Skip to ContentGo to accessibility pageKeyboard shortcuts menu
OpenStax Logo
Chemistry 2e

Chapter 17

Chemistry 2eChapter 17


(a) reduction; (b) oxidation; (c) oxidation; (d) reduction


(a) F2+Ca2F+Ca2+;F2+Ca2F+Ca2+; (b) Cl2+2Li2Li++2Cl;Cl2+2Li2Li++2Cl; (c) 3Br2+2Fe2Fe3++6Br;3Br2+2Fe2Fe3++6Br; (d) MnO4+4H++3Ag3Ag++MnO2+2H2OMnO4+4H++3Ag3Ag++MnO2+2H2O


Oxidized: (a) Sn2+; (b) Hg; (c) Al; reduced: (a) H2O2; (b) PbO2; (c) Cr2O72−;Cr2O72−; oxidizing agent: (a) H2O2; (b) PbO2; (c) Cr2O72−;Cr2O72−; reducing agent: (a) Sn2+; (b) Hg; (c) Al


Oxidized = reducing agent: (a) SO32−;SO32−; (b) Mn(OH)2; (c) H2; (d) Al; reduced = oxidizing agent: (a) Cu(OH)2; (b) O2; (c) NO3;NO3; (d) CrO42−CrO42−


In basic solution, [OH] > 1 ×× 10−7 M > [H+]. Hydrogen ion cannot appear as a reactant because its concentration is essentially zero. If it were produced, it would instantly react with the excess hydroxide ion to produce water. Thus, hydrogen ion should not appear as a reactant or product in basic solution.


(a) Mg(s)Mg2+(aq)Ni2+(aq)Ni(s);Mg(s)Mg2+(aq)Ni2+(aq)Ni(s); (b) Cu(s)Cu2+(aq)Ag+(aq)Ag(s);Cu(s)Cu2+(aq)Ag+(aq)Ag(s); (c) Mn(s)Mn2+(aq)Sn2+(aq)Sn(s);Mn(s)Mn2+(aq)Sn2+(aq)Sn(s); (d) Pt(s)Cu+(aq), Cu2+(aq)Au3+(aq)Au(s)Pt(s)Cu+(aq), Cu2+(aq)Au3+(aq)Au(s)


(a) Mg(s)+Cu2+(aq)Mg2+(aq)+Cu(s);Mg(s)+Cu2+(aq)Mg2+(aq)+Cu(s); (b) 2Ag+(aq)+Ni(s)Ni2+(aq)+2Ag(s)2Ag+(aq)+Ni(s)Ni2+(aq)+2Ag(s)


Species oxidized = reducing agent: (a) Al(s); (b) NO(g); (c) Mg(s); and (d) MnO2(s); Species reduced = oxidizing agent: (a) Zr4+(aq); (b) Ag+(aq); (c) SiO32−(aq)SiO32−(aq); and (d) ClO3(aq)ClO3(aq)


Without the salt bridge, the circuit would be open (or broken) and no current could flow. With a salt bridge, each half-cell remains electrically neutral and current can flow through the circuit.


Active electrodes participate in the oxidation-reduction reaction. Since metals form cations, the electrode would lose mass if metal atoms in the electrode were to oxidize and go into solution. Oxidation occurs at the anode.


(a) +2.115 V (spontaneous); (b) +0.4626 V (spontaneous); (c) +1.048 V (spontaneous); (d) +0.727 V (spontaneous)


3Cu(s)+2Au3+(aq)3Cu2+(aq)+2Au(s);3Cu(s)+2Au3+(aq)3Cu2+(aq)+2Au(s); +1.16 V; spontaneous


3Cd(s)+2Al3+(aq)3Cd2+(aq)+2Al(s);3Cd(s)+2Al3+(aq)3Cd2+(aq)+2Al(s); −1.259 V; nonspontaneous


(a) 0 kJ/mol; (b) −83.7 kJ/mol; (c) +235.3 kJ/mol


(a) standard cell potential: 1.50 V, spontaneous; cell potential under stated conditions: 1.43 V, spontaneous; (b) standard cell potential: 1.405 V, spontaneous; cell potential under stated conditions: 1.423 V, spontaneous; (c) standard cell potential: −2.749 V, nonspontaneous; cell potential under stated conditions: −2.733 V, nonspontaneous


(a) 1.7 ×× 10−10; (b) 2.6 ×× 10−21; (c) 4.693 ×× 1021; (d) 1.0 ×× 10−14


(a) anode: Cu(s)Cu2+(aq)+2eEanode°=0.34 Vcathode:2×(Ag+(aq)+eAg(s))Ecathode°=0.7996 V;anode: Cu(s)Cu2+(aq)+2eEanode°=0.34 Vcathode:2×(Ag+(aq)+eAg(s))Ecathode°=0.7996 V; (b) 3.5 ×× 1015; (c) 5.6 ×× 10−9 M


Batteries are self-contained and have a limited supply of reagents to expend before going dead. Alternatively, battery reaction byproducts accumulate and interfere with the reaction. Because a fuel cell is constantly resupplied with reactants and products are expelled, it can continue to function as long as reagents are supplied.


Ecell, as described in the Nernst equation, has a term that is directly proportional to temperature. At low temperatures, this term is decreased, resulting in a lower cell voltage provided by the battery to the device—the same effect as a battery running dead.


Mg and Zn


Both examples involve cathodic protection. The (sacrificial) anode is the metal that corrodes (oxidizes or reacts). In the case of iron (−0.447 V) and zinc (−0.7618 V), zinc has a more negative standard reduction potential and so serves as the anode. In the case of iron and copper (0.34 V), iron has the smaller standard reduction potential and so corrodes (serves as the anode).


While the reduction potential of lithium would make it capable of protecting the other metals, this high potential is also indicative of how reactive lithium is; it would have a spontaneous reaction with most substances. This means that the lithium would react quickly with other substances, even those that would not oxidize the metal it is attempting to protect. Reactivity like this means the sacrificial anode would be depleted rapidly and need to be replaced frequently. (Optional additional reason: fire hazard in the presence of water.)


(a) mass Ca=69.1 gmass Cl2=122 g;mass Ca=69.1 gmass Cl2=122 g; (b) mass Li=23.9 gmass H2=3.48 g;mass Li=23.9 gmass H2=3.48 g; (c) mass Al=31.0 gmass Cl2=122 g;mass Al=31.0 gmass Cl2=122 g; (d) mass Cr=59.8 gmass Br2=276 gmass Cr=59.8 gmass Br2=276 g


0.79 L

Order a print copy

As an Amazon Associate we earn from qualifying purchases.


This book may not be used in the training of large language models or otherwise be ingested into large language models or generative AI offerings without OpenStax's permission.

Want to cite, share, or modify this book? This book uses the Creative Commons Attribution License and you must attribute OpenStax.

Attribution information
  • If you are redistributing all or part of this book in a print format, then you must include on every physical page the following attribution:
    Access for free at
  • If you are redistributing all or part of this book in a digital format, then you must include on every digital page view the following attribution:
    Access for free at
Citation information

© Jan 8, 2024 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License . The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.