Chapter 17 - Practice Multiple Choice Test 2 (from Kotz 5^th Edition Chapter 21) Electrochemistry
1. Which of the following changes requires an oxidizing agent?
		a.	NH3 --> NH4^+
		b.	N2H4 --> N2
		c.	NO3^- --> N2O
		d.	NO2^- --> N2O3
		e.	NO2 --> N2O4

2. In the balanced equation 2MnO4^- + 5C2O4^2- + 16H^+ --> 2Mn^2+ + 10 CO2 + 8H2O the reducing agent is
	a.	MnO4^-.
	b.	C2O4^2-.
	c.	H^+.
	d.	Mn^2+.
	e.	CO2.
3. For the reaction: 4FeCr2O4 + 8Na2CO3 + 7O2 + 4H2SO4 --> 4Na2Cr2O7 + 2Fe2O3 + 4H2O + 8CO2 + 4Na2SO4 The reducing agent is ______ and the oxidation product(s) is (are) ______.
		a.	Na2CO3; CO2 and Na2Cr2O7
		b.	FeCr2O4; Fe2O3 and Na2Cr2O7
		c.	FeCr2O4; Fe2O3 and H2O
		d.	FeCr2O4; Fe2O3, Na2Cr2O7 and H2O
		e.	Na2CO3; CO2 and H2O

4. In which of the following species does the underlined element have an oxidation number of +2?
	a.	Zn(OH)4^2-
	b.	CrO2Cl2
	c.	HNO2
	d.	PH4^+
	e.	NO2

5. All of the following half-reactions are balanced EXCEPT
	a.	2H2O + 2e --> H2 + 2OH^-
	b.	NO3^- + 4H^+ + 3e --> NO + 2H2O
	c.	2Ta + 5H2O --> Ta2O5 + 10H^+ + 10e
	d.	H3PO3 + H2O --> H3PO4 + 2H^+ + 2e
	e.	Fe^3+ --> Fe^2+ + e
6. I2 + 6H2O --> 2IO3^- + 12H^+ + ______ e How many electrons are needed to balance the half-reaction above?
	a.		2
	b.		6
	c.		8
	d.		10
	e.		12

7. Glycidol can be oxidized in acid solution to malonic acid. When the half-reaction C3H6O2 --> C3H4O4 is balanced, there are
	a.	2H^+ + 2e on the left-hand side.
	b.	2H^+ + 4e on the right-hand side.
	c.	4H^+ + 4e on the right-hand side.
	d.	4H^+ + 4e on the left-hand side.
	e.	6H^+ + 6e on the right-hand side.
8. Balance the equation below. Choose from the numbers given as answers the one that is the coefficient of the underlined substance in the balanced ionic reaction: Zn + NO3^- --> Zn(OH)4^2- + NH3 (basic solution)
	a.	1
	b.	2
	c.	4
	d.	6
	e.	8

9. For the reaction between permanganate ion and sulfite ion in basic solution, the unbalanced equation is MnO4^- + SO3^2- --> MnO2 + SO4^2-. When this equation is balanced using the smallest whole number coefficients possible, the number of OH^- ions is
	a.	two on the right.
	b.	two on the left.
	c.	three on the right.
	d.	four on the right.
	e.	four on the left.

10. Which of the following processes could occur at the anode of an electrochemical cell?
	a.	Cu^2+ + 2e --> Cu
	b.	Zn^2+ + 2e --> Zn
	c.	Cu --> Cu^2+ + 2e
	d.	Zn --> Zn^2+ + 2e
	e.	both c and d
11. Calculate the standard Gibbs free energy change for the reaction: 2Fe + 3Cl2 --> 2Fe^3+ + 6Cl^- given the following electrode potentials:
	a.	765 kJ
	b.	-269 kJ
	c.	-404 kJ
	d.	-765 kJ
	e.	-807 kJ

12. A cell with a potential of 0.15 V has the cell reaction 2Cu^2+(aq) + H2 --> 2Cu^+(aq) + 2H^+(aq) If the concentrations of ions were 1.0 molar and the pressure of H2 were 1.0 atmosphere, then E° for the half reaction Cu^2+(aq) + e --> Cu^+(aq) would be
	a.	-0.075 V.
	b.	-0.15 V.
	c.	0.075 V.
	d.	0.15 V.
	e.	0.30 V.

13. If the value of -1.00 volts was assigned to the standard hydrogen half-cell instead of the currently accepted value of zero 2H^+(aq) + 2e --> H2 E? = -1.00 V then all reduction half-cell potentials and all cell potentials would respectively
	a.	decrease by 1.00 V and decrease by 1.00 V.
	b.	decrease by 1.00 V and remain unchanged.
	c.	decrease by 1.00 V and increase by 1.00 V.
	d.	increase by 1.00 V and increase by 1.00 V.
	e.	increase by 1.00 V and decrease by 1.00 V.

14. Given the standard reduction potentials

Cr^3+ + 3e --> Cr	-0.74 V
Cu^2+ + 2e --> Cu	+0.34 V

what is the standard cell potential for the reaction
2Cr + 3Cu²⁺ --> 3Cu + 2Cr³⁺?

a.

-1.08 V

b.

-0.40 V

c.

0.40 V

d.

1.08 V

e.

2.50 V

. 15. An element or ion that will oxidize iron but will not oxidize mercury is
	a.	Al^3+.
	b.	Sn^2+.
	c.	Br^-.
	d.	Cu.
	e.	Al.
16. The strongest reducing agent of this series is
	a.	H2.
	b.	Br2.
	c.	Br^-.
	d.	Al.
	e.	Al^3+.

17. An element that would dissolve in HNO3 without the evolution of H2 would be
	a.	Fe.
	b.	Sn.
	c.	Cu.
	d.	Al.
18. The voltage produced in the reaction Fe + Cu^2+(aq) --> Cu + Fe^2+(aq) is independent of
	a.	the metal used as the anode.
	b.	the concentration of Fe^2+.
	c.	the concentration of Cu^2+.
	d.	the temperature.
	e.	the size of the anode.

19. From a consideration of the Nernst equation when the concentration of the reactants and products are all 1.0 molar then
	a.	E = 1.0.
	b.	E = E°.
	c.	E = 0.
	d.	E° = 0.
	e.	Kc = Q.

20. For a certain oxidation-reduction reaction, E° is negative. This means that
	a.	DG° is negative and K is less than 1.
	b.	DG° is negative and K is greater than 1.
	c.	DG° is zero and K is greater than 1.
	d.	DG° is positive and K is greater than 1.
	e.	DG° is positive and K is less than 1.
21. A cell consists of a magnesium electrode immersed in a solution of magnesium chloride and a silver electrode immersed in a solution of silver nitrate. The two half-cells are connected by means of a salt bridge. It is possible to increase the voltage of the cell by
			a.	addition of sodium chloride to both half-cells.
			b.	increasing the Mg^2+ concentration and decreasing the Ag^+ concentration.
			c.	increasing the size of the Mg electrode and decreasing the size of the Ag electrode.
			d.	decreasing the size of the Mg electrode and increasing the size of the Ag electrode.
			e.	decreasing the Mg^2+ concentration.
22. A copper electrode in CuSO4 solution is connected by a wire to a silver electrode in a AgNO3 solution. The two solutions are also joined by a salt bridge Current is allowed to flow through the cell until the mass of the silver electrode has changed by 108 g. During this time the mass of the copper electrode will
	a.	decrease by 108 g.
	b.	increase by 108 g.
	c.	increase by 31.8 g.
	d.	decrease by 31.8 g.
	e.	decrease by 63.5 g.

23. A steady current of 10.0 amp flowing for 965 sec. corresponds to
	a.	9650 electrons.
	b.	0.100 Faraday.
	c.	0.100 volt.
	d.	0.100 coulomb.
	e.	None of these.

24. When a dilute aqueous solution of Li2SO4 is electrolyzed, the products formed at the anode and cathode, respectively, are
	a.	O2 and H2.
	b.	H2 and O2.
	c.	O2 and H^+.
	d.	H2 and OH^-.
	e.	O2 and Li.
25. The following reaction takes place in a lead storage battery. PbO2(s) + Pb(s) + 2H2SO4(aq) --> 2PbSO4(s) + 2H2O(l) Which state is true?
	a.	The concentration of H2SO4 increases as the battery discharges.
	b.	Pb is formed at the anode during discharging.
	c.	PbO2 is formed at the anode during charging.
	d.	The mass of Pb decreases during charging.
	e.	The mass of PbSO4 remains constant during charging and discharging.