Practice Set Chapter 19 PDF

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Practice Set Chapter 19 Name___________________________________

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) What are the coefficients in front of NO 3 -(aq) and Cu(s ) when the following redox equation is balanced in an acidic solution:

1)

________ NO 3 -(aq) + ________ Cu(s ) → ________ NO(g) + ________ Cu2+(aq)? A) 3, 6

B) 3, 4

C) 2, 3

D) 2, 6

2) What is true when the following equation is balanced in basic solution?

2)

P(s ) + PO 43-(aq) → HPO 3 2-(aq) A) B) C) D)

H+ appears on the left side of the equation. OH- appears on the left side of the equation. OH- appears on the right side of the equation. H+ appears on the right side of the equation.

3) Determine the number of water molecules necessary to balance the following chemical equation.

3)

Cr2O 72-(aq) + Cl -(aq) + H+(aq) → Cr 3 +(aq) + Cl 2(g) + ________ H2O(l) A) 3

B) 7

C) 14

D) 5

4) What is the oxidation half reaction in the following chemical reaction?

4)

Cr2O 72-(aq) + 6 Cl-(aq) + 14 H+ (aq) → 2 Cr3+(aq) + 3 Cl2(aq) + 7 H2O(l) A) 2 Cl -(aq) → Cl 2(aq) + 2e B) Cr2O 72-(aq) + 14 H+(aq) + 6e - → 2 Cr3+(aq) + 7 H2O(l) C) Cl2(aq) + 2e - → 2 Cl-(aq) D) Cr2O 72-(aq) + 14 H+(aq) → 2 Cr3+(aq) + 7 H2O(l) + 6e 5) According to the balanced equation shown below, 1.00 mole of oxalic acid, H2C2O 4, reacts with ________ moles of permanganate ion, MnO 4-. 5 H2C2O 4(aq) + 2 MnO 4-(aq) + 6 H+(aq) → 10 CO 2(g) + 2 Mn2+(aq) + 8 H2O(l) A) 1.00

B) 2.25

C) 2.00

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D) 0.400

5)

6) Based on the balanced chemical equation shown below, what volume of 0.250 M K2S 2O 3(aq) is

6)

needed to completely react with 12.44 mL of 0.125 M KI3 (aq)? 2 S 2O 3 2-(aq) + I3 -(aq) → S 4O 6 2-(aq) + 3 I-(aq) A) 3.11 mL

B) 6.22 mL

C) 49.8 mL

D) 12.4 mL

7) Based on the balanced chemical equation shown below, determine the molarity of a solution containing Fe 2+(aq), if 40.00 mL of the Fe 2+(aq) solution is required to completely react with 30.00 mL of a 0.125 M potassium bromate, KBrO 3 (aq), solution.The chemical equation for the

7)

reaction is: 6 Fe 2+(aq) + BrO 3 -(aq) + 6 H+(aq) → 6 Fe 3+(aq) + Br -(aq) + 3 H2O(l). A) 0.562 M

B) 1.00 M

C) 0.0156 M

D) 0.0938 M

8) The iron content of foods can be determined by dissolving them in acid (forming Fe 3+), reducing the iron(III) to iron(II), and titrating with cerium(IV):

8)

Fe 2+(aq) + Ce 4+(aq) → Fe 3+(aq) + Ce 3+(aq). Identify the two half-reactions in the above reaction. A) oxidation half-reaction reduction half-reaction 3+ 2+ Ce 4+(aq) → Ce 3+(aq) + e Fe (aq) + e →? Fe (aq) B) oxidation half-reaction reduction half-reaction Fe 2+(aq) → Fe 3 +(aq) + e Ce 4+(aq) + e - → Ce 3 + (aq) C) oxidation half-reaction reduction half-reaction 3 + 2+ Ce 4+(aq) + e - → Ce 3+(aq) Fe (aq) → Fe (aq) + e D) oxidation half-reaction reduction half-reaction Fe 2+ (aq) + e - → Fe 3+(aq) Ce 4+(aq) → Ce 3+(aq) + e 9) Which of the following terms can be used to describe an electrochemical cell in which a spontaneous chemical reaction generates an electric current?

9)

I. an electrolytic cell II. a galvanic cell III. a voltaic cell A) only I

B) only II

C) only III

D) II and III

10) During an electrochemical reaction, electrons move through the external circuit toward the ________ and positive ions in the cell move toward the ________. A) cathode, cathode B) cathode, anode C) anode, anode D) anode, cathode

2

10)

11) In a galvanic cell, the half-reaction MnO 4-(aq) + 8 H+(aq) + 5 e - → Mn 2+(aq) + 4 H2O(l) is A) a reduction half-reaction and occurs at the anode. B) an oxidation half-reaction and occurs at the cathode. C) an oxidation half-reaction and occurs at the anode. D) a reduction half-reaction and occurs at the cathode.

11)

12) What species is oxidized in the reaction: CuSO 4(aq) + Mg(s ) → MgSO 4(aq) + Cu(s )? A) Mg (s ) B) Cu (s ) C) CuSO 4 (aq) D) MgSO 4 (aq)

12)

13) For a galvanic cell that uses the following two half-reactions,

13)

Cr2O 72-(aq) + 14 H+(aq) + 6 e - → 2 Cr3+(aq) + 7 H2O(l) Pb(s ) → Pb 2+(aq) + 2 e how many moles of Pb(s) are oxidized by one mole of Cr2O 72-? A) 6

B) 3

C) 1

3

D) 2

Consider the galvanic cell shown below.

14) Identify the anode and cathode, and indicate the direction of ion flow to and from each electrode. A) Co is the anode and Al is the cathode; Al3+ ions flow to the cathode and Co2+ ions flow from the anode. B) Co is the anode and Al is the cathode; Co 2+ ions flow to the anode and Al3+ ions flow from the cathode. C) Al is the anode and Co is the cathode; Co 2+ ions flow to the cathode and Al3+ ions flow from the anode. D) Al is the anode and Co is the cathode; Al3+ ions flow to the anode and Co 2+ ions flow

14)

from the cathode. 15) What is the balanced equation for the cell reaction? A) 2 Al3+(aq) + 3 Co 2+(aq) → 2 Al(s ) + 3 Co(s ) B) 2 Al(s ) + 3 Co(s ) → 2 Al3+(aq) + 3 Co 2+(aq) C) 2 Al(s ) + 3 Co 2+(aq) → 2 Al 3+(aq) + 3 Co(s ) D) 2 Al3+(aq) + 3 Co(s ) → 2 Al(s ) + 3 Co 2+(aq)

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15)

Shown below is a galvanic cell with anode compartment b containing anode a and cathode compartment d containing cathode c. Electrons flow through wire f, ions flow through salt bridge e, and the cell potential is read using voltmeter g. This galvanic cell uses the reaction: Cu(s ) + 2 Ag+(aq) → 2 Ag(s ) + Cu2+(aq).

16) Identify the electrodes and the direction of electron flow. A) a is Ag, c is Cu and electrons flow from c to a B) a is Ag, c is Cu and electrons flow from a to c C) a is Cu, c is Ag and electrons flow from a to c D) a is Cu, c is Ag and electrons flow from c to a

16)

17) What is the balanced equation for the galvanic cell reaction expressed using shorthand notation below?

17)

Mg(s ) ∣ Mg2+(aq) ∣∣ Cl 2(g) ∣ Cl -(aq) ∣ C(s ) A) Mg(s ) + Cl 2(g) → Mg2+(aq) + 2 Cl-(aq)

B) Mg(s ) + 2 Cl-(aq) → Mg2+(aq) + Cl 2(g)

C) Mg2+(aq) + 2 Cl-(aq) → Mg(s ) + Cl 2(g)

D) Mg2+(aq) + 2 Cl-(aq) → MgCl 2(s )

18) The cell reaction for a dry cell battery is

18)

Zn(s ) + 2 MnO 2(s ) + 2 NH4+(aq) → 2 NH3 (aq) + Mn2O 3 (s ) + Zn2+(aq) + H2O(l). The standard cell potential for this cell is 1.56 V. What is the standard free energy change for this cell? A) -602 kJ B) +151 kJ C) -301 kJ D) -151 kJ 19) Doubling all the coefficients in the equation for the cell reaction B) doubles ∆G°, but does not change E°. A) doubles E°, but does not change ∆G°. C) doubles both E° and ∆G°. D) does not change E° or ∆G°.

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19)

20) For the hypothetical reaction A + Bx → Ax + B, E° = 1.19 V = and ∆G° = -115 kJ. For this reaction the value of x = ________. A) 1 B) 2 C) 3 D) 4

20)

21) Which is not true for standard electrode potentials? A) E° for oxidation is the negative of E° for reduction. B) The potential for the standard hydrogen electrode is chosen to be +1.00 V. C) Cell constituents are in their standard states. D) The half-reactions are written as reductions.

21)

22) Given the half-cell potentials below, calculate the cell potential.

22)

Ag+(aq) + e - → Ag(s ) Cu2+(aq) + 2 e - → Cu(s ) A) 1.14 V

0.80 V 0.34 V B) 0.46 V

C) 1.94 V

D) 1.26 V

23) A galvanic cell consists of a La3+/La half-cell and a standard hydrogen electrode. If the La3+ /La half-cell standard cell functions as the anode, and the standard cell potential is 2.52 V, what is the standard reduction potential for the La3+/La half-cell? A) +0.84 V B) -2.52 V C) +2.52 V D) -0.84 V

23)

24) Consider the following standard reduction potentials,

24)

Al 3+(aq) + 3 e - → Al(s ) I2(s ) + 2 e - → 2 I-(aq)

E° = -1.66 V E° = +0.54 V

Under standard conditions, A) I-(aq) is a stronger oxidizing agent than Al(s ), and I2(s ) is a stronger reducing agent than Al 3+(aq). B) Al(s ) is a stronger oxidizing agent than I-(aq), and Al 3+(aq) is a stronger reducing agent than I2(s ). C) I2(s ) is a stronger oxidizing agent than Al3+(aq), and Al(s ) is a stronger reducing agent than I-(aq). D) Al 3+(aq) is a stronger oxidizing agent than I2(s ), and I-(aq) is a stronger reducing agent than Al(s ).

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25) Using the following standard reduction potentials Fe 3 +(aq) + e - → Fe 2+(aq) Pb2+(aq) + 2 e - → Pb(s )

25)

E° = +0.77 V E° = -0.13 V

calculate the standard cell potential for the galvanic cell reaction given below, and determine whether or not this reaction is spontaneous under standard conditions. Pb2+(aq) + 2 Fe 2+(aq) → 2 Fe 3+(aq) + Pb(s ) A) E° = +0.90 V, nonspontaneous C) E° = -0.90 V, nonspontaneous

B) E° = +0.90 V, spontaneous D) E° = -0.90 V, spontaneous

26) Based on the half-reactions and their respective standard reduction potentials below, which addition to an aqueous solution containing Fe(NO 3 ) 2 will result in a reaction under standard-state conditions? O 2(g) + 4 H+ +4 e - → 2 H2O(l) Fe 3 +(aq) + e - → Fe 2+(aq)

1.23 V

Cu2+(aq) + 2 e - → Cu(s ) 2 H+(aq) + 2 e - → H2(g)

0.34 V 0.00 V

Ni2+(aq) + + 2 e - → Ni(s ) Fe 2+(aq) + 2 e - → Fe(s )

-0.26 V

0.77 V

-0.45 V

A) nickel wire C) aqueous copper(II) acetate

B) oxygen gas D) hydrogen gas

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26)

27) According to Table 19.1, which aqueous metal ion will reduce Ag+, but not Cu2+? A) Mn2+ B) Sn2+ C) Fe 3 + D) Fe 2+

27)

28) When suspected drunk drivers are tested with a Breathalyzer, the alcohol (ethanol) in the exhaled breath is oxidized to acetic acid with an acidic solution of potassium dichromate:

28)

3CH3 CH2OH(aq) + 2Cr 2O 7-2 (aq) + 16H+ (aq)

3CH3 CO 2H(aq) + 4Cr +3 (aq) + 11H2O (l)

If Eº for this cell is 1.30V and the standard half-cell potential of Cr 2O 7-2(aq) to Cr+3 is 1.358 V, what is the standard half-cell reduction potential for the conversion of acetic acid to ethanol? A) -2.658 V B) -0.058 V C) + 0.058 V D) 2.658 V

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29)

29) Table 19.1 lists out Standard Reduction Potentials at 25°C. Two of them are: Cl2(g) + 2e - → 2 Cl-(aq) Sn4+(aq) + 2 e - → Sn 2+(aq)

E° = +1.36 V E° = 0.15 V

calculate the standard cell potential for the following reaction: Sn4+(aq) + 2 Cl-(aq) → Sn 2+(aq) + Cl 2(g) A) E° = 1.51 V

B) E° = 1.21 V

C) E° = -1.51 V

D) E° = -1.21 V

30) Consider the galvanic cell, Pb(s ) ∣ Pb 2+(aq) ∣∣ Cu 2+(aq) ∣ Cu(s ). Which one of the following changes to the cell would cause the cell potential to increase (i.e., become more positive)? A) decrease the mass of Pb(s ) B) increase the [Pb2+] concentration C) increase the mass of Pb(s ) D) increase the [Cu2+] concentration

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30)

31) Calculate the cell potential at 25°C for the cell

31)

Fe(s ) ∣ (Fe 2+(0.100 M) ∣∣ Pd2+ (1.0 × 10 -5 M) ∣ Pd(s ) given that the standard reduction potential for Fe 2+/Fe is -0.45 V and for Pd2+/Pd is +0.95 V. A) +1.52 V B) +1.68 V C) +1.16 V D) +1.28 V 32) Given that E° = +0.897 V, calculate E at 25°C for

32)

Pb(s ) ∣ Pb 2+(0.0400 M) ∣∣ Fe 3+(0.200 M), Fe 2+(0.0100 M) ∣ Pt(s ) A) +0.935 V

B) +1.015 V

C) +0.779 V

D) +1.134 V

33) How many moles of electrons, n, are transferred in the following reduction-oxidation reaction?

33)

2 MnO 4-(aq) + 16 H+(aq) + 10 Cl-(aq) → 2 Mn2+(aq) + 5 Cl2(g) + 8 H2O(l) A) 4

B) 5

C) 10

D) 2

34) Which is most often used in the laboratory to measure pH? A) a conductivity cell B) a Daniell cell C) a standard hydrogen electrode D) a glass electrode

34)

35) The following cell has a potential of 0.45 V at 25°C.

35)

Pt(s ) ∣ H2(1 atm)|H+ (? M) ∣∣ Cl -(1 M) ∣ Hg2Cl2(s )|Hg(l) The standard half-cell potential for the half-reaction Hg2Cl2(s ) + 2 e - → 2 Hg(l) + 2 Cl-(aq) is 0.28 V. What is the pH in the anode compartment? A) 2.9 B) 7.6

C) 12.3

D) 4.7

36) How many grams of nickel metal are plated out when a constant current of 15.0 A is passed through aqueous NiCl2 for 80.0 minutes? A) 48.4 g

B) 21.9 g

C) 14.7 g

D) 43.8 g

37) How long must a constant current of 50.0 A be passed through an electrolytic cell containing aqueous Cu2+ ions to produce 3.00 moles of copper metal? A) 1.61 hours

B) 3.22 hours

C) 0.311 hours

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36)

D) 0.621 hours

37)...