201d that is labeled \u201cflow of electrons\u201d with an arrow pointing to the right following. A curved arrow extends from the C u strip into the surrounding solution. The tip of this arrow is labeled \u201cC u superscript 2 plus.\u201d A curved arrow extends from the salt bridge into the beaker on the left into the blue solution. The tip of this arrow is labeled \u201cN O subscript 3 superscript negative.\u201d A curved arrow extends from the solution in the beaker on the right to the A g strip. The base of this arrow is labeled \u201cA g superscript plus.\u201d A curved arrow extends from the colorless solution to salt bridge in the beaker on the right. The base of this arrow is labeled \u201cN O subscript 3 superscript negative.\u201d Just right of the salt bridge in the colorless solution is the label \u201cN a superscript plus.\u201d Just above this region of the tube appears the label \u201cFlow of cations.\u201d Just left of the salt bridge in the blue solution is the label \u201cN O subscript 3 superscript negative.\u201d Just above this region of the tube appears the label \u201cFlow of anions.\u201d\" data-media-type=\"image\/jpeg\" \/><\/span>\r\n\r\n<\/div>\r\n<div id=\"fs-idm191852240\" class=\"bc-section section\" data-depth=\"1\">\r\n<h3 data-type=\"title\"><strong>Cell Notation<\/strong><\/h3>\r\n<p id=\"fs-idm213246704\">Abbreviated symbolism is commonly used to represent a galvanic cell by providing essential information on its composition and structure. These symbolic representations are called <strong>cell notations<\/strong> or <strong>cell schematics<\/strong>, and they are written following a few guidelines:<\/p>\r\n\r\n<ul id=\"fs-idm66905104\" data-bullet-style=\"bullet\">\r\n \t<li>The relevant components of each half-cell are represented by their chemical formulas or element symbols<\/li>\r\n \t<li>All interfaces between component phases are represented by vertical parallel lines; if two or more components are present in the same phase, their formulas are separated by commas<\/li>\r\n \t<li>By convention, the schematic begins with the anode and proceeds left-to-right identifying phases and interfaces encountered within the cell, ending with the cathode<\/li>\r\n<\/ul>\r\n<p id=\"fs-idm178198704\">A verbal description of the cell as viewed from anode-to-cathode is often a useful first-step in writing its schematic. For example, the galvanic cell shown in <a class=\"autogenerated-content\" href=\"#CNX_Chem_17_02_Galvanicel\">(Figure)<\/a> consists of a solid copper anode immersed in an aqueous solution of copper(II) nitrate that is connected via a salt bridge to an aqueous silver(I) nitrate solution, immersed in which is a solid silver cathode. Converting this statement to symbolism following the above guidelines results in the cell schematic:<\/p>\r\n\r\n<div data-type=\"equation\"><\/div>\r\n<div id=\"fs-idm224675200\" style=\"padding-left: 40px\" data-type=\"equation\">Cu(<em>s<\/em>)\u25021 M Cu(NO<sub>3<\/sub>)<sub>2<\/sub>(<em>aq<\/em>)\u25511 M AgNO<sub>3<\/sub>(<em>aq<\/em>)\u2502Ag(<em>s<\/em>)<\/div>\r\n<p id=\"fs-idm183571200\">Consider a different galvanic cell (see <a class=\"autogenerated-content\" href=\"#CNX_Chem_17_02_Oxidareduc\">(Figure)<\/a>) based on the spontaneous reaction between solid magnesium and aqueous iron(III) ions:<\/p>\r\n\r\n<div id=\"fs-idm198448336\" style=\"padding-left: 40px\" data-type=\"equation\">net cell reaction:\u00a0 Mg(<em>s<\/em>) + 2Fe<sup>3+<\/sup>(<em>aq<\/em>) \u27f6 Mg<sup>2+<\/sup>(<em>aq<\/em>) + 2Fe<sup>2+<\/sup>(<em>aq<\/em>)<\/div>\r\n<div style=\"padding-left: 40px\" data-type=\"equation\">oxidation half-reaction:\u00a0 Mg(<em>s<\/em>) \u27f6 Mg<sup>2+<\/sup>(<em>aq<\/em>) + 2e<sup>\u2212<\/sup><\/div>\r\n<div style=\"padding-left: 40px\" data-type=\"equation\">reduction half-reaction:\u00a0 2Fe<sup>3+<\/sup>(<em>aq<\/em>) + 2e<sup>\u2212<\/sup> \u27f6 2Fe<sup>2+<\/sup>(<em>aq<\/em>)<\/div>\r\n<p id=\"fs-idm215655008\">In this cell, a solid magnesium anode is immersed in an aqueous solution of magnesium chloride that is connected via a salt bridge to an aqueous solution containing a mixture of iron(III) chloride and iron(II) chloride, immersed in which is a platinum cathode. The cell schematic is then written as<\/p>\r\n\r\n<div id=\"fs-idm198262288\" style=\"padding-left: 40px\" data-type=\"equation\">Mg(<em>s<\/em>)\u25020.1 M MgCl<sub>2<\/sub>(<em>aq<\/em>)\u25510.2 M FeCl<sub>3<\/sub>(<em>aq<\/em>), 0.3 M FeCl<sub>2<\/sub>(<em>aq<\/em>)\u2502Pt(<em>s<\/em>)<\/div>\r\n<p id=\"fs-idm214418000\">Notice the cathode half-cell is different from the others considered thus far in that its electrode is comprised of a substance (Pt) that is neither a reactant nor a product of the cell reaction. This is required when neither member of the half-cell\u2019s redox couple can reasonably function as an electrode, which must be electrically conductive and in a phase separate from the half-cell solution. In this case, both members of the redox couple are solute species, and so Pt is used as an<strong> inert electrode<\/strong> that can simply provide or accept electrons to redox species in solution. Electrodes constructed from a member of the redox couple, such as the Mg anode in this cell, are called <strong>active electrodes<\/strong>.<\/p>\r\n&nbsp;\r\n<div id=\"CNX_Chem_17_02_Oxidareduc\" class=\"bc-figure figure\">\r\n<div class=\"bc-figcaption figcaption\">A galvanic cell based on the spontaneous reaction between magnesium and iron(III) ions.<\/div>\r\n<span id=\"fs-idm141095104\" data-type=\"media\" data-alt=\"This figure contains a diagram of an electrochemical cell. Two beakers are shown. Each is just over half full. The beaker on the left contains a colorless solution. The beaker on the right also contains a colorless solution. A glass tube in the shape of an inverted U connects the two beakers at the center of the diagram. The tube contents are colorless. The ends of the tubes are beneath the surface of the solutions in the beakers and a small gray plug is present at each end of the tube. At the center of the diagram, the tube is labeled \u201cSalt bridge.\u201d Each beaker shows a metal coils submerged in the liquid. The beaker on the left has a thin, gray, coiled strip that is labeled \u201cM g anode.\u201d The beaker on the right has a black wire that is oriented horizontally and coiled up in a spring-like appearance that is labeled \u201cP t cathode.\u201d Below the coil is the label \u201cF e superscript 3 plus\u201d with a curved right arrowing pointing from that to the label \u201cF e superscript 2 plus.\u201d A wire extends across the top of the diagram that connects the ends of the M g strip and P t cathode just above the opening of each beaker. At the center of the wire above the two beakers is a rectangle labeled \u201cexternal circuit.\u201d Above the rectangle is the label \u201cflow of electrons\u201d followed by a right pointing arrow. An arrow points down and to the right from the label \u201cN a superscript plus\u201d at the upper right region of the salt bride. An arrow points down and to the left from the label \u201cC l superscript negative\u201d at the upper left region of the salt bride. Below the graylug at the left end of the salt bridge in the surrounding solution in the left beaker is the label \u201cC l superscript negative.\u201d Below the coil on this side is a right arrow and the label \u201cM g superscript 2 plus.\u201d The label \u201c0.1 M M g C l subscript 2\u201d appears beneath the left beaker. The label \u201c0.2 M F e C l subscript 3 and 0.3 M F e C l subscript 2.\u201d appears beneath the right beaker.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_17_02_Oxidareduc.jpg\" alt=\"This figure contains a diagram of an electrochemical cell. Two beakers are shown. Each is just over half full. The beaker on the left contains a colorless solution. The beaker on the right also contains a colorless solution. A glass tube in the shape of an inverted U connects the two beakers at the center of the diagram. The tube contents are colorless. The ends of the tubes are beneath the surface of the solutions in the beakers and a small gray plug is present at each end of the tube. At the center of the diagram, the tube is labeled \u201cSalt bridge.\u201d Each beaker shows a metal coils submerged in the liquid. The beaker on the left has a thin, gray, coiled strip that is labeled \u201cM g anode.\u201d The beaker on the right has a black wire that is oriented horizontally and coiled up in a spring-like appearance that is labeled \u201cP t cathode.\u201d Below the coil is the label \u201cF e superscript 3 plus\u201d with a curved right arrowing pointing from that to the label \u201cF e superscript 2 plus.\u201d A wire extends across the top of the diagram that connects the ends of the M g strip and P t cathode just above the opening of each beaker. At the center of the wire above the two beakers is a rectangle labeled \u201cexternal circuit.\u201d Above the rectangle is the label \u201cflow of electrons\u201d followed by a right pointing arrow. An arrow points down and to the right from the label \u201cN a superscript plus\u201d at the upper right region of the salt bride. An arrow points down and to the left from the label \u201cC l superscript negative\u201d at the upper left region of the salt bride. Below the graylug at the left end of the salt bridge in the surrounding solution in the left beaker is the label \u201cC l superscript negative.\u201d Below the coil on this side is a right arrow and the label \u201cM g superscript 2 plus.\u201d The label \u201c0.1 M M g C l subscript 2\u201d appears beneath the left beaker. The label \u201c0.2 M F e C l subscript 3 and 0.3 M F e C l subscript 2.\u201d appears beneath the right beaker.\" data-media-type=\"image\/jpeg\" \/><\/span>\r\n\r\n<\/div>\r\n<div id=\"fs-idm168909584\" class=\"textbox textbox--examples\" data-type=\"example\">\r\n<p id=\"fs-idm148208960\"><strong>Writing Galvanic Cell Schematics <\/strong><\/p>\r\nA galvanic cell is fabricated by connecting two half-cells with a salt bridge, one in which a chromium wire is immersed in a 1 M CrCl<sub>3<\/sub> solution and another in which a copper wire is immersed in 1 M CuCl<sub>2<\/sub>. Assuming the chromium wire functions as an anode, write the schematic for this cell along with equations for the anode half-reaction, the cathode half-reaction, and the overall cell reaction.\r\n<p id=\"fs-idp124889088\"><strong>Solution:<\/strong><\/p>\r\nSince the chromium wire is stipulated to be the anode, the schematic begins with it and proceeds left-to-right, symbolizing the other cell components until ending with the copper wire cathode:\r\n<div id=\"fs-idm184234832\" style=\"padding-left: 40px\" data-type=\"equation\">Cr(<em>s<\/em>)\u25021 M CrCl<sub>3<\/sub>(<em>aq<\/em>)\u25511 M CuCl<sub>2<\/sub>(<em>aq<\/em>)\u2502Cu(<em>s<\/em>)<\/div>\r\n<div data-type=\"equation\"><\/div>\r\n<p id=\"fs-idm191652416\">The half-reactions for this cell are<\/p>\r\n\r\n<div id=\"fs-idm177989472\" style=\"padding-left: 40px\" data-type=\"equation\">anode (oxidation):\u00a0 Cr(s) \u27f6 Cr<sup>3+<\/sup>(<em>aq<\/em>) + 3e<sup>\u2212<\/sup><\/div>\r\n<div style=\"padding-left: 40px\" data-type=\"equation\">cathode (oxidation):\u00a0 Cu<sup>2+<\/sup>(<em>aq<\/em>) + 2e<sup>\u2212<\/sup> \u27f6 Cu(<em>s<\/em>)<\/div>\r\n<p id=\"fs-idm206725184\">Multiplying to make the number of electrons lost by Cr and gained by Cu<sup>2+<\/sup> equal yields<\/p>\r\n\r\n<div id=\"fs-idm479522256\" data-type=\"equation\">\r\n<div id=\"fs-idm177989472\" style=\"padding-left: 40px\" data-type=\"equation\">anode (oxidation):\u00a0 2Cr(s) \u27f6 2Cr<sup>3+<\/sup>(<em>aq<\/em>) + 6e<sup>\u2212<\/sup><\/div>\r\n<div style=\"padding-left: 40px\" data-type=\"equation\">cathode (oxidation):\u00a0 3Cu<sup>2+<\/sup>(<em>aq<\/em>) + 6e<sup>\u2212<\/sup> \u27f6 3Cu(<em>s<\/em>)<\/div>\r\n<\/div>\r\n<p id=\"fs-idm480712000\">Adding the half-reaction equations and simplifying yields an equation for the cell reaction:<\/p>\r\n\r\n<div id=\"fs-idm183688400\" style=\"padding-left: 40px\" data-type=\"equation\">2Cr(<em>s<\/em>) + 3Cu<sup>2+<\/sup>(<em>aq<\/em>) \u27f6 2Cr<sup>3+<\/sup>(<em>aq<\/em>) + 3Cu(<em>s<\/em>)<\/div>\r\n<div data-type=\"equation\"><\/div>\r\n<div data-type=\"equation\"><\/div>\r\n<p id=\"fs-idm199393680\"><strong>Check Your Learning:<\/strong><\/p>\r\nOmitting solute concentrations and spectator ion identities, write the schematic for a galvanic cell whose net cell reaction is shown below.\r\n<div id=\"fs-idm477306416\" style=\"padding-left: 40px\" data-type=\"equation\">Sn<sup>4+<\/sup>(<em>aq<\/em>) + Zn(<em>s<\/em>) \u27f6 Sn<sup>2+<\/sup>(<em>aq<\/em>) + Zn<sup>2+<\/sup>(<em>aq<\/em>)<\/div>\r\n<div data-type=\"equation\"><\/div>\r\n<div id=\"fs-idp13471872\" data-type=\"note\">\r\n<div data-type=\"title\"><strong>Answer:<\/strong><\/div>\r\n<p id=\"fs-idm479605136\" style=\"padding-left: 40px\">Zn(<em>s<\/em>)\u2502Zn<sup>2+<\/sup>(<em>aq<\/em>)\u2551Sn<sup>4+<\/sup>(<em>aq<\/em>), Sn<sup>2+<\/sup>(<em>aq<\/em>)\u2502Pt(<em>s<\/em>)<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div id=\"fs-idm89705136\" class=\"summary\" data-depth=\"1\">\r\n<h3 data-type=\"title\"><strong>Key Concepts and Summary<\/strong><\/h3>\r\n<p id=\"fs-idm71248464\">Galvanic cells are devices in which a spontaneous redox reaction occurs indirectly, with the oxidant and reductant redox couples contained in separate half-cells. Electrons are transferred from the reductant (in the anode half-cell) to the oxidant (in the cathode half-cell) through an external circuit, and inert solution phase ions are transferred between half-cells, through a salt bridge, to maintain charge neutrality. The construction and composition of a galvanic cell may be succinctly represented using chemical formulas and others symbols in the form of a cell schematic (cell notation).<\/p>\r\n\r\n<\/div>\r\n<div id=\"fs-idm190362800\" class=\"exercises\" data-depth=\"1\">\r\n<div id=\"fs-idm33124048\" data-type=\"exercise\">\r\n<div id=\"fs-idm178777776\" data-type=\"problem\">\r\n<p id=\"fs-idp7124096\"><\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox shaded\" data-type=\"glossary\">\r\n<h3 data-type=\"glossary-title\"><strong>Glossary<\/strong><\/h3>\r\n<dl id=\"fs-idp13398640\">\r\n \t<dt>active electrode<\/dt>\r\n \t<dd id=\"fs-idp54206496\">electrode that participates as a reactant or product in the oxidation-reduction reaction of an electrochemical cell; the mass of an active electrode changes during the oxidation-reduction reaction<\/dd>\r\n<\/dl>\r\n<dl id=\"fs-idp4652784\">\r\n \t<dt>anode<\/dt>\r\n \t<dd id=\"fs-idp20601168\">electrode in an electrochemical cell at which oxidation occurs<\/dd>\r\n<\/dl>\r\n<dl id=\"fs-idm120688224\">\r\n \t<dt>cathode<\/dt>\r\n \t<dd id=\"fs-idm171511936\">electrode in an electrochemical cell at which reduction occurs<\/dd>\r\n<\/dl>\r\n<dl id=\"fs-idm139905600\">\r\n \t<dt>cell notation (schematic)<\/dt>\r\n \t<dd id=\"fs-idm155391072\">symbolic representation of the components and reactions in an electrochemical cell<\/dd>\r\n<\/dl>\r\n<dl id=\"fs-idm153779040\">\r\n \t<dt>cell potential (<em data-effect=\"italics\">E<\/em><sub>cell<\/sub>)<\/dt>\r\n \t<dd id=\"fs-idm191155536\">difference in potential of the cathode and anode half-cells<\/dd>\r\n<\/dl>\r\n<dl id=\"fs-idm159189392\">\r\n \t<dt>galvanic (voltaic) cell<\/dt>\r\n \t<dd id=\"fs-idm148308224\">electrochemical cell in which a spontaneous redox reaction takes place; also called a <em data-effect=\"italics\">voltaic cell<\/em><\/dd>\r\n<\/dl>\r\n<dl id=\"fs-idm19899136\">\r\n \t<dt>inert electrode<\/dt>\r\n \t<dd id=\"fs-idm201925328\">electrode that conducts electrons to and from the reactants in a half-cell but that is not itself oxidized or reduced<\/dd>\r\n<\/dl>\r\n<\/div>","rendered":"<p>&nbsp;<\/p>\n<div class=\"textbox textbox--learning-objectives\">\n<h3><strong>Learning Objectives<\/strong><\/h3>\n<p>By the end of this section, you will be able to:<\/p>\n<ul>\n<li>Describe the function of a galvanic cell and its components<\/li>\n<li>Use cell notation to symbolize the composition and construction of galvanic cells<\/li>\n<\/ul>\n<\/div>\n<p id=\"fs-idm180176640\">As demonstration of spontaneous chemical change, <a class=\"autogenerated-content\" href=\"#CNX_Chem_17_02_CuAg\">(Figure)<\/a> shows the result of immersing a coiled wire of copper into an aqueous solution of silver nitrate. A gradual but visually impressive change spontaneously occurs as the initially colorless solution becomes increasingly blue, and the initially smooth copper wire becomes covered with a porous gray solid.<\/p>\n<p>&nbsp;<\/p>\n<div id=\"CNX_Chem_17_02_CuAg\" class=\"scaled-down\">\n<div class=\"bc-figcaption figcaption\">A copper wire and an aqueous solution of silver nitrate (left) are brought into contact (center) and a spontaneous transfer of electrons occurs, creating blue Cu<sup>2+<\/sup>(<em data-effect=\"italics\">aq<\/em>) and gray Ag(<em data-effect=\"italics\">s<\/em>) (right).<\/div>\n<p><span id=\"fs-idp67517312\" data-type=\"media\" data-alt=\"This figure includes three photographs. In the first, a test tube containing a clear, colorless liquid is shown with a loosely coiled copper wire outside the test tube to its right. In the second, the wire has been submerged in the clear colorless liquid in the test tube and the surface of the wire is darkened. In the third, the liquid in the test tube is bright blue-green, the wire in the solution appears dark near the top, and a gray \u201cfuzzy\u201d material is present at the bottom of the test tube on the lower portion of the copper coil, giving a murky appearance to the liquid near the bottom of the test tube.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_17_02_CuAg.jpg\" alt=\"This figure includes three photographs. In the first, a test tube containing a clear, colorless liquid is shown with a loosely coiled copper wire outside the test tube to its right. In the second, the wire has been submerged in the clear colorless liquid in the test tube and the surface of the wire is darkened. In the third, the liquid in the test tube is bright blue-green, the wire in the solution appears dark near the top, and a gray \u201cfuzzy\u201d material is present at the bottom of the test tube on the lower portion of the copper coil, giving a murky appearance to the liquid near the bottom of the test tube.\" data-media-type=\"image\/jpeg\" \/><\/span><\/p>\n<\/div>\n<p id=\"fs-idm216506080\">These observations are consistent with (i) the oxidation of elemental copper to yield copper(II) ions, Cu<sup>2+<\/sup><em data-effect=\"italics\">(aq)<\/em>, which impart a blue color to the solution, and (ii) the reduction of silver(I) ions to yield elemental silver, which deposits as a fluffy solid on the copper wire surface. And so, <em data-effect=\"italics\">the direct transfer of electrons from the copper wire to the aqueous silver ions is spontaneous<\/em> under the employed conditions. A summary of this redox system is provided by these equations:<\/p>\n<div id=\"fs-idm479533072\" style=\"padding-left: 40px\" data-type=\"equation\">overall reaction:\u00a0 Cu(<em>s<\/em>) + 2Ag<sup>+<\/sup>(<em>aq<\/em>) \u27f6 Cu<sup>2+<\/sup>(<em>aq<\/em>) + 2Ag(<em>s<\/em>)<\/div>\n<div style=\"padding-left: 40px\" data-type=\"equation\">oxidation half-reaction:\u00a0 Cu(<em>s<\/em>) \u27f6 Cu<sup>2+<\/sup>(<em>aq<\/em>) + 2e<sup>\u2212<\/sup><\/div>\n<div style=\"padding-left: 40px\" data-type=\"equation\">reduction half-reaction: 2Ag<sup>+<\/sup>(<em>aq<\/em>) + 2e<sup>\u2212<\/sup> \u27f6 2Ag(<em>s<\/em>)<\/div>\n<p id=\"fs-idm201862608\">Consider the construction of a device that contains all the reactants and products of a redox system like the one here, but prevents physical contact between the reactants. Direct transfer of electrons is, therefore, prevented; transfer, instead, takes place indirectly through an external circuit that contacts the separated reactants. Devices of this sort are generally referred to as <em data-effect=\"italics\">electrochemical cells<\/em>, and those in which a spontaneous redox reaction takes place are called <strong>galvanic cells<\/strong> (or <strong>voltaic cells<\/strong>).<\/p>\n<p id=\"fs-idm196674112\">A galvanic cell based on the spontaneous reaction between copper and silver(I) is depicted in <a class=\"autogenerated-content\" href=\"#CNX_Chem_17_02_Galvanicel\">(Figure)<\/a>. The cell is comprised of two <strong>half-cells<\/strong>, each containing the redox conjugate pair (\u201ccouple\u201d) of a single reactant. The half-cell shown at the left contains the Cu(0)\/Cu(II) couple in the form of a solid copper foil and an aqueous solution of copper nitrate. The right half-cell contains the Ag(I)\/Ag(0) couple as solid silver foil and an aqueous silver nitrate solution. An external circuit is connected to each half-cell at its solid foil, meaning the Cu and Ag foil each function as an <em data-effect=\"italics\">electrode<\/em>. By definition, the <strong>anode <\/strong>of an electrochemical cell is the electrode at which oxidation occurs (in this case, the Cu foil) and the <strong>cathode <\/strong>is the electrode where reduction occurs (the Ag foil). The redox reactions in a galvanic cell occur only at the interface between each half-cell\u2019s reaction mixture and its electrode. To keep the reactants separate while maintaining charge-balance, the two half-cell solutions are connected by a tube filled with inert electrolyte solution called a <strong>salt bridge<\/strong>. The spontaneous reaction in this cell produces Cu<sup>2+<\/sup> cations in the anode half-cell and consumes Ag<sup>+<\/sup> ions in the cathode half-cell, resulting in a compensatory flow of inert ions from the salt bridge that maintains charge balance. Increasing concentrations of Cu<sup>2+<\/sup> in the anode half-cell are balanced by an influx of NO<sub>3<\/sub><sup>\u2212<\/sup> from the salt bridge, while a flow of Na<sup>+<\/sup> into the cathode half-cell compensates for the decreasing Ag<sup>+<\/sup> concentration.<\/p>\n<p>&nbsp;<\/p>\n<div id=\"CNX_Chem_17_02_Galvanicel\" class=\"scaled-down\">\n<div class=\"bc-figcaption figcaption\">A galvanic cell based on the spontaneous reaction between copper and silver(I) ions.<\/div>\n<p><span id=\"fs-idp20459472\" data-type=\"media\" data-alt=\"This figure contains a diagram of an electrochemical cell. Two beakers are shown. Each is just over half full. The beaker on the left contains a blue solution and is labeled below as \u201c1 M solution of copper (II) nitrate ( C u ( N O subscript 3 ) subscript 2 ).\u201d The beaker on the right contains a colorless solution and is labeled below as \u201c1 M solution of silver nitrate ( A g N O subscript 3 ).\u201d A glass tube in the shape of an inverted U connects the two beakers at the center of the diagram. The tube contents are colorless. The ends of the tubes are beneath the surface of the solutions in the beakers and a small gray plug is present at each end of the tube. The plug in the left beaker is labeled \u201cPorous plug.\u201d At the center of the diagram, the tube is labeled \u201cSalt bridge ( N a N O subscript 3 ). Each beaker shows a metal strip partially submerged in the liquid. The beaker on the left has an orange-brown strip that is labeled \u201cC u anode negative\u201d at the top. The beaker on the right has a silver strip that is labeled \u201cA g cathode positive\u201d at the top. A wire extends from the top of each of these strips to a rectangle indicating \u201cexternal circuit\u201d that is labeled \u201cflow of electrons\u201d with an arrow pointing to the right following. A curved arrow extends from the C u strip into the surrounding solution. The tip of this arrow is labeled \u201cC u superscript 2 plus.\u201d A curved arrow extends from the salt bridge into the beaker on the left into the blue solution. The tip of this arrow is labeled \u201cN O subscript 3 superscript negative.\u201d A curved arrow extends from the solution in the beaker on the right to the A g strip. The base of this arrow is labeled \u201cA g superscript plus.\u201d A curved arrow extends from the colorless solution to salt bridge in the beaker on the right. The base of this arrow is labeled \u201cN O subscript 3 superscript negative.\u201d Just right of the salt bridge in the colorless solution is the label \u201cN a superscript plus.\u201d Just above this region of the tube appears the label \u201cFlow of cations.\u201d Just left of the salt bridge in the blue solution is the label \u201cN O subscript 3 superscript negative.\u201d Just above this region of the tube appears the label \u201cFlow of anions.\u201d\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_17_02_Galvanicel.jpg\" alt=\"This figure contains a diagram of an electrochemical cell. Two beakers are shown. Each is just over half full. The beaker on the left contains a blue solution and is labeled below as \u201c1 M solution of copper (II) nitrate ( C u ( N O subscript 3 ) subscript 2 ).\u201d The beaker on the right contains a colorless solution and is labeled below as \u201c1 M solution of silver nitrate ( A g N O subscript 3 ).\u201d A glass tube in the shape of an inverted U connects the two beakers at the center of the diagram. The tube contents are colorless. The ends of the tubes are beneath the surface of the solutions in the beakers and a small gray plug is present at each end of the tube. The plug in the left beaker is labeled \u201cPorous plug.\u201d At the center of the diagram, the tube is labeled \u201cSalt bridge ( N a N O subscript 3 ). Each beaker shows a metal strip partially submerged in the liquid. The beaker on the left has an orange-brown strip that is labeled \u201cC u anode negative\u201d at the top. The beaker on the right has a silver strip that is labeled \u201cA g cathode positive\u201d at the top. A wire extends from the top of each of these strips to a rectangle indicating \u201cexternal circuit\u201d that is labeled \u201cflow of electrons\u201d with an arrow pointing to the right following. A curved arrow extends from the C u strip into the surrounding solution. The tip of this arrow is labeled \u201cC u superscript 2 plus.\u201d A curved arrow extends from the salt bridge into the beaker on the left into the blue solution. The tip of this arrow is labeled \u201cN O subscript 3 superscript negative.\u201d A curved arrow extends from the solution in the beaker on the right to the A g strip. The base of this arrow is labeled \u201cA g superscript plus.\u201d A curved arrow extends from the colorless solution to salt bridge in the beaker on the right. The base of this arrow is labeled \u201cN O subscript 3 superscript negative.\u201d Just right of the salt bridge in the colorless solution is the label \u201cN a superscript plus.\u201d Just above this region of the tube appears the label \u201cFlow of cations.\u201d Just left of the salt bridge in the blue solution is the label \u201cN O subscript 3 superscript negative.\u201d Just above this region of the tube appears the label \u201cFlow of anions.\u201d\" data-media-type=\"image\/jpeg\" \/><\/span><\/p>\n<\/div>\n<div id=\"fs-idm191852240\" class=\"bc-section section\" data-depth=\"1\">\n<h3 data-type=\"title\"><strong>Cell Notation<\/strong><\/h3>\n<p id=\"fs-idm213246704\">Abbreviated symbolism is commonly used to represent a galvanic cell by providing essential information on its composition and structure. These symbolic representations are called <strong>cell notations<\/strong> or <strong>cell schematics<\/strong>, and they are written following a few guidelines:<\/p>\n<ul id=\"fs-idm66905104\" data-bullet-style=\"bullet\">\n<li>The relevant components of each half-cell are represented by their chemical formulas or element symbols<\/li>\n<li>All interfaces between component phases are represented by vertical parallel lines; if two or more components are present in the same phase, their formulas are separated by commas<\/li>\n<li>By convention, the schematic begins with the anode and proceeds left-to-right identifying phases and interfaces encountered within the cell, ending with the cathode<\/li>\n<\/ul>\n<p id=\"fs-idm178198704\">A verbal description of the cell as viewed from anode-to-cathode is often a useful first-step in writing its schematic. For example, the galvanic cell shown in <a class=\"autogenerated-content\" href=\"#CNX_Chem_17_02_Galvanicel\">(Figure)<\/a> consists of a solid copper anode immersed in an aqueous solution of copper(II) nitrate that is connected via a salt bridge to an aqueous silver(I) nitrate solution, immersed in which is a solid silver cathode. Converting this statement to symbolism following the above guidelines results in the cell schematic:<\/p>\n<div data-type=\"equation\"><\/div>\n<div id=\"fs-idm224675200\" style=\"padding-left: 40px\" data-type=\"equation\">Cu(<em>s<\/em>)\u25021 M Cu(NO<sub>3<\/sub>)<sub>2<\/sub>(<em>aq<\/em>)\u25511 M AgNO<sub>3<\/sub>(<em>aq<\/em>)\u2502Ag(<em>s<\/em>)<\/div>\n<p id=\"fs-idm183571200\">Consider a different galvanic cell (see <a class=\"autogenerated-content\" href=\"#CNX_Chem_17_02_Oxidareduc\">(Figure)<\/a>) based on the spontaneous reaction between solid magnesium and aqueous iron(III) ions:<\/p>\n<div id=\"fs-idm198448336\" style=\"padding-left: 40px\" data-type=\"equation\">net cell reaction:\u00a0 Mg(<em>s<\/em>) + 2Fe<sup>3+<\/sup>(<em>aq<\/em>) \u27f6 Mg<sup>2+<\/sup>(<em>aq<\/em>) + 2Fe<sup>2+<\/sup>(<em>aq<\/em>)<\/div>\n<div style=\"padding-left: 40px\" data-type=\"equation\">oxidation half-reaction:\u00a0 Mg(<em>s<\/em>) \u27f6 Mg<sup>2+<\/sup>(<em>aq<\/em>) + 2e<sup>\u2212<\/sup><\/div>\n<div style=\"padding-left: 40px\" data-type=\"equation\">reduction half-reaction:\u00a0 2Fe<sup>3+<\/sup>(<em>aq<\/em>) + 2e<sup>\u2212<\/sup> \u27f6 2Fe<sup>2+<\/sup>(<em>aq<\/em>)<\/div>\n<p id=\"fs-idm215655008\">In this cell, a solid magnesium anode is immersed in an aqueous solution of magnesium chloride that is connected via a salt bridge to an aqueous solution containing a mixture of iron(III) chloride and iron(II) chloride, immersed in which is a platinum cathode. The cell schematic is then written as<\/p>\n<div id=\"fs-idm198262288\" style=\"padding-left: 40px\" data-type=\"equation\">Mg(<em>s<\/em>)\u25020.1 M MgCl<sub>2<\/sub>(<em>aq<\/em>)\u25510.2 M FeCl<sub>3<\/sub>(<em>aq<\/em>), 0.3 M FeCl<sub>2<\/sub>(<em>aq<\/em>)\u2502Pt(<em>s<\/em>)<\/div>\n<p id=\"fs-idm214418000\">Notice the cathode half-cell is different from the others considered thus far in that its electrode is comprised of a substance (Pt) that is neither a reactant nor a product of the cell reaction. This is required when neither member of the half-cell\u2019s redox couple can reasonably function as an electrode, which must be electrically conductive and in a phase separate from the half-cell solution. In this case, both members of the redox couple are solute species, and so Pt is used as an<strong> inert electrode<\/strong> that can simply provide or accept electrons to redox species in solution. Electrodes constructed from a member of the redox couple, such as the Mg anode in this cell, are called <strong>active electrodes<\/strong>.<\/p>\n<p>&nbsp;<\/p>\n<div id=\"CNX_Chem_17_02_Oxidareduc\" class=\"bc-figure figure\">\n<div class=\"bc-figcaption figcaption\">A galvanic cell based on the spontaneous reaction between magnesium and iron(III) ions.<\/div>\n<p><span id=\"fs-idm141095104\" data-type=\"media\" data-alt=\"This figure contains a diagram of an electrochemical cell. Two beakers are shown. Each is just over half full. The beaker on the left contains a colorless solution. The beaker on the right also contains a colorless solution. A glass tube in the shape of an inverted U connects the two beakers at the center of the diagram. The tube contents are colorless. The ends of the tubes are beneath the surface of the solutions in the beakers and a small gray plug is present at each end of the tube. At the center of the diagram, the tube is labeled \u201cSalt bridge.\u201d Each beaker shows a metal coils submerged in the liquid. The beaker on the left has a thin, gray, coiled strip that is labeled \u201cM g anode.\u201d The beaker on the right has a black wire that is oriented horizontally and coiled up in a spring-like appearance that is labeled \u201cP t cathode.\u201d Below the coil is the label \u201cF e superscript 3 plus\u201d with a curved right arrowing pointing from that to the label \u201cF e superscript 2 plus.\u201d A wire extends across the top of the diagram that connects the ends of the M g strip and P t cathode just above the opening of each beaker. At the center of the wire above the two beakers is a rectangle labeled \u201cexternal circuit.\u201d Above the rectangle is the label \u201cflow of electrons\u201d followed by a right pointing arrow. An arrow points down and to the right from the label \u201cN a superscript plus\u201d at the upper right region of the salt bride. An arrow points down and to the left from the label \u201cC l superscript negative\u201d at the upper left region of the salt bride. Below the graylug at the left end of the salt bridge in the surrounding solution in the left beaker is the label \u201cC l superscript negative.\u201d Below the coil on this side is a right arrow and the label \u201cM g superscript 2 plus.\u201d The label \u201c0.1 M M g C l subscript 2\u201d appears beneath the left beaker. The label \u201c0.2 M F e C l subscript 3 and 0.3 M F e C l subscript 2.\u201d appears beneath the right beaker.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_17_02_Oxidareduc.jpg\" alt=\"This figure contains a diagram of an electrochemical cell. Two beakers are shown. Each is just over half full. The beaker on the left contains a colorless solution. The beaker on the right also contains a colorless solution. A glass tube in the shape of an inverted U connects the two beakers at the center of the diagram. The tube contents are colorless. The ends of the tubes are beneath the surface of the solutions in the beakers and a small gray plug is present at each end of the tube. At the center of the diagram, the tube is labeled \u201cSalt bridge.\u201d Each beaker shows a metal coils submerged in the liquid. The beaker on the left has a thin, gray, coiled strip that is labeled \u201cM g anode.\u201d The beaker on the right has a black wire that is oriented horizontally and coiled up in a spring-like appearance that is labeled \u201cP t cathode.\u201d Below the coil is the label \u201cF e superscript 3 plus\u201d with a curved right arrowing pointing from that to the label \u201cF e superscript 2 plus.\u201d A wire extends across the top of the diagram that connects the ends of the M g strip and P t cathode just above the opening of each beaker. At the center of the wire above the two beakers is a rectangle labeled \u201cexternal circuit.\u201d Above the rectangle is the label \u201cflow of electrons\u201d followed by a right pointing arrow. An arrow points down and to the right from the label \u201cN a superscript plus\u201d at the upper right region of the salt bride. An arrow points down and to the left from the label \u201cC l superscript negative\u201d at the upper left region of the salt bride. Below the graylug at the left end of the salt bridge in the surrounding solution in the left beaker is the label \u201cC l superscript negative.\u201d Below the coil on this side is a right arrow and the label \u201cM g superscript 2 plus.\u201d The label \u201c0.1 M M g C l subscript 2\u201d appears beneath the left beaker. The label \u201c0.2 M F e C l subscript 3 and 0.3 M F e C l subscript 2.\u201d appears beneath the right beaker.\" data-media-type=\"image\/jpeg\" \/><\/span><\/p>\n<\/div>\n<div id=\"fs-idm168909584\" class=\"textbox textbox--examples\" data-type=\"example\">\n<p id=\"fs-idm148208960\"><strong>Writing Galvanic Cell Schematics <\/strong><\/p>\n<p>A galvanic cell is fabricated by connecting two half-cells with a salt bridge, one in which a chromium wire is immersed in a 1 M CrCl<sub>3<\/sub> solution and another in which a copper wire is immersed in 1 M CuCl<sub>2<\/sub>. Assuming the chromium wire functions as an anode, write the schematic for this cell along with equations for the anode half-reaction, the cathode half-reaction, and the overall cell reaction.<\/p>\n<p id=\"fs-idp124889088\"><strong>Solution:<\/strong><\/p>\n<p>Since the chromium wire is stipulated to be the anode, the schematic begins with it and proceeds left-to-right, symbolizing the other cell components until ending with the copper wire cathode:<\/p>\n<div id=\"fs-idm184234832\" style=\"padding-left: 40px\" data-type=\"equation\">Cr(<em>s<\/em>)\u25021 M CrCl<sub>3<\/sub>(<em>aq<\/em>)\u25511 M CuCl<sub>2<\/sub>(<em>aq<\/em>)\u2502Cu(<em>s<\/em>)<\/div>\n<div data-type=\"equation\"><\/div>\n<p id=\"fs-idm191652416\">The half-reactions for this cell are<\/p>\n<div id=\"fs-idm177989472\" style=\"padding-left: 40px\" data-type=\"equation\">anode (oxidation):\u00a0 Cr(s) \u27f6 Cr<sup>3+<\/sup>(<em>aq<\/em>) + 3e<sup>\u2212<\/sup><\/div>\n<div style=\"padding-left: 40px\" data-type=\"equation\">cathode (oxidation):\u00a0 Cu<sup>2+<\/sup>(<em>aq<\/em>) + 2e<sup>\u2212<\/sup> \u27f6 Cu(<em>s<\/em>)<\/div>\n<p id=\"fs-idm206725184\">Multiplying to make the number of electrons lost by Cr and gained by Cu<sup>2+<\/sup> equal yields<\/p>\n<div id=\"fs-idm479522256\" data-type=\"equation\">\n<div id=\"fs-idm177989472\" style=\"padding-left: 40px\" data-type=\"equation\">anode (oxidation):\u00a0 2Cr(s) \u27f6 2Cr<sup>3+<\/sup>(<em>aq<\/em>) + 6e<sup>\u2212<\/sup><\/div>\n<div style=\"padding-left: 40px\" data-type=\"equation\">cathode (oxidation):\u00a0 3Cu<sup>2+<\/sup>(<em>aq<\/em>) + 6e<sup>\u2212<\/sup> \u27f6 3Cu(<em>s<\/em>)<\/div>\n<\/div>\n<p id=\"fs-idm480712000\">Adding the half-reaction equations and simplifying yields an equation for the cell reaction:<\/p>\n<div id=\"fs-idm183688400\" style=\"padding-left: 40px\" data-type=\"equation\">2Cr(<em>s<\/em>) + 3Cu<sup>2+<\/sup>(<em>aq<\/em>) \u27f6 2Cr<sup>3+<\/sup>(<em>aq<\/em>) + 3Cu(<em>s<\/em>)<\/div>\n<div data-type=\"equation\"><\/div>\n<div data-type=\"equation\"><\/div>\n<p id=\"fs-idm199393680\"><strong>Check Your Learning:<\/strong><\/p>\n<p>Omitting solute concentrations and spectator ion identities, write the schematic for a galvanic cell whose net cell reaction is shown below.<\/p>\n<div id=\"fs-idm477306416\" style=\"padding-left: 40px\" data-type=\"equation\">Sn<sup>4+<\/sup>(<em>aq<\/em>) + Zn(<em>s<\/em>) \u27f6 Sn<sup>2+<\/sup>(<em>aq<\/em>) + Zn<sup>2+<\/sup>(<em>aq<\/em>)<\/div>\n<div data-type=\"equation\"><\/div>\n<div id=\"fs-idp13471872\" data-type=\"note\">\n<div data-type=\"title\"><strong>Answer:<\/strong><\/div>\n<p id=\"fs-idm479605136\" style=\"padding-left: 40px\">Zn(<em>s<\/em>)\u2502Zn<sup>2+<\/sup>(<em>aq<\/em>)\u2551Sn<sup>4+<\/sup>(<em>aq<\/em>), Sn<sup>2+<\/sup>(<em>aq<\/em>)\u2502Pt(<em>s<\/em>)<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"fs-idm89705136\" class=\"summary\" data-depth=\"1\">\n<h3 data-type=\"title\"><strong>Key Concepts and Summary<\/strong><\/h3>\n<p id=\"fs-idm71248464\">Galvanic cells are devices in which a spontaneous redox reaction occurs indirectly, with the oxidant and reductant redox couples contained in separate half-cells. Electrons are transferred from the reductant (in the anode half-cell) to the oxidant (in the cathode half-cell) through an external circuit, and inert solution phase ions are transferred between half-cells, through a salt bridge, to maintain charge neutrality. The construction and composition of a galvanic cell may be succinctly represented using chemical formulas and others symbols in the form of a cell schematic (cell notation).<\/p>\n<\/div>\n<div id=\"fs-idm190362800\" class=\"exercises\" data-depth=\"1\">\n<div id=\"fs-idm33124048\" data-type=\"exercise\">\n<div id=\"fs-idm178777776\" data-type=\"problem\">\n<p id=\"fs-idp7124096\">\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox shaded\" data-type=\"glossary\">\n<h3 data-type=\"glossary-title\"><strong>Glossary<\/strong><\/h3>\n<dl id=\"fs-idp13398640\">\n<dt>active electrode<\/dt>\n<dd id=\"fs-idp54206496\">electrode that participates as a reactant or product in the oxidation-reduction reaction of an electrochemical cell; the mass of an active electrode changes during the oxidation-reduction reaction<\/dd>\n<\/dl>\n<dl id=\"fs-idp4652784\">\n<dt>anode<\/dt>\n<dd id=\"fs-idp20601168\">electrode in an electrochemical cell at which oxidation occurs<\/dd>\n<\/dl>\n<dl id=\"fs-idm120688224\">\n<dt>cathode<\/dt>\n<dd id=\"fs-idm171511936\">electrode in an electrochemical cell at which reduction occurs<\/dd>\n<\/dl>\n<dl id=\"fs-idm139905600\">\n<dt>cell notation (schematic)<\/dt>\n<dd id=\"fs-idm155391072\">symbolic representation of the components and reactions in an electrochemical cell<\/dd>\n<\/dl>\n<dl id=\"fs-idm153779040\">\n<dt>cell potential (<em data-effect=\"italics\">E<\/em><sub>cell<\/sub>)<\/dt>\n<dd id=\"fs-idm191155536\">difference in potential of the cathode and anode half-cells<\/dd>\n<\/dl>\n<dl id=\"fs-idm159189392\">\n<dt>galvanic (voltaic) cell<\/dt>\n<dd id=\"fs-idm148308224\">electrochemical cell in which a spontaneous redox reaction takes place; also called a <em data-effect=\"italics\">voltaic cell<\/em><\/dd>\n<\/dl>\n<dl id=\"fs-idm19899136\">\n<dt>inert electrode<\/dt>\n<dd id=\"fs-idm201925328\">electrode that conducts electrons to and from the reactants in a half-cell but that is not itself oxidized or reduced<\/dd>\n<\/dl>\n<\/div>\n","protected":false},"author":1392,"menu_order":3,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[48],"contributor":[],"license":[],"class_list":["post-877","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":870,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapters\/877","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/wp\/v2\/users\/1392"}],"version-history":[{"count":7,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapters\/877\/revisions"}],"predecessor-version":[{"id":2185,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapters\/877\/revisions\/2185"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/parts\/870"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapters\/877\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/wp\/v2\/media?parent=877"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapter-type?post=877"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/wp\/v2\/contributor?post=877"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/wp\/v2\/license?post=877"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}