KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS
CHEMISTRY DEPARTMENT
 
CHEM-102-072-FIRST MAJOR
 

Important constants
Gas Constant (R)
= 0.0821
= 8.3145
= 8.31 x 107
L.atm/(mol.K)
J/(mol.K)
g.cm2/(sec2.mol.K)
Planck’s Constant (h)
= 6.626 x 10-34
= 6.626 x 10-34
J.sec/particle kg.m2/(sec.particle)
Velocity of light (c)
= 2.998 x 108
m/sec
Avogadro’s number (N)
= 6.022 x 1023
particles/mole
Bohr’s Constant (RH)
= 2.179 x 10-18
J/particle
Faraday (F)
= 96485
Coulombs
Specific heat of H2O
= 4.18
J/(g.oC)

 



1.
Determine the rate law for the reaction:  
                                2NO(g)   +   Cl2(g)     2NOCl(g)
from the following experimental data.
                                                                                                Initial Rate of
                                   Initial [NO]              Initial [Cl2]             disappearance
                                                                                                      of NO
        Expt. No.                mol L-1                    mol L-1                     mol L-1 s-1
 
             1                          0.10                       0.10                       3.0 x 10-3
 
             2                          0.10                       0.20                       6.0 x 10-3
 
             3                          0.20                       0.20                       2.4 x 10-2            
 
A.
Rate = k [NO]2 [Cl2]1
B.
Rate = k [NO]2 [Cl2]2
C.
Rate = k [NO]1 [Cl2]2
D.
Rate = k [NO]1 [Cl2]1
E.
Rate = k [NO]2



2.
The reaction
                 
is first order in with a rate constant k = 1.0 x 10-5 s-1 at 45 . Starting with an initial concentration of 1.0 x 10-3 M, what will the concentration be after 5.5 x 105 s?
A.
1.0 x 10-3 M
B.
5.5 x 10-8 M
C.
1.0 x 10-5 M
D.
4.1 x 10-6 M
E.
5.5 x 10-5 M


3.
In the first-order reaction
                                A → B
25% of A react in 42 min at 25°C. The half-life of this reaction is:
A.
21 min
B.
42 min
C.
84 min
D.
120 min
E.
101 min


4.
The activation energy, Ea, of a certain reaction at 400°C is 64 kJ/mol.   In the presence of a catalyst at 400°C Ea is reduced to 55 kJ/mol. How may times is the catalyzed reaction faster assuming a constant frequency factor?
A.
5.0 times
B.
1.16 times
C.
15 times
D.
2.0 times
E.
0.2 times


5.
The following four statements were made to explain why certain collisions between molecules do not lead to a reaction.
   
1. The total energy of two colliding molecules is less than some minimum amount of energy.
2. Molecules cannot react with each other unless a catalyst is present.
3. The molecules are not properly oriented during the collision.  
4. Solids cannot react with gases.

Which of the following choices contains the two correct statements?
A.
1 and 2
B.
1 and 3
C.
1 and 4
D.
2 and 3
E.
3 and 4


6.
Nitrous oxide (N2O) decomposes at 600 °C according to the balanced equation
                                      2N2O(g) → 2N2(g) + O2(g)
Identify the catalyst(s) in the following mechanism for the decomposition reaction..
             Step 1.                              Cl2(g) → 2Cl(g)
             Step 2.               N2O(g) + Cl(g) → N2(g) + ClO(g)
             Step 3.               N2O(g) + Cl(g) → N2(g) + ClO(g)
             Step 4.              ClO(g) + ClO(g) → Cl2(g) + O2(g)
A.
Cl
B.
Cl2
C.
ClO
D.
N2O
E.
ClO and Cl


7.
A mixture of 1.00 mol H2, and 1.00 mol I2 were placed in a 2.00-L container and the reaction    
                                   2 HI (g)   ⇌   H2 (g)    +    I2 (g)
was allowed to reach equilibrium at 430 .   If the equilibrium constant is 1.842 x 10-2 , calculate the amount of HI present at equilibrium.
A.
0.787 M
B.
0.440 M
C.
0.107 M
D.
0.880 M
E.
0.120 M


8.
Solid NH4NO3 in an evacuated container was heated and the equilibrium

                       

was established. Calculate Kp for this equilibrium if the total pressure was 3.42 atm.
A.
1.25
B.
2.60
C.
1.48
D.
5.93
E.
1.6 x 102


9.
Which of the following can, when it changes, change the value of the equilibrium constant?
A.
Catalyst
B.
Concentration
C.
Pressure
D.
Temperature
E.
Volume


10.
Equilibrium is reached in chemical reactions when:
A.
the rates of the forward and reverse reactions become equal.
B.
the concentrations of reactants and products become equal.
C.
the temperature shows a sharp rise.
D.
all chemical reactions stop.
E.
the forward reaction stops.


11.
Solid calcium hydroxide, Ca(OH)2, is dissolved in water until the pH of the solution is 10.23. The calcium ion concentration [Ca2+] is:
A.
5.9 x 10-11
B.
3.4 x 10-4
C.
1.7 x 10-4
D.
8.5 x 10-5
E.
3.4 x 10-8


12.
A weak acid HA is 1.0 % dissociated in a 1.0 M solution. What would its percent dissociation be in a 5.0 M solution?
A.
0.20 %
B.
0.45 %
C.
1.0    %
D.
5.0    %
E.
0.10 %


13.
Calculate the pH of 0.30 M NH4Cl (pKb for NH3 = 4.74).
A.
9.11
B.
4.89
C.
9.78
D.
4.22
E.
5.39


14.
The conjugate acid and conjugate base of bicarbonate ion, HCO3–, are, respectively:
A.
H3O+ and OH–
B.
H3O+ and CO32–
C.
H2CO3 and OH–
D.
H2CO3 and CO32–
E.
CO32– and OH–


15.
A 0.4 mol sample of a diprotic acid, H2A, is dissolved in 250 mL of water. Ka1 of this acid is 1.0 10-5 and Ka2 is 1.0 10-10. Calculate the concentration of A2- in this solution.
A.
1.0 x 10 -5 M
B.
2.0 x 10 -5 M
C.
4.0 x 10 -3 M
D.
1.0 x 10 -10 M
E.
1.6 M


16.
How many moles of solid NaF would have to be added to 1.00 L of 2.14 M HF solution to achieve a buffer of pH 3.35? Assume there is no volume change. (Ka for HF = 7.2 10-4)
A.
3.45
B.
0.440
C.
0.750
D.
1.00
E.
1.60


17.
150.0 mL of 0.500 M HNO3 were added to 300.0 mL of 0.450 M NH3 (Kb = 1.8 10-5). The pH of the final solution is:
A.
4.84
B.
11.16
C.
6.16
D.
9.16
E.
9.35


18.
Methyl Red changes color within the pH range 4.8-6.0. For which of the following titrations will this indicator work best?
A.
0.100 M HNO3 + 0.100 M KOH
B.
0.100 M aniline (Kb = 3.8 × 10–10) + 0.100 M HCl
C.
0.100 M NH3 (Kb = 1.8 × 10–5) + 0.100 M HCl
D.
0.100 M HF (Ka = 7.2 × 10–4) + 0.100 M NaOH
E.
0.100 M acetic acid (Ka = 1.8 × 10–5) + 0.100 M NaOH


19.
How many moles of Fe(OH)2 [Ksp = 1.8 10-15] will dissolve in 1.0 liter of water buffered at pH = 10.74?
A.
6.0 x 10-9
B.
5.5 x 10-4
C.
3.0 x 10-7
D.
1.7 x 108
E.
3.3 x 10-12


20.
A solution is made by mixing 500.0 mL of 4.0 M NH3 and 500 mL of 0.40 M
AgNO3 solutions. What would the concentration of the Ag+ ions be in this
solution given that,
 
 
Ag+ + NH3 AgNH3+
 
K1 = 2.1 × 103
 
 
AgNH3+ + NH3 Ag(NH3)2+
 
K2 = 8.2 × 103
A.
0.20 M
B.
1.2 x 10-8 M
C.
4.5 x 10-9 M
D.
1.6 M
E.
1.2 x 10-9 M


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