MULTIPLE CHOICE: by G915K4

VIEWS: 43 PAGES: 9

									MULTIPLE CHOICE:
Use the following answers for questions 1-4.           (84-4-7)
   (A) Hydrofluoric acid
   (B) Carbon dioxide
   (C) Aluminum hydroxide
   (D) Ammonia
   (E) Hydrogen peroxide
1. Is a good oxidizing agent
2. Is used to etch glass chemically
3. Is used extensively for the production of fertilizers
4. Has amphoteric properties

5. The pH of 0.1-molar ammonia is approximately (84-33)
   (A) 1
   (B) 4
   (C) 7
   (D) 11
   (E) 14

6. Which of the following ions is the strongest Lewis acid? (84-48)
   (A) Na+
   (B) Cl¯
   (C) CH3COO¯
   (D) Mg2+
   (E) Al3+


7. A student pipetted five 25.00-milliliter samples of hydrochloric acid and transferred
each sample to an Erlenmeyer flask, diluted it with distilled water, and added a few drops
of phenolphthalein to each. Each sample was then titrated with a sodium hydroxide
solution to the appearance of the first permanent faint pink color. The following results
were obtained. 84-62
Volumes of NaOH Solution

   First Sample..................35.22 mL
   Second Sample..............36.14 mL
   Third Sample.................36.13 mL
   Fourth Sample..............36.15 mL
   Fifth Sample..................36.12 mL



Which of the following is the most probable explanation for the variation in the student's
results?
        (A) The burette was not rinsed with NaOH solution.
        (B) The student misread a 5 for a 6 on the burette when the first sample was
        titrated.
        (C) A different amount of water was added to the first sample.
        (D) The pipette was not rinsed with the HCI solution.
        (E) The student added too little indicator to the first sample.
   8.
                                                Acid Dissociation
Acid
                                                Constant, Ka
H3PO4                                           7 x 10¯3
H2PO4¯                                          8 x 10¯8
HPO42¯                                          5 x 10¯13
   On the basis of the information above, a buffer with a pH = 9 can best be made by using
                                             8463
        (A) pure NaH2PO4
        (B) H3PO4 + H2PO4¯
        (C) H2PO4¯ + PO43¯
        (D) H2PO4¯ + HPO42¯
        (E) HPO42¯ + PO43¯


   9. Which of the following reactions does NOT proceed significantly to the right in
   aqueous solutions?      8471
        (A) H3O+ + OH¯ ---> 2 H2O
        (B) HCN + OH¯ ---> H2O + CN¯
        (C) Cu(H2O)42+ + 4 NH3 ---> Cu(NH3)42+ + 4H2O
        (D) H2SO4 + H2O ---> H3O+ + HSO4¯
        (E) H2O + HSO4¯ ---> H2SO4 + OH¯
   10. 5 Fe2+ + MnO4¯ + 8 H+ <===> 5 Fe3+ + Mn2+ + 4 H2O
   In a titration experiment based on the equation above, 25.0 milliliters of an acidified Fe2+
   solution requires 14.0 milliliters of standard 0.050-molar MnO4¯ solution to reach the
   equivalence point. The concentration of Fe2+ in the original solution is 8479
        (A) 0.0010 M
        (B) 0.0056 M
        (C) 0.028 M
        (D) 0.090 M
        (E) 0.14 M
   11. What is the net ionic equation for the reaction that occurs when aqueous copper(II)
   sulfate is added to excess 6-molar ammonia? 8481
        (A) Cu2+ + SO42¯ + 2 NH4+ + 2 OH¯ ---> (NH4)2SO4 + Cu(OH)2
        (B) Cu2+ + 4 NH3 + 4 H2O --> Cu(OH)42¯ + 4 NH4+
        (C) Cu2+ + 2 NH3 + 2 H2O --> Cu(OH)2 + 2 NH4+
   (D) Cu2+ + 4 NH3 --> Cu(NH3)42+
   (E) Cu2+ + 2 NH3 + H2O --> CuO + 2 NH4+



Use these answers for questions 12-14.                                     89-8-10
   (A) a solution with a pH less than 7 that is not a buffer solution
   (B) a buffer solution with a pH between 4 and 7
   (C) a buffer solution with a pH between 7 and 10
   (D) a solution with a pH greater than 7 that is not a buffer solution
   (E) a solution with a pH of 7
Ionization Constants
   CH3COOH = 1.8 x 10¯5
   NH3 = 1.8 x 10¯5
   H2CO3; K1 = 4 x 10¯7
   H2CO3; K2 = 4 x 10¯11
12. A solution prepared to be initially 1 M in NaCl and 1 M in HCl.
13. A solution prepared to be initially 1 M in Na2CO3 and 1 M in CH3COONa
14. A solution prepared to be initially 0.5 M in CH3COOH and 1 M in CH3COONa

15. All of the following species can function as Brönsted-Lowry bases in solution
EXCEPT (8934)
   (A) H2O
   (B) NH3
   (C) S2¯
   (D) NH4+
   (E) HCO3¯




16. As the number of oxygen atoms increases in any series of oxygen acids, such as
HXO, HXO2, HXO3, ...., which of the following is generally true? 8946
   (A) The acid strength varies unpredictably.
   (B) The acid strength decreases only if X is a nonmetal.
   (C) The acid strength decreases only if X is a metal.
   (D) The acid strength decreases whether X is a nonmetal or a metal.
   (E) The acid strength increases.


17. Which of the following characteristics is common to elemental sulfur, chlorine,
nitrogen, and carbon?                8963
   (A) They are gaseous elements at room temperature.
   (B) They have oxides that are acid anhydrides.
   (C) They have perceptible color at room temperature.
   (D) They form ionic oxides.
   (E) They react readily with hydrogen at room temperature.




18. Equal volumes of 0.10-molar H3PO4 and 0.20-molar KOH are mixed. After
equilibrium is established, the type of ion in solution in largest concentration, other than
the K+ ion, is 8974
   (A) H2PO4¯
   (B) HPO42¯
   (C) PO43¯
   (D) OH¯
   (E) H3O+


19. Which of the following acids can be oxidized to form a stronger acid?             9450
   (A) H3PO4
   (B) HNO3
   (C) H2CO3
   (D) H3BO3
   (E) H2SO3


20. It is suggested that SO2 (molar mass 64 grams), which contributes to acid rain, could
be removed from a stream of waste gases by bubbling the gases through 0.25-molar
KOH, thereby producing K2SO3. What is the maximum mass of SO2 that could be
removed by 1,000. liters of the KOH solution? 9456
   (A) 4.0 kg
   (B) 8.0 kg
   (C) 16 kg
   (D) 20. kg
   (E) 40. kg




21. Barium sulfate is LEAST soluble in a 0.01-molar solution of which of the following?
9465
   (A) Al2(SO4)3
   (B) (NH4)2SO4
   (C) Na2SO4
    (D) NH3
    (E) BaCl2


22. What is the pH of a 1.0 x 10-2-molar solution of HCN? (For HCN, Ka = 4.0 x 10-10.)
9466
    (A) 10
    (B) Between 7 and 10
    (C) 7
    (D) Between 4 and 7
    (E) 4




23. Correct procedures for a titration include which of the following?

I. Draining a pipet by touching the tip to the side of the container used for the titration
II. Rinsing the buret with distilled water just before filling it with the liquid to be titrated
III. Swirling the solution frequently during the titration                       9469
    (A) I only
    (B) II only
    (C) I and III only
    (D) II and III only
    (E) I, II, and III


24. To determine the molar mass of a solid monoprotic acid, a student titrated a weighed
sample of the acid with standardized aqueous NaOH. Which of the following could
explain why the student obtained a molar mass that was too large?           9470

I. Failure to rinse all acid from the weighing paper into the titration vessel
II. Addition of more water than was needed to dissolve the acid
III. Addition of some base beyond the equivalence point
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II, and III


25. A solution of calcium hypochlorite, a common additive to swimming-pool water, is
9474
    (A) basic because of the hydrolysis of the OCl- ion
    (B) basic because Ca(OH)2 is a weak and insoluble base
    (C) neutral if the concentration is kept below 0.1 molar
      (D) acidic because of the hydrolysis of the Ca2+ ions
      (E) acidic because the acid HOCl is formed


Questions 26-29 refer to aqueous solutions containing 1:1 mole ratios of the following
pairs of substances. Assume all concentrations are 1 M. 99-9-12
      (A) NH3 and NH4Cl
      (B) H3PO4 and NaH2PO4
      (C) HCl and NaCl
      (D) NaOH and NH3
      (E) NH3 and HC2H3O2
26. The solution with the lowest pH
27. The most nearly neutral solution
28. A buffer at a pH > 8
29. A buffer at a pH < 6


30. A sample of 61.8 g of H3BO3, a weak acid is dissolved in 1,000 g of water to make a
1.0-molal solution. Which of the following would be the best procedure to determine to
molarity of the solution? (Assume no additional information is available.) 9943
      (A) Titration of the solution with standard acid
      (B) Measurement of the pH with a pH meter
      (C) Determination of the boiling point of the solution
      (D) Measurement of the total volume of the solution
      (E) Measurement of the specific heat of the solution


31. In liquid ammonia, the reaction represented above occurs. In the reaction, NH4+ acts
         as
                                                           0222
(A)      a catalyst.
(B)      both an acid and a base.
(C)      the conjugate acid of NH3.
(D)      the reducing agent.
(E)      the oxidizing agent.


32.               HCO3-(aq) + OH-(aq)  H2O(l) + CO32-(aq)           ΔH = -41.4 kJ

         When the reaction represented by the equation above is at equilibrium at 1 atm
                                   2
                               [CO 3- ]
         and 25 oC, the ratio        -
                                        can be increased by doing which of the following?
                              [HCO 3 ]
                0237

(A)      Decreasing the temperature
(B)    Adding acid
(C)    Adding a catalyst
(D)    Diluting the solution with distilled water
(E)    Bubbling neon gas through the solution




Questions 33-34                                      02-33-34

The graph below shows the titration curve that results when 100. mL of 0.0250 M acetic
acid is titrated with 0.100 M NaOH.




33.    Which of the following indicators is the best choice for this titration?   0233

                                              pH Range of
              Indicator                       Color Change
(A)           Methyl Orange                   3.2-4.4
(B)           Methyl Red                      4.8-6.0
(C)           Bromothymol blue                6.1-7.6
(D)           Phenolphthalein                 8.2-10.0
(E)            Alizarin                     11.0-12.4


34.    Which part of the curve corresponds to the optimum buffer action for the acetic
       acid / acetate ion pair?                    0234

(A)    Point V
(B)    Point X
(C)    Point Z
(D)    Along all of section WY
(E)    Along all of section YZ


35. How can 100. mL of sodium hydroxide solution with a pH of 13.00 be converted to a
      sodium hydroxide solution with a pH of 12.00?                           02-61

(A)    By diluting the solution with distilled water to a total volume of 108 mL
(B)    By diluting the solution with distilled water to a total volume of 200 mL
(C)    By diluting the solution with distilled water to a total volume of 1.0 L
(D)    By adding 100. mL of 0.10 M HCl.
(E)    By adding 100. mL of 0.10 M NaOH.

36. Mixtures that would be considered buffers include which of the following?      0263

       I.      0.10 M HCl and 0.10 M NaCl
       II.     0.10 M HF and 0.10 M NaF
       III     0.10 M HBr and 0.10 M NaBr

(A)    I only
(B)    II only
(C)    III only
(D)    I and II
(E)    II and III

37.    Ascorbic acid, H2C6H6O6(s), is a diprotic acid with K1 = 7.9 × 10-5 and K2 = 1.6 ×
       10-12. In a 0.005 M aqueous solution of ascorbic acid, which of the following
       species is present in the lowest concentration? 0264

(A)    H2O(l)
(B)    H3O+(aq)
(C)    H2C6H6O6(aq)
(D)    HC6H6O6-(aq)
(E)    C6H6O62-(aq)
38. In a saturated solution of Zn(OH)2 at 25 oC, the value of [OH-] is 2.0 × 10-6 M. What
        is the value of the solubility-product constant, Ksp, for Zn(OH)2 at 25 oC?
        0275

(A)    4.0 × 10-18
(B)    8.0 × 10-18
(C)    1.6 × 10-17
(D)    4.0 × 10-12
(E)    2.0 × 10-6


1e 2a 3d 4c 5d 6e 7d 8d 9a 10e 11d 12a 13d 14b 15d 16e 17b 18b 19e 20b

21a 22d 23c 24a 25a 26c 27e 28a 29b 30d 31c 32a 33d 34a 35c 36b 37e 38a

								
To top