Make a sketch of an electrochemical cell with the overall reaction shown here. Label the

What is a fuel-cell electric vehicle?

What kinds of molecules are often involved in smell?

Define oxidation and reduction with respect to: (a) oxygen (b) electrons (c) oxidation state

What is an oxidizing agent? What is a reducing agent?

Good oxidizing agents have a strong tendency to _____ electrons in reactions.

Good reducing agents have a strong tendency to _____ electrons in reactions.

What is the oxidation state of a free element? Of a monoatomic ion?

For a neutral molecule, the oxidation states of the individual atoms must add up to _____.

For an ion, the oxidation states of the individual atoms must add up to _____.

In their compounds, elements have oxidation states equal to _____. Are there exceptions to this rule? Explain.

In a redox reaction, an atom that undergoes an increase in oxidation state is _____. An atom that undergoes a decrease in oxidation state is _____.

How does hydrogen peroxide change hair color?

When balancing redox equations, the number of electrons lost in the oxidation half-reaction must _____ the number of electrons gained in the reduction half-reaction.

When balancing aqueous redox reactions, oxygen is balanced using _____, and hydrogen is balanced using _____.

When balancing aqueous redox reactions, charge is balanced using _____.

When balancing aqueous redox reactions in basic media, hydrogen ions are neutralized using _____.

Are metals at the top of the activity series the most reactive or least reactive?

Are metals at the top of the activity series the easiest or hardest to oxidize?

Are metals at the bottom of the activity series most likely or least likely to lose electrons?

Any half-reaction in the activity series will be spontaneous when paired with the reverse of any half-reaction _____ it.

What is electrical current? Explain how a simple battery creates electrical current.

How can you use the activity series to determine whether a metal will dissolve in acids such as HCl or HBr?

Oxidation occurs at the _____ of an electrochemical cell.

Reduction occurs at the _____ of an electrochemical cell.

Explain the role of a salt bridge in an electrochemical cell.

A high voltage in an electrochemical cell is analogous to _____ in a river.

Describe a common dry-cell battery. Include equations for the anode and cathode reactions.

Describe a lead-acid storage battery. Include equations for the anode and cathode reactions.

Describe a fuel cell. Include equations for the anode and cathode reactions of the hydrogen–oxygen fuel cell.

What is electrolysis? Why is it useful?

What is corrosion? List reactions for the corrosion of iron.

How can rust be prevented?

Which substance is oxidized in each reaction? (a) \(2 \mathrm{H}_2(g)+\mathrm{O}_2(g) \longrightarrow 2 \mathrm{H}_2 \mathrm{O}(l)\) (b) \(4 \mathrm{Al}(s)+3 \mathrm{O}_2(g) \longrightarrow 2 \mathrm{Al}_2 \mathrm{O}_3(s)\) (c) \(2 \mathrm{Al}(s)+3 \mathrm{Cl}_2(g) \longrightarrow 2 \mathrm{AlCl}_3(s)\)

Which substance is oxidized in each reaction? (a) \(2~ \mathrm{Zn}(s)+\mathrm O_2(g) \longrightarrow 2~ \mathrm{ZnO}(s)\) (b) \(\mathrm{CH_4}(g)+2~ \mathrm{O_2}(g) \longrightarrow \mathrm{CO_2}(g)+2~ \mathrm{H_2O}(g)\) (c) \(\mathrm{Sr}(s)+\mathrm{F_2}(g) \longrightarrow \mathrm{SrF_2}(s)\) Equation Transcription: Text Transcription: 2 Zn(s)+O_2(g) rightarrow 2 ZnO(s) CH4(g)+2 O_2(g)CO_2(g) rightarrow 2 H_2O(g) Sr(s)+F_2(g) rightarrow SrF_2(s)

For each reaction, identify the substance being oxidized and the substance being reduced. (a) \(\mathrm{2~ Sr}(s)+\mathrm{O_2}(g) \longrightarrow 2~ \mathrm{SrO}(s)\) (b) \(\mathrm{Ca}(s)+\mathrm{Cl_2}(g) \longrightarrow \mathrm{CaCl_2}(s)\) (c) \(\mathrm{Ni}^{2+}(aq)+\mathrm{Mg}(s) \longrightarrow \mathrm{Mg}^{2+}(aq)+\mathrm{Ni}(s)\) Equation Transcription: Text Transcription: 2 Sr(s)+O_2(g) rightarrow 2 SrO(s) Ca(s)+Cl_2(g) rightarrow CaCl_2(s) Ni^{2+}(aq)+Mg(s) rightarrow Mg^{2+}(aq)+Ni(s)

Problem 36P For each reaction, identify tine substance being oxidized and the substance being reduced. (a) Mg(s) + Br2(g) ? MgBr2(s) (b) 2 Cr3+(aq) + 3 Mn(s) ? 2 Cr(s) + 3 Mn2+ (aq) (c) 2 H+ (aq) + Ni(s) ? H2(g) + Ni2+ (aq)

For each of the reactions in Problem 35, identify the oxidizing agent and the reducing agent. Problem 35: (a) \(\mathrm{2~ Sr}(s)+\mathrm{O_2}(g) \longrightarrow 2~ \mathrm{SrO}(s)\) (b) \(\mathrm{Ca}(s)+\mathrm{Cl_2}(g) \longrightarrow \mathrm{CaCl_2}(s)\) (c) \(\mathrm{Ni}^{2+}(aq)+\mathrm{Mg}(s) \longrightarrow \mathrm{Mg}^{2+}(aq)+\mathrm{Ni}(s)\) Equation Transcription: Text Transcription: 2 Sr(s)+O_2(g) rightarrow 2 SrO(s) Ca(s)+Cl_2(g) rightarrow CaCl_2(s) Ni^{2+}(aq)+Mg(s) rightarrow Mg^{2+}(aq)+Ni(s)

For each of the reactions in Problem 36 , identify the oxidizing agent and the reducing agent. Problem 36: (a) \(\mathrm{Mg}(s)+\mathrm{Br}_2(g) \longrightarrow \mathrm{MgBr}_2(s)\) (b) \(2 \mathrm{Cr}^{3+}(a q)+3 \mathrm{Mn}(s) \longrightarrow 2 \mathrm{Cr}(s)+3 \mathrm{Mn}^{2+}(a q)\) (c) \(2 \mathrm{H}^{+}(a q)+\mathrm{Ni}(s) \longrightarrow \mathrm{H}_2(g)+\mathrm{Ni}^{2+}(a q)\)

Based on periodic trends, which elements would you expect to be good oxidizing agents? (a) potassium (b) fluorine (c) iron (d) chlorine

Based on periodic trends, which elements would you expect to be good oxidizing agents? (a) oxygen (b) bromine (c) lithium (d) sodium

Based on periodic trends, which elements in Problem 39 (in their elemental form) would you expect to be good reducing agents? (a) potassium (b) fluorine (c) iron (d) chlorine

Based on periodic trends, which elements in Problem 40 (in their elemental form) would you expect to be good reducing agents? (a) oxygen (b) bromine (c) lithium (d) sodium

For each redox reaction, identify the substance being oxidized, the substance being reduced, the oxidizing agent, and the reducing agent. (a) \(\mathrm{N}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2~ \mathrm{NO}(g)\) (b) \(2~ \mathrm{CO}(g)+\mathrm{O}_{2}(g) \longrightarrow 2~ \mathrm{CO}_{2}(g)\) (c) \(\mathrm{SbCl}_{3}(g)+\mathrm{Cl}_{2}(g) \longrightarrow \mathrm{SbCl}_{5}(g)\) Equation Transcription: Text Transcription: N_2(g)+O_2(g) rightarrow 2 NO(g) 2 CO(g)+O_2(g) rightarrow 2 CO_2(g) SbCl_3(g)+Cl_2(g) rightarrow SbCl_5(g)

Assign an oxidation state to each element or ion. (a) V (b) \(\mathrm{Mg^{2+}}\) (c) \(\mathrm{Cr^{3+}}\) (d) \(\mathrm{O_2}\) Equation Transcription: Text Transcription: Mg^{2+} Cr^{3+} O_2

Assign an oxidation state to each atom in each compound. (a) \(\mathrm{NaCl}\) (b) \(\mathrm{CaF}_2\) (c) \(\mathrm{SO}_2\) (d) \(\mathrm{H}_2 \mathrm{~S}\)

What is the oxidation state of Cl in each ion? (a) \(\mathrm{ClO^-}\) (b) \(\mathrm{ClO_2^{~-}}\) (c) \(\mathrm{ClO_3^{~-}}\) (d) \(\mathrm{ClO_4^{~-}}\) Equation Transcription: Text Transcription: ClO^- ClO_2^- ClO_3^- ClO_4^-

Assign an oxidation state to each atom in each polyatomic ion. (a) \(\mathrm{CrO_4^{~2-}}\) (b) \(\mathrm{Cr_2O_7^{~2-}}\) (c) \(\mathrm{PO_4^{~3-}}\) (d) \(\mathrm{MnO_4^{~-}}\) Equation Transcription: Text Transcription: CrO_4^{2-} Cr_2O_7^{2-} PO_4^{3-} MnO_4^{-}

Balance each redox reaction using the half-reaction method. (a) \(\mathrm{Zn}(s)+\mathrm{Sn}^{2+}(a q) \longrightarrow \mathrm{Zn}^{2+}(a q)+\mathrm{Sn}(s)\) (b) \(\mathrm{Mg}(s)+\mathrm{Cr}^{3+}(a q) \longrightarrow \mathrm{Mg}^{2+}(a q)+\mathrm{Cr}(s)\) (c) \(\mathrm{Al}(s)+\mathrm{Ag}^{+}(a q) \longrightarrow \mathrm{Al}^{3+}(a q)+\mathrm{Ag}(s)\) Equation Transcription: Text Transcription: Zn(s)+Sn^{2+}(aq) rightarrow Zn^{2+}(aq)+Sn(s) Mg(s)+Cr^{3+}(aq) rightarrow Mg^{2+}(aq)+Cr(s) Al(s)+Ag+(aq) rightarrow Al^{3+}(aq)+Ag(s)

Problem 83P Which metals dissolve in HCl? For those metals that do dissolve, write a balanced redox reaction showing what happens when the metal dissolves. (a) Ag (b) Fe (c) Cu (d) Al

Problem 93P Which metal, if coated onto iron, would prevent the corrosion of iron? (a) Zn (b) Sn (c) Mn

Consider the molecular view of an electrochemical cell involving the overall reaction:

For each redox reaction, identify the substance being oxidized, the substance being reduced, the oxidizing agent, and the reducing agent. (a) \(\mathrm{H}_{2}(g)+\mathrm{I}_{2}(g) \longrightarrow 2~ \mathrm{HI}(g)\) (b) \(\mathrm{CO}(g)+\mathrm{H}_{2}(g) \longrightarrow \mathrm{C}(s)+\mathrm{H}_{2} \mathrm{O}(g)\) (c) \(2~ \mathrm{Al}(s)+6~ \mathrm{H}^{+}(a q) \longrightarrow 2~ \mathrm{Al}^{3+}(a q)+3~ \mathrm{H}_{2}(g)\) Equation Transcription: Text Transcription: H_2(g)+I_2(g) rightarrow 2 HI(g) CO(g)+H_2(g) rightarrow C(s)+H_2O(g) 2 Al(s)+6 H^+(aq) rightarrow 2 Al^3+(aq)+3 H_2(g)

Assign an oxidation state to each element or ion. (a) Ne (b) \(\mathrm{Br_2}\) (c) \(\mathrm{Cu^+}\) (d) \(\mathrm{Fe^{3+}}\) Equation Transcription: Text Transcription: Br_2 Cu^+ Fe^{3+}

Assign an oxidation state to each atom in each compound. (a) \(\mathrm{CH_4}\) (b) \(\mathrm{CH_2Cl_2}\) (c) \(\mathrm{CuCl_2}\) (d) HI Equation Transcription: Text Transcription: CH_4 CH_2Cl_2 CuCl_2

What is the oxidation state of nitrogen in each compound? (a) NO (b) \(\mathrm{NO_2}\) (c) \(\mathrm{N_2O}\) Equation Transcription: Text Transcription: NO_2 N_2O

What is the oxidation state of Cr in each compound? (a) CrO (b) \(\mathrm{CrO_3}\) (c) \(\mathrm{Cr_2O_3}\)

Assign an oxidation state to each atom in each polyatomic ion. (a) \(\mathrm{CO_3^{~2-}}\) (b) \(\mathrm{OH^-}\) (c) \(\mathrm{NO_3^{~-}}\) (d) \(\mathrm{NO_2^{~-}}\) Equation Transcription: Text Transcription: CO_3^{2-} OH^- NO_3^- NO_2^-

Assign an oxidation state to each element in each reaction and use the change in oxidation state to determine which element is being oxidized and which element is being reduced. (a) \(\mathrm{CH}_{4}(g)+2~ \mathrm{H}_{2} \mathrm{S}(g) \longrightarrow \mathrm{CS}_{2}(g)+4~ \mathrm{H}_{2}(g)\) (b) \(2~ \mathrm{H}_{2} \mathrm{~S}(g) \longrightarrow 2~ \mathrm{H}_{2}(g)+\mathrm{S}_{2}(g)\) (c) \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(s)+6~ \mathrm{O}_{2}(g) \longrightarrow 6~ \mathrm{CO}_{2}(g)+6~ \mathrm{H}_{2} \mathrm{O}(g)\) (d) \(\mathrm{C}_{2} \mathrm{H}_{4}(g)+\mathrm{Cl}_{2}(g) \longrightarrow \mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Cl}_{2}(g)\) Equation Transcription: Text Transcription: CH_4(g)+2 H_2S(g) rightarrow CS_2(g)+4 H_2(g) 2 H_2S(g) rightarrow 2 H_2(g)+S_2(g) C_6H_{12}O_6(s)+6 O_2(g) rightarrow 6 CO_2(g)+6 H_2O(g) C_2H_4(g)+Cl_2(g) rightarrow C_2H_4Cl_2(g)

Use oxidation states to identify the oxidizing agent and the reducing agent in the redox reaction. \(2~ \mathrm{Na}(s)+2~ \mathrm{H_2O}(l) \longrightarrow 2~ \mathrm{NaOH}(aq)+\mathrm{H_2}(g)\) Equation Transcription: Text Transcription: 2 Na(s)+2 H_2O(l) rightarrow 2 NaOH(aq)+H_2(g)

Use oxidation states to identify the oxidizing agent and the reducing agent in the redox reaction. \(\mathrm N_2(g)+3~ \mathrm H_2(g) \longrightarrow 2~ \mathrm{NH_3}(g)\)

Balance each redox reaction using the half-reaction method. (a) \(\mathrm{K}(s)+\mathrm{Cr}^{3+}(a q) \longrightarrow \mathrm{Cr}(s)+\mathrm{K}^{+}(a q)\) (b) \(\mathrm{Mg}(s)+\mathrm{Ag}^{+}(a q) \longrightarrow \mathrm{Mg}^{2+}(a q)+\mathrm{Ag}(s)\) (c) \(\mathrm{Al}(s)+\mathrm{Fe}^{2+}(a q) \longrightarrow \mathrm{Al}^{3+}(a q)+\mathrm{Fe}(s)\) Equation Transcription: Text Transcription: K(s)+Cr^{3+}(aq) rightarrow Cr(s)+K^{+}(aq) Mg(s)+Ag^{+}(aq) rightarrow Mg^{2+}(aq)+Ag(s) Al(s)+Fe^{2+}(aq) rightarrow Al^{3+}(aq)+Fe(s)

Classify each half-reaction occurring in acidic aqueous solution as an oxidation or a reduction and balance the half reaction. (a) \(\mathrm{MnO}_{4}^{~-}(a q) \longrightarrow \mathrm{Mn}^{2+}(a q)\) (b) \(\mathrm{Pb}^{2+}(a q) \longrightarrow \mathrm{PbO}_{2}(s)\) (c) \(\mathrm{IO}_{3}^{~-}(a q) \longrightarrow \mathrm{I}_{2}(s)\) (d) \(\mathrm{SO}_{2}(g) \rightarrow \mathrm{SO}_{4}^{~2-}(a q)\) Equation Transcription: Text Transcription: MnO_4^-(aq) rightarrow Mn^{2+}(aq) Pb^{2+}(aq) rightarrow PbO_2(s) IO_3^-(aq) rightarrow I_2(s) SO_2(g) rightarrow SO_4^{2-}(aq)

Classify each half-reaction occurring in acidic aqueous solution as an oxidation or a reduction and balance the half reaction. (a) \(\mathrm{S}(s) \longrightarrow \mathrm{H}_{2} \mathrm{S}(g)\) (b) \(\mathrm{S}_{2} \mathrm{O}_{8}^{~2-}(a q) \longrightarrow 2~ \mathrm{SO}_{4}^{~2-}(a q)\) (c) \(\mathrm{Cr}_{2} \mathrm{O}_{7}^{~2-}(a q) \longrightarrow \mathrm{Cr}^{3+}(a q)\) (d) \(\mathrm{NO}(g) \longrightarrow \mathrm{NO}_{3}^{~-}(a q)\) Equation Transcription: Text Transcription: S(s) rightarrow H_2S(g) S_2O_8^{2-}(aq) rightarrow 2 SO_4^{2-}(aq) Cr_2O_7^{2-}(aq) rightarrow Cr^{3+}(aq) NO(g) rightarrow NO_3^-(aq)

Use the half-reaction method to balance each redox reaction occurring in acidic aqueous solution. (a) \(\mathrm{PbO}_{2}(s)+\mathrm{I}^{-}(a q) \longrightarrow \mathrm{Pb}^{2+}(a q)+\mathrm{I}_{2}(s)\) (b) \(\mathrm{SO}_{3}^{~2-}(a q)+\mathrm{MnO}_{4}^{-}(a q) \longrightarrow \mathrm{SO}_{4}^{~2-}(a q)+\mathrm{Mn}^{2+}(a q)\) (c) \(\mathrm{S}_{2} \mathrm{O}_{3}^{~2-}(a q)+\mathrm{Cl}_{2}(g) \longrightarrow \mathrm{SO}_{4}^{~2-}(a q)+\mathrm{Cl}^{-}(a q)\) Equation Transcription: Text Transcription: PbO_2(s)+I-(aq) rightarrow Pb_2+(aq)+I2(s) SO_3^2-(aq)+MnO_4- rightarrow SO_4^2-(aq)+Mn^2+(aq) S2O_3^2-(aq)+Cl_2(g) rightarrow SO_4^2-(aq)+Cl^-(aq)

Use the half-reaction method to balance each redox reaction occurring in acidic aqueous solution. (a) \(\mathrm{I}^{-}(a q)+\mathrm{NO}_{2}^{~-}(a q) \longrightarrow \mathrm{I}_{2}(s)+\mathrm{NO}(g)\) (b) \(\mathrm{BrO}_{3}^{~-}(a q)+\mathrm{N}_{2} \mathrm{H}_{4}(g) \longrightarrow \mathrm{Br}^{-}(a q)+\mathrm{N}_{2}(g)\) (c) \(\mathrm{NO}_{3}^{~-}(a q)+\mathrm{Sn}^{2+}(a q) \longrightarrow \mathrm{Sn}^{4+}(a q)+\mathrm{NO}(g)\) Equation Transcription: Text Transcription: I^-(aq)+NO_2^-(aq) rightarrow I_2(s)+NO(g) BrO_3^-(aq)+N_2H_4(g) rightarrow Br^-(aq)+N_2(g) NO_3^-(aq)+ Sn_2^+(aq) rightarrow Sn^4+(aq)+NO(g)

Use the half-reaction method to balance each redox reaction occurring in acidic aqueous solution. (a) \(\mathrm{ClO}_{4}^{~-}(a q)+\mathrm{Cl}^{-}(a q) \longrightarrow \mathrm{ClO}_{3}^{~-}(a q)+\mathrm{Cl}_{2}(g)\) (b) \(\mathrm{MnO}_{4}^{~-}(a q)+\mathrm{Al}(s) \longrightarrow \mathrm{Mn}^{2+}(a q)+\mathrm{Al}^{3+}(a q) \) (c) \(\mathrm{Br}_{2}(a q)+\mathrm{Sn}(s) \longrightarrow \mathrm{Sn}^{2+}(a q)+\mathrm{Br}^{-}(a q)\) Equation Transcription: Text Transcription: ClO_4^-(aq)+Cl-(aq) rightarrow ClO_3-(aq)+Cl2(g) MnO_4^-(aq)+Al(s) rightarrow Mn^2+(aq)+Al^3+(aq) Br_2(aq)+Sn(s) rightarrow Sn^2+(aq)+Br^-(aq)

Use the half-reaction method to balance each redox reaction occurring in acidic aqueous solution. (a) \(\mathrm{IO}_{3}^{~-}(a q)+\mathrm{SO}_{2}(g) \longrightarrow \mathrm{I}_{2}(s)+\mathrm{SO}_{4}^{~2-}(a q)\) (b) \(\mathrm{Sn}^{4+}(a q)+\mathrm{H}_{2}(g) \longrightarrow \mathrm{Sn}^{2+}(a q)+\mathrm{H}^{+}(a q)\) (c) \(\mathrm{Cr}_{2} \mathrm{O}_{7}^{~2-}(a q)+\mathrm{Br}^{-}(a q) \longrightarrow \mathrm{Cr}^{3+}(a q)+\mathrm{Br}_{2}(a q)\) Equation Transcription: Text Transcription: IO_3-(aq)+SO_2(g) I_2(s)+SO_4^2-(aq) Sn^4+(aq)+H2(g) Sn^2+(aq)+H^+(aq) Cr_2O_7^2-(aq)+Br^-(aq) Cr^3+(aq)+Br_2(aq)

Balance each redox reaction occurring in basic solution. (a) \(\mathrm{ClO}^{-}(a q)+\mathrm{Cr}(\mathrm{OH})_{4}^{~-}(a q) \longrightarrow \mathrm{CrO}_{4}{ }^{2-}(a q)+\mathrm{Cl}^{-}(a q)\) (b) \(\mathrm{MnO}_{4}{ }^{-}(a q)+\mathrm{Br}^{-}(a q) \longrightarrow \mathrm{MnO}_{2}(s)+\mathrm{BrO}_{3}{ }^{-}(a q)\) Equation Transcription: Text Transcription: ClO^-(aq)+Cr(OH)_4^-(aq) CrO_4^2-(aq)+Cl^-(aq) MnO^-(aq)+Br^-(aq) MnO_2(s)+BrO_3^-(aq)

Balance each redox reaction occurring in basic solution. (a) \(\mathrm{NO}_{2}^{~-}(a q)+\mathrm{Al}(s) \longrightarrow \mathrm{NH}_{3}(g)+\mathrm{AlO}_{2}^{~-}(a q) \) (b) \(\mathrm{Al}(s)+\mathrm{MnO}_{4}^{~-}(a q) \longrightarrow \mathrm{MnO}_{2}(s)+\mathrm{Al}(\mathrm{OH})_{4}^{~-}(a q)\) Equation Transcription: Text Transcription: NO_2^-(aq)+Al(s) rightarrow NH_3(g)+AlO_2^-(aq) Al(s)+MnO_4^-(aq) rightarrow MnO_2(s)+Al(OH)_4^-(aq)

Which metal has the least tendency to be oxidized? (a) Ag (b) Na (c) Ni (d) Pb

Which metal is the best reducing agent? (a) Mn (b) Al (c) Ni (d) Cr

Which metal is the best reducing agent? (a) Ag (b) Mg (c) Fe (d) Pb

Determine whether each redox reaction occurs spontaneously in the forward direction. (a) \(\mathrm{Ca}^{2+}(a q)+\mathrm{Zn}(s) \longrightarrow \mathrm{Ca}(s)+\mathrm{Zn}^{2+}(a q)\) (b) \(2~ \mathrm{Ag}^{+}(a q)+\mathrm{Ni}(s) \longrightarrow 2~ \mathrm{Ag}(s)+\mathrm{Ni}^{2+}(a q)\) (c) \(\mathrm{Fe}(s)+\mathrm{Mn}^{2+}(a q) \longrightarrow \mathrm{Fe}^{2+}(a q)+\mathrm{Mn}(s)\) (d) \(2~ \mathrm{Al}(s)+3 \mathrm{~Pb}^{2+}(a q) \longrightarrow 2~ \mathrm{Al}^{3+}(a q)+3 \mathrm{~Pb}(s)\) Equation Transcription: Text Transcription: Ca^2+(aq)+Zn(s) rightarrow Ca(s)+Zn^2+(aq) 2 Ag^+(aq)+Ni(s) rightarrow 2 Ag(s)+Ni2+(aq) Fe(s)+Mn^2+(aq) rightarrow Fe^2+(aq)+Mn(s) 2 Al(s)+3 Pb^2+(aq) rightarrow 2 Al^3+(aq)+3 Pb(s)

Suppose you wanted to cause \(\mathrm{Ni^{2+}}\) ions to come out of solution as solid Ni. What metal could you use to accomplish this? Equation Transcription: Text Transcription: Ni^{2+}

Suppose you wanted to cause \(\mathrm{Pb^{2+}}\) ions to come out of solution as solid Pb. What metal could you use to accomplish this? Equation Transcription: Text Transcription: Pb^{2+}

Problem 81P Which metal in the activity series reduces Al3+ ions but not Na+ ions?

Problem 82P Which metal in the activity series is oxidized with a Ni2+ solution but not with a Cr3+ solution?

Problem 84P Which metals dissolve in HCl? For those metals that do dissolve, write a balanced redox reaction showing what happens when the metal dissolves. (a) Cr (b) Pb (c) Au (d) Zn

Problem 85P Make a sketch of an electrochemical cell with the overall reaction shown here. Label the anode, the cathode, and the salt bridge. Indicate the direction of electron flow. Hint: When drawing electrochemical cells, the anode is usually drawn on the left side. Mn(s) + Pb2+(aq) ? Mn2+(aq) + Pb(s)

Problem 86P Make a sketch of an electrochemical cell with the overall reaction shown here. Label the anode, the cathode, and the salt bridge. Indicate the direction of electron flow. Hint: When drawing electrochemical cells, the anode is usually drawn on the left side. Mg(s) + Ni2+(aq) ? Mg2+(aq) + Ni(s)

Problem 87P The following reaction occurs at the anode of an electrochemical cell: Zn(s) ? Zn2+ (aq) + 2e? Which cathode reaction would produce a battery with the highest voltage? (a) Mg2+(aq) + 2e? ? Mg(s) (b) Pb2+ (aq) + 2e? ? Pb(s) (c) Cr3+ (aq) + 3e? ? Cr(s) (a) Cu2+ (aq) + 2e? ? Cu(s)

Problem 88P The following reaction occurs at the cathode of an electrochemical cell: Ni2+(aq) + 2e? ? Ni(s) Which anode reaction would produce a battery with the highest voltage? (a) Ag(s) ? Ag+(aq) + e? (b) Mg(s) ? Mg2+(aq) + 2e? (c) Cr(s) ? Cr3+(aq) + 3e? (a) Cu(s) ? Cu2+(aq) + 2e?

Problem 89P Use half-cell reactions to determine the overall reaction that occurs in an alkaline battery.

Problem 94P Which metal, if coated onto iron, would prevent the corrosion of iron? (a) Mg (b) Cr (c) Cu

Problem 95P Determine whether each reaction is a redox reaction. For those reactions that are redox reactions, identify the substance being oxidized and the substance being reduced. (a) Zn(s) + CoCl2(aq) ? ZnCl2(aq) + Co(s) (b) HI(aq) + NaOH(aq) ? H2O(l) + NaI(aq) (c) AgNO3(aq) + NaCl(aq) ? AgCl(s) + NaNO3(aq) (a) 2 K(s) + Br2(l) ? 2 KBr(s)

Determine whether each reaction is a redox reaction. For those reactions that are redox reactions, identify the substance being oxidized and the substance being reduced. (a) \(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(a q)+2 \mathrm{LiCl}(a q) \longrightarrow\) (b) \(2 \mathrm{HBr}(a q)+\mathrm{Ca}(\mathrm{OH})_{2}(a q) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(l)+\mathrm{CaBr}_{2}(a q)\) (c) \(2 \mathrm{Al}(s)+\mathrm{Fe}_{2} \mathrm{O}_{3}(s) \longrightarrow \mathrm{Al}_{2} \mathrm{O}_{3}(s)+2 \mathrm{Fe}(l)\) (d) \(\mathrm{Na}_{2} \mathrm{O}(s)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow 2 \mathrm{NaOH}(a q)\)

Problem 99P If a strip of magnesium metal is dipped into a solution containing silver ions, does a spontaneous reaction occur? If so, write the two half-reactions and the balanced overall equation for the reaction.

Consider the unbalanced redox reaction. \(\mathrm{MnO}_4^{\ -}(aq)+\mathrm{Zn}(\mathrm{s})\longrightarrow\mathrm{Mn}^{2+}(aq)+\mathrm{Zn}^{2+}(aq)\) Balance the equation in acidic solution and determine how much of a \(0.500\mathrm{\ M}\mathrm{\ KMnO}_4\) solution is required to completely dissolve 2.85 g of Zn.

Problem 100P If a strip of tin metal is dipped into a solution containing zinc ions, does a spontaneous reaction occur? If so, write the two half-reactions and the balanced overall equation for the reaction.

A \(10.0-\mathrm{mL}\) sample of a commercial hydrogen peroxide \(\left(\mathrm{H}_{2} \mathrm{O}_{2}\right)\) solution is titrated with \(0.0998 \mathrm{M} \ \mathrm{KMnO}_{4}\). The end point is reached at a volume of \(34.81 \mathrm{~mL}\).Find the mass percent of \(\mathrm{H}_{2} \mathrm{O}_{2}\) in the commercial hydrogen peroxide solution. (Assume a density of \(1.00 \mathrm{~g} / \mathrm{mL}\) for the hydrogen peroxide solution.) The unbalanced redox reaction that occurs in acidic solution during the titration is: \(\mathrm{H}_{2} \mathrm{O}_{2}(a q)+\mathrm{MnO}_{4}^{-}(a q) \longrightarrow \mathrm{O}_{2}(g)+\mathrm{Mn}^{2+}(a q)\)

Silver is electroplated at the cathode of an electrolysis cell by this half-reaction. \(\mathrm{Ag}^{+}(a q)+\mathrm{e}^{-} \longrightarrow \mathrm{Ag}(s)\) How many moles of electrons are required to electroplate 5.8 g of Ag?

Problem 102P A 1.012-g sample of a salt containing Fe2+ is titrated with 0.1201 M KMnO4. The end point of the titration is reached at 22.45 mL. Find the mass percent of Fe2+ in the sample. The unbalanced redox reaction that occurs in acidic solution during the titration is: Fe2+(aq) + MnO4? (aq) ? Fe3+(aq) + Mn2+ (aq)

Problem 104P Gold is electroplated at the cathode of an electrolysis cell by this half-reaction. Au3+(aq) + 3e? ? Au(s) How many moles of electrons are required to electroplate 1.40 g of Au?

Problem 106P Determine whether HCl can dissolve each metal sample. If it can, write a balanced chemical reaction showing how the metal dissolves in HCl and determine the minimum amount of 6.0 M HCl required to completely dissolve the sample. (a) 5.90 g Ag (b) 2.55 g Pb (c) 4.83 g Sn (d) 1.25 g Mg

Problem 105P Determine whether HI can dissolve each metal sample. If it can, write a balanced chemical reaction showing how the metal dissolves in HI and determine the minimum amount of 3.5 M HI required to completely dissolve the sample. (a) 5.95 g Cr (b) 2.15 g Al (c) 4.85 g Cu (d) 2.42 g Au

Problem 107P One drop (assume 0.050 mL) of 6.0 M HCl is placed onto the surface of 0.028-mm-thick aluminum foil. What is the maximum diameter of the hole that will result from the HCl dissolving the aluminum? (Density of aluminum = 2.7 g/cm3)

Consider the molecular views of an Al strip and \(\mathrm{Cu}^{2+}\) solution. Draw a similar sketch showing what happens to the atoms and ions if the Al strip is submerged in the solution for a few minutes. Equation Transcription: Cu2+ Text Transcription: Cu^2+

A student prepares several samples of the same gas and measures their mass and volume. The results are tabulated as follows. Formulate a tentative law from the measurements.

Problem 55P Assign an oxidation state to each element in each compound. (a) Cu(NO3)2 (b) Sr(OH)2 (c) K2Cr2O7 (d) NaHCO3

Problem 56P Assign an oxidation state to each element in each compound (a) Na3PO4 (b) Hg2S (c) Fe(CN)3 (d) NH4Cl

What is the oxidation state of S in each ion? (a) \(\mathrm{SO}_4{ }^{2-}\) (b) \(\mathrm{SO}_3{ }^{2-}\) (c) \(\mathrm{HSO}_3{ }^{-}\) (d) \(\mathrm{HSO}_4^{-}\)

Problem 72P Which metal has the least tendency to be oxidized? (a) Sn (b) Mg (c) Cu (d) Fe

Which metal cation has the greatest tendency to be reduced? (a) \(\mathrm{Mn^{2+}}\) (b) \(\mathrm{Cu^{2+}}\) (c) \(\mathrm{K^+}\) (d) \(\mathrm{Ni^{2+}}\) Equation Transcription: Text Transcription: Mn^{2+} Cu^{2+} K^+ Ni^{2+}

Which metal cation has the greatest tendency to be reduced? (a) \(\mathrm{Pb^{2+}}\) (b) \(\mathrm{Cr^{3+}}\) (c) \(\mathrm{Fe^{2+}}\) (d) \(\mathrm{Sn^{2+}}\)

Problem 77P Determine whether each redox reaction occurs spontaneously in the forward direction. (a) Ni(s) + Zn2+(aq) ? Ni2+(aq) + Zn(s) (b) Ni(s) + Pb2+(aq) ? Ni2+(aq) + Pb(s) (c) Al(s) + 3 Ag+(aq) ? 3 Al3+ (aq) + Ag(s) (a) Pb(s) + Mn2+(aq) ? Pb2+(aq) + Mn(s)

Which metal cation has the greatest tendency to be reduced? (a) (b) (c) (d)

Use half-cell reactions to determine the overall reaction that occurs in a lead-acid storage battery.

Make a sketch of an electrolysis cell that could be used to electroplate nickel onto other metal surfaces. Label the anode and the cathode and show the reactions that occur at each.

Problem 98P Consider the unbalanced redox reaction. Cr2O72? (aq) + Cu(s) ? Cr3+(aq) + Cu2+(aq) Balance the equation in acidic solution and determine how much of a 0.850 M K2Cr2O7 solution is required to completely dissolve 5.25 g of Cu

Make a sketch of an electrolysis cell that could be used to electroplate nickel onto other metal surfaces. Label the anode and the cathode and show the reactions that occur at each.

The electrolytic cell represented in Figure \(16.17\) can be used to plate silver onto other metal surfaces. The plating reaction is: \(\mathrm{Ag}^{+}(a q)+\mathrm{e}^{-} \longrightarrow \operatorname{Ag}(s)\). Notice from the reaction that 1 mol \(e^{-}\) plates out 1 mol Ag(s). Use this stoichiometric relationship to determine how much time is required with an electrical current 0.100 amp to plate out 1.0 g Ag. The amp is a unit of electrical current equivalent to 1 C/s. (Hint: Recall that the charge of an electron is \(1.60 \times 10^{-19}\) C.)

An electrolytic cell similar to the one represented in Figure \(16.17\) can be used to plate gold onto other metal surfaces. The plating reaction is: \(\mathrm{Au}^{+}(a q)+\mathrm{e}^{-} \longrightarrow \mathrm{Au}(s)\). Notice from the reaction that 1 mol \(e^{-}\) plates out 1 mol Au(s). Use this stoichiometric relationship to determine how much time is required with an electrical current of 0.200 amp to plate out \(0.400 g Au\). The amp is a unit of electrical current equivalent to 1 C/s. (Hint: Recall that the charge of an electron is \(1.60 \times 10^{-19}\) C.)

Suppose a fuel-cell generator produces electricity for a house. If each \(\mathrm{H_2}\) molecule produces \(2 \mathrm e^-\), how many kilograms of hydrogen are required to generate the electricity needed for a typical house? Assume the home uses about 850 kWh of electricity per month, which corresponds to approximately \(2.65 \times 10^4\) mol of electrons at the voltage of a fuel cell.