Chemistry Problems

Want to verify answers for exam review.

Question 1
Consider an electrochemical cell constructed from the following half cells, linked by an external circuit and by a KCl salt bridge:

an Al(s) electrode in 1.0 M Al(NO3)3 solution
a Pb(s) electrode in 1.0 M Pb(NO3)2 solution

What is the balanced overall (net) cell reaction?

Pb(s) + Al3+(aq) Pb2+(aq) + Al(s)
3Pb(s) + 2Al3+(aq) 3Pb2+(aq) + 2Al(s)
3Pb2+(aq) + 2Al(s) 3Pb(s) + 2Al3+(aq)
Pb2+(aq) + Al(s) Pb(s) + Al3+(aq)

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Question 2
Calculate the value of Eocell for the following reaction:

2Au(s) + 3Ca2+(aq) 2Au3+(aq) + 3Ca(s)

-4.37 V
-1.37 V
-11.6 V
1.37 V
4.37 V

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Question 3
An electrochemical cell based on the following reaction has a standard cell voltage (Eocell) of 0.48 V.

Sn(s) + Cu2+(aq) Sn2+(aq) + Cu(s)

What is the standard reduction potential of tin?

Sn2+(aq) + 2e- Sn(s)

-0.14 V
0.14 V
-0.82 V
0.82 V
None of the above

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Question 4
Which chemical species undergoes reduction according to the following cell diagram?

Sn | Sn2+ || NO3- (acid soln), NO(g) | Pt

Sn
Sn2+
NO3-
NO
Pt

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Question 5
In the following half equation, which is the oxidizing agent?

NO3-(aq) + 4H+(aq) + 3e- NO(g) + 2H2O

NO3-
H+
e-
NO
H2O

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Question 6
Which statement is true in regard to a spontaneous redox reaction?

Eored is always negative.
Eocell is always positive.
Eoox is always positive.
Eored is always positive.

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Question 7
Which of the following species is the strongest oxidizing agent under standard state conditions?

Ag+(aq)
H2(g)
H+(aq)
Cl2(g)
Al3+(aq)

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Question 8
Calculate the cell emf for the following reaction:

2Ag+(0.010 M) + H2(1 atm) 2Ag(s) + 2H+ (pH = 10.0)

1.04 V
1.27 V
0.92 V
0.56 V
0.80 V

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Question 9
A current of 2.50 A was passed through an electrolytic cell containing molten CaCl2 for 4.50 hours. How many moles of calcium metal should be deposited?

5.83 x 10-5 mol
0.210 mol
0.420 mol
0.840 mol
1.95 x 109 mol

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Question 10
How long will it take to produce 78 g of Al metal by the reduction of Al3+ in an electrolytic cell with a current of 2.0 A?

0.01 s
420 s
13 h
116 h
1.0 x 1012 s

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Question 11
According to the band theory, which of the following provide(s) an explanation for the high electrical conductivity of metals?

a partly filled conduction band
a valence band overlapping an empty conduction band
a filled valence band
a large gap between the valence band and the conduction band
1 and 2
1 and 3
3
3 and 4
4

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Question 12
Which one of the following elements would form p-type semiconductors when added to silicon crystals?

C
P
As
Ga
Mg

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Question 13
The electron configuration of an Fe2+ ion is ________.

[Ar]4s24d4
[Ar]4s23d6
[Ar]3d3
[Ar]3d5
[Ar]3d6

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Question 14
How many 3d electrons does a Mn2+ ion have?

1
2
3
4
5

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Question 15
In the complex ion [Fe(CN)6]4-, the oxidation number of Fe is ________.

+1
+2
+3
-4
+6

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Question 16
In the complex ion [Co(en)2Br2]+, the oxidation number of Co is ________.

+1
+2
+3
-2
-1

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Question 17
A bidentate ligand always ________.

has bonds formed to two metal ions
has a charge of 2+ or 2-
forms complex ions with a charge of 2+ or 2-
has two donor atoms
has medical uses

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Question 18
Which one of the following is a monodentate ligand?

CN-
EDTA
C2O42- (oxalate ion)
H2NCH2CH2NH2 (ethylenediamine)

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Question 19
The best name for [Co(en)2Br2]Br is ________.

cobalt(III)bis(ethylenediamine) bromide
dibromobis(ethylenediamine)cobalt(III) bromide
dibromidedi(ethylenediamine)cobalt(III) bromide
dibromodiethylenediaaminecobalt(III) bromide
tribromobis(ethylenediamine)cobalt(III)

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Question 20
The correct formula for the dichlorobis(ethylenediamine)chromium(III) ion is ________.

[Cr(en)2Cl2]3+
[Cr(en)Cl2]+
[Cr(en)2Cl2]2+
[Cr(en)2Cl2]+
[Cr(en)3Cl2]+