Chapter 17 - Practice Multiple Choice Test 1 (from Kotz 5^th Edition Chapter 21)
1. Which of the following changes requires a reducing agent?
			a.		Cr2O7^2- --> CrO4^2-
			b.		ClO4^- --> ClO3^-
			c.		NH3 --> NH4^+
			d.		Al --> Al^3+
			e.		O^2- --> O2^2-
2. In the following oxidation-reduction reaction 8H^+(aq) + 6Cl^-(aq) + Sn(s) + 4NO3^-(aq) --> SnCl6^2-(aq) + 4NO2(g) + 4H2O the oxidizing agent is
			a.		H^+.
			b.		Cl^-.
			c.		Sn.
			d.		NO3^-.
			e.		SnCl6^2-.
	3. For the reaction: 4FeCr2O4 + 8Na2CO3 + 7O2 + 4H2SO4 --> 4Na2Cr2O7 + 2Fe2O3 + 4H2O + 8CO2 + 4Na2SO4 the oxidizing agent is _______ and the element(s) oxidized is (are) _______.
		a.		O2; Na2CO3
		b.		Na2CO3; O
		c.		O2; Fe and Cr
		d.		O2; CO2
		e.		O2; Cr, C

4. A sulfur-containing species that cannot be reduced is
	a.	H2SO3.
	b.	SO4^2-.
	c.	S2O3^2-.
	d.	SO3^2-.
	e.	S^2-.
5. In which of the following half reactions is reduction occurring?
	a.	SO3 --> SO4^2-
	b.	SO2 --> HSO3^-
	c.	H2O2 --> OH^-
	d.	Mn^2+ --> Mn2O3
	e.	CrO4^2- --> Cr2O7^2-

6. In the redox reaction 2Fe^3+ + 2Br^- --> Br2 + 2Fe^2+, which of the following are the correct half reactions? 1. 2Br^- --> Br2 + 2e 2. Br^- --> Br + e 3. 2Br^- + 2e --> Br2 4. Fe^3+ + e --> Fe^2+ 5. Fe^3+ --> Fe^2+ + e
	a.	1 and 4
	b.	2 and 5
	c.	2 and 4
	d.	3 and 4
	e.	3 and 5

7. For the oxidation of ethanol to ethanoic acid (acetic acid) C2H5OH --> CH3COOH (not balanced) the number of electrons that must be added to the right side is
	a.	zero.
	b.	one.
	c.	two.
	d.	three.
	e.	four.

8. When the half-reaction involving the conversion of ClO^- to ClO3^- in basic solution is balanced, there are
	a.	4 OH^- + 4e on the left-hand side.
	b.	4 OH^- on the left side and 4 electrons on the right.
	c.	2 OH^- on the left side and 2 electrons on the right.
	d.	2 OH^- on the left side and 2 electrons on the left.
	e.	1 OH^- on the left side and 2 electrons on the right.

9. The following reaction occurs in basic solution: ___ H2O + ___ MnO4^- + ___ ClO2^- --> ___ MnO2 + ___ ClO4^- + ___ OH^- Balance the equation above and then add together all of the coefficients in the balanced equation. The sum of these coefficients is
	a.	15.
	b.	20.
	c.	24.
	d.	25.
	e.	30.

10. In a voltaic cell, the electron flow is always from
	a.	the positive electrode to the negative electrode.
	b.	through the salt bridge.
	c.	from the oxidizing agent through the salt bridge to the reducing agent.
	d.	from the reducing agent through the salt bridge to the oxidizing agent.
	e.	from the anode to the cathode.
11. Calculate the Gibbs free energy change for the reaction below when the initial concentrations of Cr^3+ and Cu^2+ are 1.00 M and the cell potential is 1.08 volts.
	a.	-1450 kJ
	b.	-625 kJ
	c.	-232 kJ
	d.	-208 kJ
	e.	+208 kJ

12. Iron reacts with hydrochloric acid to produce hydrogen and iron(II) ions, but copper does not react with hydrochloric acid to produce hydrogen. From this information we can predict that the following reaction would be spontaneous.
	a.	Cu + Fe^2+ --> Fe + Cu^2+
	b.	2Fe^2+ + Cu^2+ --> 2Fe^3+ + Cu
	c.	Fe + Cu^2+ --> Fe^2+ + Cu
	d.	2Cu^+ --> Cu + Cu^2+
	e.	Fe^2+ + Cu^2+ --> Fe^3+ + Cu^+
13. If the value of -0.50 V were assigned to the standard hydrogen half-cell instead of the currently accepted value of zero, the cell potential of a given electrochemical cell would
	a.	increase by 0.50 V.
	b.	decrease by 0.50 V.
	c.	increase by 1.0 V.
	d.	decrease by 1.0 V.
	e.	remain unchanged.

14. Given the standard reduction potentials

Cr^3+ + 3e --> Cr	-0.74 volts
Pb^2+ + 2e --> Pb	-0.13 volts

What is the standard cell potential, E^o, for the reaction
2Cr + 3Pb²⁺ --> 2Cr³⁺ + 3Pb

a.

-0.87 volts

b.

1.09 volts

c.

0.61 volts

d.

-1.87 volts

e.

none of these

15. The strongest reducing agent of this series is
	a.	Mn^2+.
	b.	Br2.
	c.	Br^-.
	d.	Sn.
	e.	Mn.

16. The element or ion that will oxidize mercury but will not oxidize bromide is
	a.	Mn.
	b.	Cu^+.
	c.	Mn^2+.
	d.	Ag.
	e.	Cu.

17. If all of the species below are in their standard states, which is the strongest oxidizing agent?
	a.	H^+
	b.	K
	c.	F^-
	d.	Al^3+
	e.	Pb^2+

18. Given the following standard electrode potentials: If the concentrations of ions are all 1.00 M and an electrochemical cell is constructed from Al, Al^3+, Tl^+, and Tl, which of the following statements is incorrect?
	a.	Electrons will flow from Tl through the external circuit to Al.
	b.	If the standard hydrogen half-cell were substituted for the Tl half-cell, the voltage would be 1.66 V.
	c.	The cell voltage would be 1.32 V.
	d.	The negative terminal of the voltmeter should be attached to Al for a positive reading.
	e.	The following electrode reaction will occur spontaneously: Tl^+(aq) + e --> Tl

19. For cell reaction 3Hg + Cr2O7^2- + 14H^+ --> 2Cr^3+ + 3Hg^2+ + 7H2O, the standard cell potential is 0.48 V. To determine the cell potential at nonstandard conditions, the value that should be used for n in the Nernst equation is
	a.	1
	b.	2
	c.	3
	d.	4
	e.	6

20. For cell reaction 3Hg + Cr2O7^2- + 14H^+ --> 2Cr^3+ + 3Hg^2+ + 7H2O, the standard cell potential is 0.48 V. Which change(s) will result in an increase in the cell potential? 1. Increasing the dichromate ion concentration 2. Increasing the pH 3. Increasing the mercury ion concentration 4. Increasing the amount of mercury
	a.	1 only
	b.	2 only
	c.	3 only
	d.	1 and 4 only
	e.	2 and 4 only
21. For a cell consisting of Zn, Zn^2+, Ag^+, and Ag, the standard cell potential is 1.56 V. A cell using these reagents was made and the observed potential was 1.35 V. A possible explanation for the observed voltage is
	a.	there was 0.0100 mole of Zn^2+ and 0.200 mole of Ag^+.
	b.	the [Zn^2+] was larger than [Ag^+].
	c.	the Ag electrode was twice as large as the Zn electrode.
	d.	the volume of the Zn^2+ solution was larger than the volume of the Ag^+ solution.
	e.	the volume of the Ag^+ solution was larger than the volume of the Zn^2+ solution.

22. A current of 10 amperes is passed through molten magnesium chloride for 3.0 hours. How many moles of magnesium metal could be produced by this electrolysis (one Faraday = 96,500 coulombs)?
	a.	1.1
	b.	2.2
	c.	0.56
	d.	0.37
	e.	0.22

23. When a sodium chloride solution is electrolyzed using platinum electrodes
	a.	Cl2 is produced at the anode.
	b.	O2 is produced at the anode.
	c.	O2 is produced at the cathode.
	d.	H2 is produced at the anode.
	e.	Na is produced at the cathode.

24. Protection of iron from corrosion can be accomplished by making an electrical contact between iron and certain other metals. Metal(s) that would provide protection is (are) 1. Hg. 2. Sn. 3. Al. 4. Ag.
	a.	1 only
	b.	3 only
	c.	1 and 2 only
	d.	2 and 4 only
	e.	3 and 4 only

25. A piece of iron half immersed in a sodium chloride solution will corrode more rapidly than a piece of iron half immersed in pure water because
	a.	the sodium ions oxidize the iron atoms.
	b.	the chloride ions oxidize the iron atoms.
	c.	the chloride ions form a precipitate with iron.
	d.	the chloride ions increase the pH of the solution.
	e.	the sodium ions and chloride ions carry a current through the solution.