CHEM 101: PRACTICE FINAL EXAM

Note: Answers to this practice final will be posted in the Nucleus. See Chemistry website for

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PART 1) MULTIPLE CHOICE

1) Dalton’s Law of Partial Pressures states that the total pressure for a gas is given by:

a) the van der Waals equation b) the sum of the individual vapour pressures

c) the sum of the partial pressures d) the molecular velocity of all gases

2) Hess’s Law can be paraphrased as:

a) you can’t win

b) that the momentum and position of an electron can’t be determined simultaneously

c) entropy is the disorder of the Universe

d) enthalpy is a state function and overall it is independent of the number of steps

3) The relationship between pressure and volume for gases is:

a) Boyle’s Law b) Charles’ Law c) Avogadro’s Law d) Graham’s Law

4) The molarity of a solution that contains 14.7 g of H2SO4 (MW = 98.078 g/mol) in 200 mL

solution is:

a) 7.4 M b) 1.5 M c) 0.75 M d) 0.77 M e) 3.0 M

5) If a 20 mL solution of an unknown acid requires 24.3 mL of 0.100 M NaOH to reach

neutralization, what is the concentration of the unknown acid?

a) 0.055 M b) 0.243 M c) 0.122 M d) 0.068 M

6) Arsenic acid, H3AsO4, is used industrially to manufacture insecticides. Arsenic acid is a

polyprotic acid with Ka1=2.5 x 10-4

, Ka2=5.6 x 10-8

, and Ka3=3 x 10-13

. What is the concentration

of HAsO4 in a solution whose initial arsenic acid concentration was 0.35 M?

a) 9.4 x 10-3

M b) 2.5 x 10-4

M c) 8.8 x 10-5

M d) 5.6 x 10-8

M

7) In the hydrolysis of water by fluoride ions, the products will include:

a) H2O b) F- c) OH- d) none of the above

8) In which compound does iodine have an oxidation state of +3?

a) HIO3 b) I2 c) IF5 d) HI

9) The oxidation state of aluminum in the complex ion AlCl4- is:

a) 4 b) -4 c) -3 d) 3 e) none of the above

10) What is the maximum amount of sodium sulfate (Na2SO4) that can be added to 1.00 L of

0.0020 M Ca(NO3)2 before precipitation of calcium sulfate begins (Ksp=2.4 x 10-5

)?

a) 1.2 x 10-2

mol b) 3.5 x 10-3

mol c) 4.9 x 10-3

mol d) 1.2 x 10-5

mol

11) A voltaic cell is prepared using copper and silver, as shown:

Cu (s) | Cu2+

(aq) || Ag+

(aq) | Ag(s)

Which one of the following reactions occurs at the cathode?

a) Cu (s) Cu2+

(aq) + 2e-

b) Cu2+

(aq) + 2e- Cu (s)

c) Ag (s) Ag+ (aq) + e-

d) Ag+ (aq) + e- Ag (s)

12) The value of E°cell for

Cr (s) | Cr3+

(aq) || Hg2+

(aq) | Hg (l)

is 1.59 V. Calculate ∆G° for the reaction at 25°C.

a) -920 kJ b) -767 kJ c) -460 kJ d) -307 kJ

13) Which of the following combinations of signs for ∆H and ∆S will always result in a reaction

being nonspontaneous?

a) ∆H +, ∆S –

b) ∆H -, ∆S +

c) ∆H -, ∆S -

d) ∆H +, ∆S +

e) Cannot be determined without temperature

14) The vapour pressure of 1-butene is 1.268 atm at 273.15 K and its heat of vaporization is 22.9

kJ/mol. What is the normal boiling point of 1-butene?

a) 266.9 K

b) 270.4 K

c) 276.0 K

d) 279.1 K

15) Data for the reaction A + B C are given below. What is the rate constant for this system?

Experiment [A] (M) [B] (M) Initial Rate (M s-1

)

1 0.030 0.060 2.5 x 10-5

2 0.030 0.020 2.5 x 10-5

3 0.060 0.060 10.0 x 10-5

a) 2.8 x 10-2

M-1

s-1

b) 2.8 x 10-2

M s-1

c) 2.8 x 10-2

M2 s

-1

d) 1.7 x 10-3

M-1

s-1

e) 1.7 x 10-3

M s-1

16) If a catalyst is added to a reaction

I) the value of k is increased

II) the value of k is decreased

III) the rate is increased

IV) the rate is decreased

V) neither rate nor the constant are changed, only the order

a) I and IV

b) II and IV

c) II and III

d) I and III

e) V only

17) The correct units of the specific rate constant for a zero order reaction are:

a) L/mol-sec

b) sec-1

c) sec

d) mol2/L

2sec

e) none of the above

18) If the half-life of a reactant is independent of its initial concentration, the reaction order is:

a) 0 b) 0.5 c) 1 d) 2 e) 3

19) The rate law for the rearrangement of CH3NC to CH3CN at 800 K is

Rate = 1300 s-1

[CH3NC]

What is the half-life of the reaction if the initial concentration of CH3NC is 0.40 M?

a) 1.92 x 10-3

s b) 520 s c) 1875 s d) 5.33 x 10-4

s

20) The first order reaction A products has a half-life of 150 seconds. What percent of the

sample remains unreacted after 300 sec?

a) 25% b) 50% c) 12.5% d) 0.0% e) 75%

21) Which of the following is NOT a Lewis base?

a) OH-

b) (C2H5)B c) CH3NH2 d) NH3

22) Molecular orbital theory combines atomic orbitals to form:

a) bonding/anti-bonding pairs b) hybrids such as sp3 and d

2sp

3

c) VSEPR-based molecular shapes c) lattice structures for ions

23) Markovnikov’s rule states that in an addition reaction:

a) the carbocation will form on the least substituted carbon atom

b) the carbocation will form on the most substituted carbon atom

c) H+

will add to the sp2 carbon that is bonded to the least number of hydrogens

d) Markovnikov didn’t play by the rules

PART 2) TITRATION

Answer the following titration question, which has 5 parts (20 marks)

A 400 mL sample of benzoic acid, a weak acid (C6H5COOH; Ka=6.3 x 10-5

), is titrated by the

strong base, NaOH. The initial concentrations of the two species are:

[C6H5COOH] = 0.200 M [NaOH] = 0.200 M

What is the pH of the solution:

a) Initially?

b) After 199 mL of NaOH has been added to the acid?

c) After 200 mL of NaOH has been added to the acid?

d) At the equivalence point?

e) After 550.0 mL of NaOH has been added to the acid?

PART 3) LONG ANSWERS

1) Answer either (i) OR (ii) of the following:

(i) At 850°C, the equilibrium constant, Kp, for the reaction

C (s) + CO2 (g) ⇄ 2CO (g)

is 10.7. If the total pressure in the system at equilibrium is 1.000 atm, what is the

partial pressure of carbon monoxide?

(ii) At a temperature of 25°C and a pressure of 1 bar, a gas has a density of 2.00 g/L.

What is the molar mass of the gas?

2) Answer either (i) OR (ii) of the following:

(i) What is the molecular weight of a gas that has a molecular velocity of 515.4 m/s at

25°C? What is the effusion rate of this gas compared to oxygen?

(ii) If the relative effusion rate of a gas compared to oxygen is 1.173, what is its velocity

at STP?

3) Answer either (i) OR (ii) of the following: (i) Cinnamaldehyde (MW = 132.15 g/mol) is used as a flavouring agent. What mass of

cinnamaldehyde must be added to 175 g of ethanol to give a solution whose boiling

point is 82.7°C? Kb = 1.22°C/m; boiling point of pure ethanol = 78.5°C.

(ii) What is the freezing point of a solution containing 2.87 g of benzene (MW = 78.11

g/mol) dissolved in 50.0 g of p-dichlorobenzene (MW = 147.0 g/mol), given that the

freezing point of p-dichlorobenzene is 53.0°C and Kf = 7.10 K/m?

4) Answer either (i) OR (ii) of the following:

(i) What is the pH of a 0.0263 M solution of carbonic acid? (Ka1 = 4.2 x 10-7

; Ka2 = 4.8 x

10-11

)

(ii) The titration of a 75.0 mL sample of a di-protic acid requires 24.2 mL of 0.200 M

KOH. What is the concentration of the acid?

5) Answer either (i) OR (ii) of the following:

(i) A solution is prepared containing 0.020 M Ag+

and 1.5 M NH3. Kf for [Ag(NH3)2+ is

1.6 x 107. What is the concentration of Ag

+ in this solution?

(ii) Solid AgNO3 (aq) is slowly added to a solution containing 0.115 M NaCl and 0.264

M NaBr in a fractional or selective precipitation experiment. What percentage of

bromide will be removed before the silver chloride starts to precipitate?

AgCl: Ksp = 1.8 x 10-10

AgBr: Ksp = 5.0 x 10-13

6) Answer either (i) OR (ii) of the following:

(i) Consider the reaction:

H2X (g) HX (g) + X (g)

∆H° = 18.4 kJ/mol; ∆S° = 23.1 J/molK

What is Keq for this reaction at 525 K?

(ii) Consider the reaction:

2NO2 (g) ⇄ N2O4 (g)

∆H° = -56.8 kJ/mol; ∆S° = -175 J/molK

In a container (at 298 K), N2O4 (g) and NO2 (g) are mixed with initial partial

pressures of 2.4 atm and 0.42 atm, respectively. What is the pressure of each of these

gases at equilibrium?

7) Answer either (i) OR (ii) of the following:

(i) In the second order reaction, A products, [A] = 0.500 M initially and 0.225 M after

18.0 minutes. What is the half-life of the reaction if the initial concentration is 0.750

M?

(ii) For the reaction 2N2O5 (g) 4NO2 (g) + O2 (g), the rate law is:

Rate=k[N2O5]

At 310 K, the half-life is 2.50 x 104 seconds and the activation energy is 103.3

kJ/mol. What is the half-life at 360 K?

PART 4) ORGANIC CHEMISTRY

Give the major product(s) of the following reactions.

1. Hg(OAc)2, H2O

2. NaBH4

1. BH3

2. H2O2, NaOH, H2O

KMnO4, H3O+

KMnO4, H3O+

HBr

Ether

+ H2O

H2SO4

HgSO4

Cl2

KMnO4

NaOH, H2O