Northrup's Chem 112 Section TTU General Chemistry

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Chem 112 - Quiz 5A - Spring, 1997
Chapter 18: Ionic Equilibria I, Acids and Bases

1. What volume of 0.050 M NaOH(aq) will exactly neutralize 100.0 mL of 0.075 M HBr solution?

a) 100.0 mL
b) 7.5 mL
c) 6.6 x 10-3 mL
d) 150 mL
e) 120 mL

2. What volume of 0.200 M H2SO4(aq) would exactly neutralize 2.00 L of 1.0 x 10-3 M Al(OH)3?

a) 6.7 mL
b) 10 mL
c) 15 mL
d) 1.00 L
e) 75 mL

3. What is the hydroxide concentration in a solution which results from pouring 100 mL of 0.010 M HCl together with 200 mL of 0.030M Ca(OH)2(aq) solution? Assume that the liquid volumes are additive.

a) 0.020 M
b) 0.0183 M
c) 0.0367 M
d) 0.060 M
e) 0.030 M

4. What reagent would be the best choice for a primary standard to standardize a solution of KOH of unknown concentration?

a) KHP (potassium hydrogen phthalate)
b) sodium carbonate
c) sodium hydroxide
d) HCl
e) KCl

5. In standardizing an HCl solution of unknown concentration, 21.50 mL of HCl solution are found to reach the endpoint in a titration with 4.086 g of Na2CO3. (MW = 106.0 g/mol) What is the molarity of the HCl solution?

a) 1.79 M
b) 3.58 M
c) 0.896 M
d) 3.6 x 10-3 M

6. What is the equivalent weight of Ca(OH)2?

a) 24.7 g/eq
b) 74.1 g/eq
c) 148.2 g/eq
d) 37 g/eq

7. How many equivalents are in 1 mole of H3PO4?

a) 0.33
b) 1
c) 3
d) 98
e) 33

8. How many equivalents are in 1.00 gram of H2SO4? (MW = 98 g/mol)

a) 0.020
b) 0.010
c) 0.0051
d) 98
e) 49

9. What is the normality of 12.0 M H2SO4?

a) 3.0 N
b) 6.0 N
c) 12.0 N
d) 4.0 N
e) 24.0 N

10. What is the molarity of 1.0 N HI?

a) 7.8 x 10-3
b) 128
c) 1.0
d) 2.0

11. Suppose 9.8 grams of H2SO4 (MW = 98 g/mol) are dissolved in 250.0 mL of aqueous solution. What is the Normality of H2SO4 in the solution?

a) 19.6 N
b) 0.40 N
c) 0.20 N
d) 4.9 N
e) 0.80 N

12. What volume of 3.0 N H3PO4 would exactly neutralize 250.0 mL of aqueous 2.0 N NaOH?

a) 375 mL
b) 166.7 mL
c) 250.0 mL
d) 45 mL

13. What is the hydronium ion concentration in a solution which is 0.10 M HNO3(aq)?

a) 0.30 M
b) 0.10 M
c) 6.7 x 10-3 M
d) 1.0 x 10-7 M
e) 2.1 x 10-2 M

14. What is the hydroxide ion concentration in 1.0 M HBr?

a) 1.0 M
b) 1.0 x 10-13 M
c) 1.0 x 10-14 M
d) 1.0 x 10-7 M

15. What is the pH of 1.0 x 10-3 M aqueous HClO4?

a) 10-7
b) -3.0
c) 0.0
d) 3.0
e) 1.0

16. What is the hydronium ion concentration in a solution which has [OH-] = 1.0 x 10- 2 M?

a) 1.0 x 10-12 M
b) 1.0 x 10-2 M
c) 1.0 x 10-16 M
d) 12
e) 1.0 x 10-7 M

17. Identify the INCORRECT statement:

a) As the pH increases the hydroxide ion decreases.
b) As the pH increases the hydronium ion concentration decreases.
c) As the pH increases the Kw of water remains the same.
d) As the pH increases the product [H3O+][OH-] remains constant.
e) As the pH increases the solution becomes less acidic and more alkaline.

18. Identify the most INCORRECT statement:

a) Blood has a pH near 7.
b) Stomach juices have a pH near 2.
c) Vinegar has a pH near 10.
d) Glass cleaner has a pH near 12.
e) Drano has a pH near 14.

19. Which acid is the weakest acid? Refer to the table of acids given.

a) HCN
b) 3 HNO2
c) HAc
d) HOCl
e) HF

20. What is the Ka of HNO2(aq)? Refer to the table of acids given.

a) -0.525
b) 3.35
c) 0.525
d) 4.5 x 10-4
e) 1.8 x 10-5

21. What is the pH of a 0.10 M solution of HF in water? The Ka = 7.2 x 10- 4.

a) -2.07
b) 8.5 x 10-3
c) 0.10
d) 3.14
e) 2.1

22. What is the percent ionization of the acid in Problem #21?

a) 100%
b) 8.5%
c) 0.11%
d) 0.0011%
e) 0.08%

23. What is the pH of a 0.20 M aqueous solution of the base methylamine, CH3NH2? Kb = 5.0 x 10-4.

a) 2.0
b) 12.0
c) 16.0
d) 10.0
e) 0.01

24. A buffer solution is prepared by the addition of 20.0 grams of HF and 21.0 grams of NaF to enough water to make 1.000 L of solution. The Ka of HF is 7.2 x 10-4. What is the pH of this solution?

a) 3.44
b) 3.14
c) 2.84
d) 7.0
e)2.4

25. Which of the following pairs of compounds dissolved together in aqueous solution would NOT make a good buffer solution?

a) HNO3/NaNO3
b) H3PO4/NaH2PO4
c) H2CO3/KHCO3
d) HCN/KCN

26. A buffer solution is 0.10 M HAc (acetic acid) and 0.10 M NaAc (sodium acetate) and we have 1.000 Liter of it. What is the pH after 0.010 moles of HCl are added to this solution?

a) -2.0
b) 4.74
c) 4.82
d) 2.0
e) 4.65

27. We desire to make a buffer solution with a pH of 9.2. Which combination of compounds would be the best to use? Refer to the table of bases given.

a) HAc/NaAc
b) NH3/NH4Cl
c) HCl/NaCl
d) pyridine/pyridine chloride

28. A solution is prepared which is 1.0 M acetic acid. What would happen to the pH of this solution if potassium acetate were added to the solution?

a) pH would go up
b) pH would go down
c) would not affect the pH

29. A buffer solution has a pH = 5.5. What is the [H3O+] concentration?

a) 5.5 M
b) 3.16 x 10-6 M
c) 3.2 x 105 M
d) 0.74 M
e) 3.2 x 10-3 M
 

       ACID       pKa        Ka
       --------------------------------
       HF        3.14     7.2 x 10-4
       HNO2      3.35     --------
       HAc       4.74     1.8 x 10-5
       HOC       7.45     3.5 x 10-8
       HCN       9.4      4.0 x 10-10



       BASE              pKb           Kb
       ---------------------------------------
       ammonia          4.74     1.8 x 10-5
       methylamine      3.30     5.0 x 10-4
       dimethylamine    3.13     7.4 x 10-4
       trimethylamine   4.13     7.4 x 10-5
       pyridine         8.82     1.5 x 10-9

KEY

1)d 2)c 3)c 4)a 5)b 6)d 7)c 8)a 9)e 10)c 11)e 12)b 13)b 14)c 15)d 16)a 17)a 18)c 19)a 20)d 21)e 22)b 23)b 24)c 25)a 26)e 27)b 28)a 29)b
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