Chemistry 223
Exam 1
Spring 2012
April 26, 2012
Oregon State University
Drs. Nafshun, Watson, Richardson
Instructions: You should have with you several number two pencils, an eraser, your 3" x 5" note
card, a calculator, and your University ID Card. If you have notes with you, place them in a
sealed backpack and place the backpack OUT OF SIGHT or place the notes directly on the table
at the front of the room.
Fill in the front page of the Scantron sheet with your last name, first name, middle initial, student
identification number, and section number (below). Leave the test form number number blank.
Section 001 (MWF 8am with Dr. Nafshun)
Section 002 (MWF 9am with Dr. Nafshun)
Section 003 (MWF 11am with Dr. Watson)
Section 004 (MWF 1pm with Dr. Richardson)
Section 005 (MWF 3pm with Dr. Nafshun)
This exam consists of 22 multiple-choice questions; each has 5 points attached. The last
question (Question 23) has 2 points attached. When you finish this exam, proceed to the proctor.
Submit your completed Scantron form. You may take your notecard and exam packet with you.
Ka[CH3COOH (aq)] = 1.80 x 10-5
(acetic acid)
Ka[CH2ClCOOH (aq)] = 1.40 x 10-3
(chloroacetic acid)
Ka[HF (aq)] = 6.30 x 10-4
(hydrofluoric acid)
Ka[HCOOH (aq)] = 1.80 x 10-4
(formic acid)
Ksp [PbF2] = 3.6 x 10-8
Ksp [Cd(OH)2] = 7.2 x 10-15
Ksp [CaSO4] = 2.4 × 10-5
Ka[C6H5COOH (aq)] = 6.30 x 10-5
(benzoic acid)
Kb[NH3 (aq)] = 1.80 x 10-5
(ammonia)
Ka[CH3CH2CH2CH2COOH (aq)] = 1.45 x 10-5
(pentanoic acid)
Kb [CH3CH2NH2] = 5.37 x 10-4
(ethylamine)
Ksp [MgF2] = 3.7 x 10-8
Ksp [PbI2] = 1.4 x 10-8
Ksp [CaC2O4] = 2.3 × 10-9
1.
Consider a 0.0100 M C6H5COOH (aq) solution. Which of the following is FALSE?
(A)
(B)
(C)
(D)
(E)
2.
C6H5COO- (aq) is the conjugate base
[H3O+] is significantly greater than [C6H5COOH]
H2O (l) is a Bronsted-Lowry base
C6H5COO- (aq) is a Bronsted-Lowry base
[H3O+] is similar to [C6H5COO-]
Consider HClO4 and HClO3. Which of the following statements is FALSE?
(A)
HClO4 is a stronger acid than HClO3.
(B)
Kb for the reaction ClO4- (aq) + H2O (l) ↔ HClO4 (aq) + OH- (aq) is less than
Kb for ClO3- (aq) + H2O (l) ↔ HClO3 (aq) + OH- (aq).
(C)
The hydroxide ion concentration in 0.100 M HClO4 (aq) is greater than the
hydroxide ion concentration in 0.100 M HClO3 (aq).
(D)
The pH of 0.100 M HClO4 (aq) is less than the pH of 0.100 M HClO3 (aq).
3.
The pH of 0.030 M LiOH (aq) is:
(A)
(B)
(C)
(D)
(E)
4.
0.030
12.48
13.97
1.52
12.58
The [OH-] of 0.120 M CH3CH2CH2CH2COOH (aq), pentanoic acid, is:
(A)
(B)
(C)
(D)
(E)
2.88 x 10-11 M
1.32 x 10-3 M
1.0 x 10-14 M
7.58 x 10-12 M
2.88 x 10-12 M
5.
The pOH of 0.169 M Ca(OH)2 (aq) is:
(A)
(B)
(C)
(D)
(E)
6.
0.169
-0.772
0.772
0.471
0.338
Which one of the following aqueous solutions is acidic?
(A) NH4Cl (aq)
(B) NaF (aq)
(C) LiI (aq)
(D) KNO3 (aq)
(E) None of the above aqueous solutions will be acidic.
7.
Which of the following is TRUE?
(A)
(B)
(C)
(D)
(E)
A neutral solution contains [H2O] = [H3O+]
A neutral solution does not contain any H3O+ or OHAn acidic solution has [H3O+] > [OH-]
A basic solution does not contain H3O+
None of the above are true.
8.
9.
A student titrates a 25.00 mL sample of 0.0100 M CH3COOH (aq) with
0.0100 M NaOH (aq). Which of the following is FALSE?
(A)
The point at which the moles of base delivered equals the moles of acid is known
as the "equivalence point."
(B)
Half of the acid has been neutralized when 12.50 mL of the NaOH (aq) has been
delivered.
(C)
Even though CH3COOH is a weak acid, the reaction of CH3COOH (aq) with
NaOH (aq) proceeds nearly 100% because of the presence of the strong base.
(D)
At the equivalence point, one of the species present is a substantial amount of
hydroxide ion.
(E)
At the equivalence point, one of the species present is the conjugate base of a
weak acid. This species is not a spectator ion and results in a pH of greater than 7
at the equivalence point.
How many mL of 0.2500 M KOH are needed to completely neutralize 150.0 mL of
0.3000 M H2SO4?
(A)
(B)
(C)
(D)
(E)
22.50 mL
45.00 mL
90.00 mL
180.0 mL
360.0 mL
10.
Which of the following solutions is a good buffer system?
(A)
(B)
(C)
(D)
(E)
11.
You wish to prepare an CH3COOH (aq) buffer system with a pH of 4.24. What ratio of
CH3COO- (aq)/ CH3COOH (aq) must you use?
(A)
(B)
(C)
(D)
(E)
12.
A solution that is 0.10 M NaCl and 0.10 M HCl
A solution that is 0.10 M HCOOH and 0.10 M HCOOLi
A solution that is 0.10 M NaOH and 0.10 M HNO3
A solution that is 0.10 M HNO3 and 0.10 M KNO3
A solution that is 0.10 M HCN and 0.10 M NaCl
0.0047
0.50
0.32
2.0
3.12
The pH of a buffer system which is 0.200 M HCOOH (aq) and 0.100 M HCOONa (aq)
is:
(A)
(B)
(C)
(D)
(E)
3.44
4.05
3.74
1.87
2.22
13.
A student titrates 0.8240 grams of an unknown monoprotic acid to the equivalence point
with 38.85 mL of 0.1008 M NaOH (aq). The molecular mass of the unknown acid is:
(A)
(B)
(C)
(D)
(E)
14.
0.004753 g/mol
210.4 g/mol
204.2 g/mol
206.2 g/mol
103.1 g/mol
Skatole (below) is one of many compounds that is attractive to males of various species
of orchid bees, who apparently gather the chemical to synthesize pheromones; it is
commonly used as bait to attract and collect these bees for study. Skatole is a:
(A)
(B)
(C)
(D)
(E)
strong acid
weak acid
strong base
weak base
spectator ion
15.
16.
Give the expression for the solubility product constant for PbCl2.
[Pb 2  ][Cl  ]2
(A)
[PbCl 2 ]
(B)
[PbCl 2 ]
[Pb 2  ][Cl  ]2
(C)
[Pb2+][Cl⁻ ]2
(D)
[Pb 2  ]2 [Cl  ]
[PbCl 2 ]
(E)
[Pb2+]2[Cl⁻ ]
Determine the molar solubility of CaSO4 in a solution containing 0.100 M Na2SO4.
(A)
(B)
(C)
(D)
(E)
4.9 × 10-3 M
2.4 × 10-4 M
1.4 × 10-5 M
1.2 × 10-5 M
0.10 M
17.
The molar solubility of Ag2S is 1.26 × 10-16 M in pure water. Calculate the Ksp for Ag2S.
(A)
(B)
(C)
(D)
(E)
18.
1.59 × 10-32
2.00 × 10-48
3.18 × 10-32
3.78 × 10-12
8.00 × 10-48
A solution containing CaCl2 is mixed with a solution of Li2C2O4 to form a solution that is
2.1 × 10-5 M in calcium ion and 4.75 × 10-5 M in oxalate ion. What will happen once
these solutions are mixed?
(A)
A precipitate will form since Q > Ksp for calcium oxalate.
(B)
Nothing will happen since both calcium chloride and lithium oxalate are soluble
compounds.
(C)
Nothing will happen since calcium oxalate is extremely soluble.
(D)
Nothing will happen since Ksp > Q for all possible precipitants.
(E)
There is not enough information to determine.
19.
What is the name of the complex [Cr(en)2(OH2)Cl]Cl2?
(A) diethylenediaminebis(aquachloro)chromium(III) chloride
(B) aquachlorobis(ethylenediamine)chromium(III) chloride
(C) chloroaquabis(ethylenediamine)chromate(III) chloride
(D) aquachlorobis(ethylenediamine)chromium(II) dichloride
(E) aquachloridebis(ethylenediamine)chromium(III) chloride
20.
21.
The formula of potassium hexacyanoferrate(II) is:
(A)
K[Fe(CN)6]
(B)
K2[Fe(CN)6]
(C)
K3[Fe(CN)6]
(D)
K4[Fe(CN)6]
(E)
K6[Fe(CN)6]
What is the coordination number of the metal ion in [Fe(en)2(OH2)F]Cl2?
(A)
(B)
(C)
(D)
(E)
1
2
4
5
6
22.
23.
Which of the following is FALSE?
(A)
[Co(H2O)6]3+ is octahedral.
(B)
[Ag(NH3)2]+ is linear.
(C)
EDTA is a hexadentate ligand.
(D)
Zn2+ is the Lewis Base in [ZnCl2F4]4- for it is the electron pair donor .
(E)
The figure below can represent the coordination compound [Co(ox)3]4-.
My least favorite thing about being in CH 223 is...
(A)
My liberal arts friends think I'm really smart and they always ask me to help them
with their homework.
(B)
Now I glow in the dark.
(C)
The permanent goggle marks.
(D)
There are too many pHuns.
(E)
My TA won't let me play with the HF.
[Any response to Question 23 will receive full credit; even no response]