Houston Community College System
Departmental
SAMPLE
Final Examination
Chemistry 1412
1
PART I (2 points each)
Multiple choice - Please DO NOT write or mark on this paper. Write your
correct answer on scantron.
1. In which colligative property (ies) does the value decrease as more solute is added?
A. boiling point
B. freezing point
C. vapor pressure D. freezing point and vapor pressure
2. What is the molarity of a solution prepared by dissolving 25.2 g CaCO3 in 600. mL of a water solution?
A. 0.420 M
B. 0.567 M
C. 0.042 M
D. 0.325 M
3. What is the freezing point of an aqueous glucose solution that has 25.0 g of glucose, C6H12O6, per
100.0 g H2O (Kf = 1.86°C /m)?
A. 0.258
B. -0.258
C. 2.58
D. -2.58
4. What is the osmotic pressure in atm produced by a 1.20 M glucose (C6H12O6) solution at 25°C?
A. 29.3
B. 4.89
C. 25.1
D. 36.0
5. The vapor pressure of pure ethanol at 60°C is 349 mm Hg. Calculate vapor pressure in mm Hg at 60°C for a
solution prepared by dissolving 10.0 mol of naphthalene (nonvolatile) in 90.0 mol of ethanol?
A. 600
B. 314
C. 34.9
D. 69.8
6. For first-order reactions the rate constant, k, has the units
A. M s-1
B. M-1 s-1
C. M-2 s-1
D. s-1
7. For second-order reactions the slope of a plot of 1/[A] versus time is
A. k
B. k/[A]0
C. kt
D. -k
8. If the reaction 2A + 3D  products is first-order in A and second- order in D, then the rate law will have
the form rate =
A. k[A]2[D]3
B. k[A][D]
C. k[A]2[D]2
D. k[A][D]2
9. In the first-order reaction A  products the initial concentration of A is 1.56 M and the concentration is
0.869 M after 48.0 min. What is the value of the rate constant, k, in min-1?
A. 3.84 x 10-2
B. 2.92 x 10-2
C. 5.68 x 10-2
D. 1.22 x 10-2
10. Consider the reaction 2HI(g)  H2(g) + I2(g). What is the value of the equilibrium constant, Kc, if at
equilibrium,
[H2] = 6.50 x 10-7 M, [I2] = 1.06 x 10-5 M, and [HI] = 1.87 x 10-5 M?
A. 3.68 x 10-7
B. 1.97 x 10-2
C. 1.29 x 10-16
2
D. 50.8
11. Given the following mechanism, determine which of the species below is a catalyst?
I)
III)
A.
C + ClO2  ClO + CO
ClO + O2  ClO2 + O
ClO2
B.
CO2
II)
IV)
C.
CO + ClO2  CO2 + ClO
ClO + O  ClO2
O
D. CO
12. For the system CaO(s) + CO2(g)  CaCO3(s) the equilibrium constant expression for Keq is
A.
[CO2]
B. 1 / [CO2]
C. [CaO] [CO2] / [CaCO3]
D.
[CaCO3] / [CaO] [CO2]
13. The value of Kp for the reaction 2NO2(g)  N2O4(g) is 1.52 at 319 K. What is the value of Kp at
this temperature for the reaction N2O4(g)  2NO2(g)?
A. -1.52
B. 1.23
C. 5.74 x 10-4
14. Which of the following is true for the cell shown here?
D. 0.658
Zn(s)  Zn2+(aq)  Cr3+(aq)  Cr(s)
A. the electrons flow from cathode to the anode
B. the electrons flow from the zinc to the chromium
C. the electrons flow from the chromium to the zinc D. the zinc is reduced
15. How many electrons are transferred in the following reaction? 2ClO3- + 12H+ + 10I-  5I2 + Cl2 + 6H2O
A. 10
B. 12
C. 5
D. 30
16. A voltaic cell has an E0 value of +1.00 V. The reaction :
A. is not spontaneous B. has K =1
C. has a negative G0
D. has G0 = 0
17. Which energy conversion below takes place in a galvanic cell?
A. electrical to chemical
B. chemical to electrical C. mechanical to chemical D. electrical to mechanical
18. The value of Kc for the reaction C(s) + CO2(g)  2CO(g) is 1.6. What is the equilibrium concentration of
CO if the equilibrium concentration of CO2 is 0.50 M?
A. 0.31
B. 0.80
C. 0.89
D.
0.75
19. Consider the reaction below:
2SO3(g)  2SO2(g) + O2(g) ,  H° = +198 kJ
All of the following changes would shift the equilibrium to the left except one. Which one would not
cause the equilibrium to shift to the left?
A. removing some SO3
C. increasing the container volume
B. decreasing the temperature
D. adding some SO2
3
20. Calculate the pH of a solution if its [OH] = 0.000700 M and indicate whether the solution is
acidic, basic, or neutral.
A. 3.15, acidic
B. 17.2, basic
C. 10.8, basic
D. 11, basic
21. Which one of the conjugate bases of the following Brønsted-Lowry acids are incorrect?
A. ClO- for HClO
B. HS- for H2S
C. H2SO4 for HSO4-
D. NH3 for NH4+
22. Predict whether aqueous solutions of the following compounds are acidic, basic, or neutral. Find
the incorrect answer.
A. KNO3 (neutral)
B. NaC2H3O2 (basic)
C. KClO (acidic)
D. NaCN (basic)
23. Calculate the pH of a buffer that is 0.20 M in formic acid and 0.15 M in sodium formate
(Ka = 1.8 x 10-4).
A. 2.4 x 10-4
B. 3.63
C. 0.82
D. 8.33
24. If X is the solubility of a salt in moles per liter, which one of the following Ksp expressions is
incorrect?
A. Ag2S, Ksp = 4X3
B. AgCl , Ksp = X2 C. BaSO4 , Ksp = 4 X2
D. Cu(OH)2 , Ksp = 4X3
25. For each of the following processes, predict whether entropy, S, is positive or negative:
(i) 2K(s) + Br2(l)  2KBr(s),
(ii) 2MnO2(s)  2MnO(s) + O2(g)
A. (i) positive, (ii) positive
D. (i) positive, (ii) negative
B. (i) negative, (ii) positive
D. (i) negative, (ii) negative
26. Using the given values of S° ( J/mol.K) , calculate the value of S° for the reaction,
C2H4(g) + H2(g)  C2H6(g)
S0 = 219.4
A. -120.5 J/ K
B. 120.5 J/ K
130.58
229.5
C. 10.1 J/ K
D. -10.1 J/ K
27. Consider a galvanic cell based on the reaction below, what is the coefficient of Fe3+ in the
balanced equation in acidic solution?
Fe2+ + Cr2O72-  Fe3+ + Cr3+
A. 1
B. 2
C. 3
D. 6
28. The standard reduction potentials for the following half reactions are given as follows;
Cr3+ + 3e-  Cr(s)
Br2 + 2e-  2Br-
E0 = -0.73 V
E0 = +1.09 V
What is the E0 for a voltaic cell using these reactions?
A. 1.82 V
B. 0.36 V
C. 4.75 V
4
D. 1.79 V
29. Which of the following represents positron?
A.
1
1
H
B.
0
-1
e
C.
0
+1
e
D.
4
2
He
30. Which of the following balanced equation is labeled incorrectly?
A. Beta decay,
239
92
U 
239
93
Np + 0-1 e
B. Alpha Bombardment, 2411 Na + 42 He 
C. Electron capture,
7
4
Be + 0-1e 
7
3
27
13
Al +10 n
Li
D. All are correctly labeled
31. Which of the following pairs is incorrect ?
A. ethane - C2H6
B. hexane - C6H14
C. decane - C10H22
32. Which of the following is general formula for alkene with
A. CnHn
B. CnH2n+2
D. heptane - C7H14
n-carbon atoms ?
C. CnH2n
D. CnH2n-2
33. Classify the following molecule;
CH3 -CH2 - C= O

OCH3
A. ester
B. aldehyde
C. ketone
D. carboxylic acid
34. What is the correct IUPAC name the following compound;
Cl
CH2CH3
C=C
H3C
A. cis-2-chloro-3-chloro-2-pentene
C. trans-2,3-dichloro-2-pentene
Cl
B. 2,3-dichloro-1-methylbutene
D. 1-chloro-2-methylbutene
35. Which of the following is correct condensed formula for isopropanol
A. CH3- CH2 -CH2 OH
CH3

C. CH3- C -CH2OH

CH3
B. CH3 -CH -CH3

OH
D. CH3 - H2C = CH-OH
5
Part II-( 5 points each)
Show work- Please write your complete work in space provided. Partial credit will be given.
1. A solution is prepared by dissolving 6.00 g of an unknown nonelectrolyte in enough water to make 1.00 L of
solution. The osmotic pressure of this solution is 0.750 atm at 25.0°C. What is the molecular weight of the
unknown solute (R = 0.0821 L·atm/K·mol)?
2. Initial rate data were obtained for the following reaction:
A(g) + 2B(g)  C(g) + D(g)
initial
Experiment
1
2
3
initial
initial
[A], mol/L [B], mol/L
0.15
0.30
0.15
0.10
0.10
0.20
rate ,Ms-1
0.45
1.8
0.9
What are the rate law and k value for the reaction?
3. If the pH of a solution is 6.30, what are the molar concentrations of H+(aq), OH-(aq) , and pOH in the
solution?
6
4. A 50.0-mL sample of 0.50 M acetic acid, CH3COOH, is titrated with a 0.150 M NaOH solution.
Calculate the pH after 25.0 mL of the base have been added (Ka = 1.8 x 10-5).
5. If a constant current of 5.0 amperes is passed through a cell containing Cr3+ for 1.0 hour, how many
grams of Cr will plate out on to the cathode? (the atomic mass of Cr is 51.996 and 1 Faraday = 96485 coulombs)
6.The half-life of Sr-90 1s 28.1 years. How long will it take a 10.0 g sample of Sr-90 to decompose
to 0.10 g?
7
ANSWERS TO CHEMISTRY FINAL SAMPLE EXAM
Part I -Multiple Choice Questions (2 points each)
1. D
2. A
3. D
4. A
5. B
6. D
8. D
9. D
10. B
11. A
12. B
13. D
15. A
16. C
17. B
18. C
19. C
20. C
22. C
23. B
24.C
25. B
26. A
27. D
29. C
30. D
31. D
32. C
33. A
34. C
Part II – Show work
1.
(0.750 atm)
π = MRT and M = π /RT = _____________________________________ = 0.0307M
(0.0821 L-atm/mol-K)(298K)
n
massunk
massunk
(6.00 g)
M = ________  n = MxV = ______________  MWunk = ____________ = ________________________ = 196 g/mol
V
MW unk
MxV
(0.0307M)(1.00L)
OR:
(g) ( R) (T)
(6.00) (0.0821) ( 298)
MW = ---------------- = ---------------------------- = 196 g/mol
π V
(0.750) ( 1.00)
2. EXP 1 & 2: Concentration of A is doubled, concentration of B is kept constant, initial rate increases
by a factor of 4. That means that the reaction is second order in A.
EXP 1 & 3: Concentration of A is kept constant, concentration of B is doubled, initial rate increases
by a factor of 2. That means that the reaction is first order in B. Rate = k [A] 2[B]
EXP 1: 0.45 Ms-1 = k (0.15M)2(0.10M)  k = 200 M-2s-1
3.
pH = 6.30 [H+] = antilog (-6.30) = 5.01 x 10-7 M
pOH = 14.00 – 6.30 = 7.70  [OH-] = antilog(-7.70) = 1.90 x 10-8M
OR:
[H+] = 10 –pH = 10 – 6.30 = 5.01 x 10-7 M , pOH = 14 – 6.30 = 7.70
[OH-] = 10 –pOH = 10 – 7.70 = = 1.90 x 10-8M
4.
molCH3COOH = 0.50Mx0.050L = 0.025mol , molNaOH = 0.15Mx0.025L = 3.75x10-3mol
CH3COOH(aq) + NaOH(aq)

NaC2H3O2(aq) + H2O(l)
Initial:
(0.025 mol)
(3.75x10-3mol)
0
0
Change: -(3.75x10-3mol)
-(3.75x10-3mol)
(3.75x10-3mol) (3.75x10-3mol)
Final: (2.13x10-2mol)
0
(3.75x10-3mol) (3.75x10-3mol)
CH3COOH(aq) + H2O(l)

CH3COO-(aq)
+
H3O+(l)
M CH3COOH =
(2.13x10-2mol)
= 0.283M
(0.075L)
___________________
[CH3COO
_________________
pH= pKa + log
[CH3COOH]
-
]
= 3.98
(3.75x10-3mol)
M CH3COO- = ___________________ = 0.05M
(0.075L)
OR:
Ma = M(acid) = ( MaVa/Vtot) = (0.50)(0.05)/0.075 = 0.33 M
Mb = M(base) = (MbVb/Vtot) = (0.15)(0.025)/0.075 = 0.05 M
PKa = -logKa = -log (1.85x10 –5) = 4.73
For weak acid strong base ;
PH = PKa + log [Mb] / [Ma - Mb] = 4.73 + log [0.05] / [ 0.33 – 0.05] = 4.73 -0.753 = 3.98
5.
6.
Charge = (5.0Amp)(3600sec) = 18,000C
Moles of e- = 18,000C x (1 mol e-/96485C) = 0.18656 mol e- = 0.06219 mol Cr
0.06219 mol Cr = 3.233 g Cr
OR :
Mass ( g Cr) = ( M/n) ( It/F) = ( 52/3) (5x3600/96485) = 3.233 g Cr
k =( 0.693/28.1yr) = 2.47 x 10-2 yr-1
ln[0.10] = -(2.47 x 10-2 yr-1)(t) + ln[10.0]  t = 186 yr.
OR: t = (3.32)(t½ ) ln ( mo / mn)
, t = ( 3.32) ( 28.1) log ( 10.0/0.10) , t = 186 yr.
8
7. A
14. B
21. C
28. A
35. B