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문제 1
In the Brønsted–Lowry concept of acids and bases, acid– base reactions are viewed as proton-transfer reactions. The stronger the acid, the weaker is its conjugate base. If we were to think of redox reactions in a similar way, what particle would be analogous to the proton? Would strong oxidizing agents be analogous to strong acids or strong bases? [Sections 20.1 and 20.2]
- Indicate whether the following balanced equations involve oxidation–reduction. If they do, identify the elements that undergo changes in oxidation number. (b) 2 PbO2(s) → 2 PbO(s) + O2(g) (c) 2 H2SO4(aq) + 2 NaBr(s) → Br2(l) + SO2(g) + Na2SO4(aq) + 2 H2O(l)
문제 2
문제 3a
The diagram that follows represents a molecular view of a process occurring at an electrode in a voltaic cell.
(a) Does the process represent oxidation or reduction?
문제 3b
The diagram that follows represents a molecular view of a process occurring at an electrode in a voltaic cell.
(b) Is the electrode the anode or cathode?
문제 3c
The diagram that follows represents a molecular view of a process occurring at an electrode in a voltaic cell.
(c) Why are the atoms in the electrode represented by larger spheres than those in the solution? [Section 20.3]
문제 4
Assume that you want to construct a voltaic cell that uses the following half-reactions: A2+1aq2 + 2 e- ¡ A1s2 Ered ° = -0.10 V B2+1aq2 + 2 e- ¡ B1s2 E°red = -1.10 V You begin with the incomplete cell pictured here in which the electrodes are immersed in water.
(a) What additions must you make to the cell for it to generate a standard emf?
- For a spontaneous reaction A1aq2 + B1aq2 → A-1aq2 + B+1aq2, answer the following questions: (a) If you made a voltaic cell out of this reaction, what half-reaction would be occurring at the cathode, and what half-reaction would be occurring at the anode?
문제 5
- The standard reduction potential for the reduction of RuO4^-(aq) to RuO4^2-(aq) is +0.59 V. By using Appendix E, which of the following substances can oxidize RuO4^2-(aq) to RuO4^-(aq) under standard conditions: Br2(l), BrO3^-(aq), Mn^2+(aq), O2(g), Sn^2+(aq)?
문제 5
문제 6
Consider the following table of standard electrode potentials for a series of hypothetical reactions in an aqueous solution: reduction half-reaction E °(V) (c) Which substance(s) can oxidize C2+?
- A voltaic cell is constructed with two silver–silver chloride electrodes, each of which is based on the following half-reaction: AgCl(s) + e- → Ag(s) + Cl-(aq). The two half-cells have [Cl-] = 0.0150 M and [Cl-] = 2.55 M, respectively. (c) What is the cell emf for the concentrations given? (d) For each electrode, predict whether [Cl-] will increase, decrease, or stay the same as the cell operates.
문제 7
문제 8c
Consider the following voltaic cell:
(c) What is the change in the cell voltage when the ion concentrations in the cathode half-cell are increased by a factor of 10?
- (a) What is an electrolytic cell? (b) The negative terminal of a voltage source is connected to an electrode of an electrolytic cell. Is the electrode the anode or the cathode of the cell? Explain.
문제 9
문제 10b
The electrodes in a silver oxide battery are silver oxide 1Ag2O2 and zinc (b) Which battery do you think has an energy density most similar to the silver oxide battery: a Li-ion battery, a nickel– cadmium battery, or a lead–acid battery? [Section 20.7]
문제 11
Bars of iron are put into each of the three beakers as shown here. In which beaker—A, B, or C—would you expect the iron to show the most corrosion ? [Section 20.8]
문제 12a
Magnesium, the element, is produced commercially by electrolysis from a molten salt (the 'electrolyte') using a cell similar to the one shown here. (a) What is the most common oxidation number for Mg when it is part of a salt?
문제 12b
Magnesium, the element, is produced commercially by electrolysis from a molten salt (the 'electrolyte') using a cell similar to the one shown here. (b) Chlorine gas is evolved as voltage is applied in the cell. Knowing this, identify the electrolyte.
문제 12c
Magnesium, the element, is produced commercially by electrolysis from a molten salt (the 'electrolyte') using a cell similar to the one shown here. (c) Recall that in an electrolytic cell the anode is given the + sign and the cathode is given the – sign, which is the opposite of what we see in batteries. What half-reaction occurs at the anode in this electrolytic cell?
- (a) What is meant by the term oxidation? (b) What is meant by the term oxidant? (c) What is meant by the term oxidizing agent?
문제 13
문제 13b
(b) On which side of an oxidation half-reaction do the electrons appear?
- (a) What is meant by the term reduction? (b) On which side of a reduction half-reaction do the electrons appear? (c) What is meant by the term reductant? (d) What is meant by the term reducing agent?
문제 14
문제 15a
Indicate whether each of the following statements is true or false: (a) If something is oxidized, it is formally losing electrons.
문제 15b
Indicate whether each of the following statements is true or false: (b) For the reaction Fe3+(aq) + Co2+(aq) → Fe2+(aq) + Co3+(aq), Fe3+(aq) is the reducing agent and Co2+(aq) is the oxidizing agent.
문제 15c
Indicate whether each of the following statements is true or false: (c) If there are no changes in the oxidation state of the reactants or products of a particular reaction, that reaction is not a redox reaction.
문제 16a,b
Indicate whether each of the following statements is true or false: (a) If something is reduced, it is formally losing electrons. (b) A reducing agent gets oxidized as it reacts.
문제 16c
Indicate whether each of the following statements is true or false: (c) An oxidizing agent is needed to convert CO into CO2.
문제 17
For each of the following balanced oxidation–reduction reactions, (i) identify the oxidation numbers for all the elements in the reactants and products and (ii) state the total number of electrons transferred in each reaction. (a) I2O5(s) + 5 CO(g) → I2(s) + 5 CO2(g) (b) 2 Hg2+(aq) + N2H4(aq) → 2 Hg(l) + N2(g) + 4 H+(aq) (c) 3 H2S(aq) + 2 H+(aq) + 2 NO3-(aq) → 3 S(s) + 2 NO(g) + 4 H2O(l)
문제 18
For each of the following balanced oxidation–reduction reactions, (i) identify the oxidation numbers for all the elements in the reactants and products and (ii) state the total number of electrons transferred in each reaction. (a) 2 MnO4-(aq) + 3 S2-(aq + 4 H2O(l) → 3 S(s) + 2 MnO2(s) + 8 OH-(aq) (b) 4 H2O2(aq) + Cl2O7(g) + 2 OH-(aq) → 2 ClO2-(aq) + 5 H2O(l) + 4 O2(g) (c) Ba2+(aq) + 2 OH-(aq) + H2O2(aq) + 2 ClO2(aq) → Ba(ClO2)2(s) + 2 H2O(l) + O2(g)
문제 19a
Indicate whether the following balanced equations involve oxidation–reduction. If they do, identify the elements that undergo changes in oxidation number. (a) PBr3(l) + 3 H2O(l) → H3PO3(aq) + 3 HBr(aq)
문제 19b,c
Indicate whether the following balanced equations involve oxidation–reduction. If they do, identify the elements that undergo changes in oxidation number. (b) NaI(aq) + 3 HOCl(aq) → NaIO3(aq) + 3 HCl(aq) (c) 3 SO(1g) + 2 HNO3(aq) + 2 H2O(l) → 3 H2SO4(aq) + 2 NO(g)
문제 20a
Indicate whether the following balanced equations involve oxidation–reduction. If they do, identify the elements that undergo changes in oxidation number. (a) 2 AgNO3(aq) + CoCl2(aq) → 2 AgCl(s) + Co(NO3)2(aq)