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Chemistry 40S:

Final Examination

Part A: True or False  Indicate whether the sentence or statement is true or false. (10 marks)

1: The oxidation number of H in H2O is +2.                                                              True / False

2: A basic substance dissociates into [OH-] ions in water.                                       True / False

3: The p sublevel contains 5 orbitals.                                                                       True / False

4: The rate determining step is always the fastest step.                                          True / False

5: The reaction rate is always positive, even during the decomposition of a reaction. True / False

6: If the equilibrium constant, Keq , is equal to 3.4x10-8 , reactants will be favoured at equilibrium . True / False

7: At equilibrium, the concentrations of the reactants and products are always equal. True / False

8: The conjugate base for H3 PO4  is H2 PO4- . True / False

9: The pH of [H3O+] = 1.86x10-5  is equal to approximately 4.73. True / False

10: Chemistry is my favourite subject ever, and Mr. Zadra is a legend.                  True / False

Part B: Multiple Choice - Circle the best answer.                                                     (20 marks)

1.) What volume of 0.50 M KOH would be required to completely neutralize 500 mL of 0.25 M H3 PO4 solution?

a)  250 mL

b)  83 mL

2.) Reduction is defined as:

a)  the loss of electrons and a decrease in oxidation number

b)  the loss of electrons and an increase in oxidation number

3.) The oxidation number of Cl in Cl2O7  is:

a)  +14

b)  +7

c)   750 mL

d)  520 mL

c)  the gain of electrons and a decrease in oxidation number

d)  the gain of electrons and an increase in oxidation number

c)   +3

d)  -7

4.) Using the following reaction, identify the oxidizing agent:

VO2+  + MnO4-    VO2+  + Mn2+

a)  MnO4-

b)  V+4

c)   VO2+

d)  Mn2+

5.) Which of the following substances has low solubility in water?

a)  NH4OH

b)  CaCO3

6.) Schrödinger’s quantum model of the atom states that:

a)  electrons travel in a planetary like    elliptical around a positively charged nucleus

b)  electrons have a probability of    existing in a 3D space in regions called orbitals

KNO3

Na2SO4

the atom is a sphere of positive charge with negatively charged electrons stuck inside

a cat is considered neither dead nor alive when placed in a sealed box   with a vat of poison

7.) Which electron configuration represents chlorine?

a)   1s22s22p63s23p5

b)   1s22s22p63s23p1

c)   1s22s22p63s2

d)   1s22s22p63s23p6

8.) Which of the following ions have the largest ionic radius?

a)  Br -

b)  Na+

c)   I -

d)  K+

9.) Given the following reaction mechanism, what is the equation for the overall reaction?

2A  B + 2C   B + C  D + E C + D  E + F

a)  2A  2E + F

b)  2A + B + 2C  D + 2E + F

(slow)

(fast)

(fast)

c)  2A + 2C  2E + F

d)  2A + C  2E + F

10.) For a reaction 2A + B  2C, with the rate equation: Rate = k[A]2[B]:

a)  the order with respect to A is 1, and the overall order is 1

b)  the order with respect to A is 2, and the overall order is 3

c)  the order with respect to A is 2, and the overall order is 2

d)  the overall order with respect to B is

1 and the overall order is 2

11.) A reaction quotient, Qc , is calculated to be 3.2x10-5 . The equilibrium constant, Keq , for the same reaction is 5.4x10-3 . Which statement is correct?

a)  the system is at equilibrium

b)  the concentration of the products are greater than their concentrations at   equilibrium

c)  the system will attain equilibrium by moving to the right

d)  the system will attain equilibrium by moving to the left

12.) In the following equilibrium reaction, what will happen to the equilibrium status of the system if the pressure increases?

2IBr(g)    I2(g)  + Br2(g)

a)  the concentration of IBr will increase

b)  there will be no change to the equilibrium system

c)  the concentration of Br2 will decrease

d)  the concentration of I2 will increase

13.) If the concentration of Br2  increases in the previous question, what will happen to the equilibrium status?

a)  the reaction will shift to the left

b)  there will be no change to the equilibrium system

c)   the reaction will shift to the right

d)  both products and reactants will be favoured

14.) For the following reaction, if initially [A] = 1.5 mol/L and [B] = 1.5 mol/L, what is the equilibrium concentration of C, if Kc  = 41.3?

A(g)  +B(g)    2C(g) , Kc  = 41.3

a)  0.36 M

b)  0.18 M

c)   1.1 M

d)  2.3 M

15.) If the solubility of PbSO4  in water is 1.15x10-4  M, calculate the Ksp for PbSO4 :

a)   1.15x10-4

b)   1.32x10-8

c)   5.62x10-6

d)  4.45x10-4

16.) What is the Bronsted-Lowry definition of a base?

a)  a substance that accepts protons                       c)   a substance that dissolves in water

b)  a substance that dissolves in water                          to form H+  ions

to form OH-  ions

17.) What is the conjugate acid of H2 PO4-(aq)?

a)  H3O+(aq)

b)  OH-(aq)

d)  a substance that donates protons

c)   H3 PO4(aq)

d)  HPO42-(aq)

18.) What is the pOH of a 0.0050 mol/L solution of HNO3 :

a)  2.30

b)   11.6

c)   0.99

d)   13.0

19.) Use the following acid ionization constants to identify the correct decreasing order of base strengths:

HF       Ka  = 7.2x10-4

HNO2    Ka  = 4.5x10-4

HCN    Ka  = 6.2x10-10

a)  NO2-  > F- > CN-                                                                                        c)   F-  > CN-  > NO2-

b)  CN-  > NO2-  > F-                                                                                        d)  F-  > NO2-  > CN-

20.) Calculate the percent ionization of a 1.2 M HF solution, where [H3O+] = 0.028 M.

a)  2.3 %

b)  4.2 %

c)   0.24 %

d)  0.84 %

Part C: Short Answer  Answer the following questions and make sure to show all your work!

1.) Using the following oxidation-reduction reaction:

Al + NO2-    Al(OH)4-  + NH3

a)  Determine the oxidation numbers of all species.

(38 marks)

(2 marks)

b)  Balance the redox reaction in basic conditions.                                          (4 marks)

2.) In a neutralization reaction, 40.8 mL of 0.106 mol/L of sulfuric acid (H2SO4) neutralizes potassium hydroxide solution.

a)  Write the balanced chemical equation for the neutralization reaction.        (2 marks)

b)  Determine the mass of potassium hydroxide used in the reaction.             (3 marks)

3.) Write the electron configuration for a chlorine atom.                                          (1 mark)

4.) Draw the orbital diagram for Gallium (Ga). Make sure to organize each orbital by increasing energy. (2 marks)

5.) Using your knowledge of period trends, compare the potassium atom and the bromine atom and predict the following:

b)  Which would have a larger ionic radius? Explain.                                       (1 mark)

6.) The following data was obtained for the reaction:

CH3COCH3  + I2    CH3COCH2 I + HI

 

a)  Determine the rate expression, including the order with respect to each of the reactants. (2 marks)

b)  What is the overall order of this reaction?                                                   (1 mark)

c)   Calculate the specific rate constant (including units).                                 (2 marks)

7.) Consider the following reaction mechanism:

H2O2  + I-    H2O + IO-                     (slow)  ΔH = 45 kJ

H2O2  + IO-    H2O + O2 + I-       (fast)   ΔH = 35 kJ

a)  Determine the overall, net equation?

b)  Determine any intermediates or catalysts.                                                  (1 mark)

c)   Draw a potential energy diagram for the reaction, where the entire reaction is          endothermic. Label the activation energy and ΔH values.                          (2 marks)

 

d)   In which step would a catalyst be most useful?                                          (1 mark)

8.) Consider the following equilibrium reaction:          2NO(g)  + O2(g)    2NO2(g)

a)  Write the Kc equilibrium expression.

Kc  = 6.45x105

(2 marks)

b)   Explain how you know products are favoured at equilibrium .                                   (1 mark)

9.) Predict the effect of the following changes on the equilibrium for the following reaction: CO(g) +  2H2(g)    CH3OH(g) + heat

a)   increase in temperature                                                                                                (1 mark)

b)   decrease in pressure

(1 mark)

c)   addition of [CO(g)]

(1 mark)

10.) The initial concentration of morphine (a base), C17 H19 NO3 , in a solution is 3.6x10-3  M. The pOH of the solution is 4.53.

a)  Calculate Kb for morphine.

(4 marks)

b)  Calculate the percent ionization of morphine.                                              (2 marks)