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Unit 11 - Acids, Bases and Salts Chemistry
Accelerated Chemistry I
Define each of the following:
1. Acidic hydrogens
2. Binary acids
3. Oxyacids
4. Carboxylic acid
5. Amines
Name the following acids and bases.
______________________ 6. HNO3
______________________ 10. H3PO3
______________________ 7. HClO
______________________ 11. KOH
______________________ 8. H2SO4
______________________ 12. H2CO3
______________________ 9. HC2H3O2
______________________ 13. CH3NH2
Acid and Base Definitions
1. Identify each of the following as an acid or a base and write a chemical equation showing how it is an acid
or a base according to the Arrhenius definition. The first one is done for you.
a. HNO3(aq) – acid, HNO3 (aq)  H+ (aq) + NO3 – (aq)
b. KOH(aq)
c. HC2H3O2(aq)
d. Sr(OH)2
2. Identify each of the following as an acid or a base and write a chemical equation showing how it is an acid
or a base according to the Arrhenius definition.
a. NaOH(aq)
b. HBr(aq)
c. Sr(OH)2(aq)
d. H2SO4(aq)
3. For each of the following, identify the Bronsted-acid, the Bronsted-Lowry base, the conjugate acid, and the
conjugate base.
a. HBr(aq) + H2O(l) → H3O+(aq) + Br-(aq)
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b. NH3(aq) + H2O(l)  NH4+(aq) + OH-(aq)
c. HNO3(aq) + H2O(l) → H3O+(aq) + NO3- (aq)
d. C5H5N(aq) + H2O(l)  C5H5NH+(aq) + OH-(aq)
4. Which of the following are conjugate acid-base pairs?
a. NH3, NH4+
b. HCl, HBr
c. C2H3O2-, HC2H3O2
d. HCO3-, NO35. Which of the following are conjugate acid-base pairs?
a. HI, Ib. HCHO2, SO42c. PO43-, HPO42d. CO32-, HCl
6. Write the dissociation equation for each of the following acids or bases in water. Identify the conjugate
acid/base pairs. The first one is done for you:
a. HI(aq) + H2O(l)  H3O+(aq) + I-(aq)
Acid
base
conj acid conj base
b. CH3NH2
c. CO32d. H2CO3
7. Write the dissociation equation for each of the following acids or bases in aqueous solution. Identify the
conjugate acid/base pairs.
a. HCl
b. H2SO3
c. HClO
d. HCHO2
e. HF
8. Write the formula for the conjugate acid of each of the following bases.
a. CH3NH2
b. C5H5N
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c. Cld. F-
Strong Acids and Strong Bases REVIEW!!
Strong Acids
StrongBases
Hydrochloric, HCl
All Alkali metal hydroxides – LiOH, KOH, NaOH, etc.
Hydrobromic, HBr
Ca(OH)2
Hydroiodic, HI
Ba(OH)2
Perchloric, HClO4
Sr(OH)2
Chloric, HClO3
Sulfuric, H2SO4
Nitric, HNO3
* If an acid or base is not listed in the above list it can be considered weak.
* Keep in mind that conjugate acids/bases of STRONG acids/bases are considered WEAK.
* Keep in mind that conjugate acids/bases of WEAK acids/bases are considered STRONG.
Strong and Weak Acids and Bases
9. Classify each of the following acids as strong or weak. Write its conjugate base and classify it as weak or
strong. The first one is done for you:
a. HCHO2 – weak acid
CHO2 - strong base
b. HCl
c. HNO3
d. H2CO3
e. HC2H3O2
f. H3PO3
Acide/Base Equilibria: Ka, Kb, Kw
10. Butylamine (C4H9NH2) is a weak base. If the initial concentration of butylamine is 0.230 M and
the equilibrium concentration of hydroxide ion is 8.6 x 10
Answ: 3.2x10
-10
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M, calculate the Kb for butylamine.
3
11. If 0.690 mol of a weak acid is dissolved in water to a total volume of 0.75 L. At equilibrium the
concentration of hydronium ion is 0.0024 M, calculate the Ka for this acid. Answ: 6.3x10-6
12. Phenol (C6H5OH), commonly called carbolic acid, is a weak organic acid (Ka = 1.3 x 10-10). First,
write the dissociation equation. If you dissolve 0.195 g of the acid in enough water to make 125
mL of solution, what is the equilibrium hydronium ion concentration? What is the pH of the
solution? Answ: [H3O+]=1.50x10-6M, pH = 5.83
13. The weak base methylamine, CH3NH2, has Kb = 4.2x10-4. First, write the dissociation equation.
Calculate the equilibrium hydroxide ion concentration in a 0.25 M solution of the base. What are
the pH and pOH of the solution? Answ: [OH-]=1.0x10-2M, pH = 2
14. What is the hydronium ion concentration in 0.1 M ammonia if hydroxide ion concentration = 1.26
–3
x 10
M? Is ammonia acidic, basic, or neutral? Answ: [H3O+]=7.94x10-12M, pH = 11, basic
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15. What is the hydroxide ion concentration in butter if hydronium ion concentration = 6.00 x 10
Is butter acidic, basic, or neutral? Answ: [OH-]=1.67x10-8M, pH = 6.22, slightly acidic
–7
M?
16. During the course of the day, human saliva varies between acidic and basic. What is the
–8
hydronium ion concentration in saliva if hydroxide ion concentration = 3.16 x 10 M? Is this
sample of saliva acidic, basic, or neutral? Answ: [H3O+]=3.16x10-7M, pH = 6.50, slightly acidic
17. Determine [H3O+] in each of the following acid solutions. For weak acids, give what [H3O+] is less than.
The first one is done for you.
a. 2.5 M HI - [H3O+] is 2.5 M
b. 1.2 M HClO2 - [H3O+] is less than 1.2 M
c. 0.25 M HClO3
d. 2.25 M HNO2
18. Classify each of the following bases as strong or weak.
a. C5H5N
b. NaOH
c. Ba(OH)2
d. CO3
2-
19. Determine [OH-] in each of the following base solutions. For weak bases, give what [OH-] is less than.
a. 0.88 M NaOH
b. 0.88 M NH3
c. 0.88 M Sr(OH)2
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d. 1.55 M KOH
pH and pOH Calcualtions
20. Calculate [OH-] given [H3O+] in each of the following aqueous solutions and classify the solution as acidic
or basic.
a. [H3O+] = 1.5 x 10-9M
b. [H3O+] = 9.3 x 10-9M
c. [H3O+] = 2.2 x 10-6M
d. [H3O+] = 7.4 x 10-4M
21. Calculate the pH of each of the following solutions.
a. [H3O+] = 1.7 x 10-8 M
b. [H3O+] = 1.0 x 10-7M
c. [H3O+] = 2.2 x 10-6 M
d. [H3O+] = 7.4 x 10-4 M
22. Calculate [H3O+] for each of the following solutions.
a. pH = 8.55
b. pH = 11.23
c. pH = 2.87
d. pH = 1.22
23. Calculate [OH-] for each of the following solutions.
a. pH = 4.25
b. pH = 12.53
c. pH = 1.50
d. pH = 8.25
24. Calculate the pH of each of the following solutions:
a. 0.0155M HBr
b. 1.28 x 10-3M KOH
c. 1.89 x 10-3 M HNO3
d. 1.54 x 10-4 M Sr(OH)2
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25. Calculate the pOH of each of the following solutions:
a. 1.34 x 10-3 M HClO4
b. 0.0211M NaOH
c. 0.0109 M HBr
d. 7.02 x 10-5 M Ba(OH)2
Acid-Base Reactions
26. Write neutralization reactions for each of the following acids and bases.
a. HI(aq) and NaOH(aq)
b. HBr(aq) and KOH(aq)
c. HNO3(aq) and Ba(OH)2(aq)
d. HClO4(aq) and Sr(OH)2(aq)
27. Write neutralization reactions for each of the following acids and bases.
a. HF(aq)and Ba(OH)2(aq)
b. HClO4(aq) and NaOH(aq)
c. HBr(aq) and Ca(OH)2(aq)
d. HCl(aq) and KOH(aq)
28. Explain how a neutralization reaction is different from a dissociation equation. Provide an example of each.
Acid-Base Titrations
29. Four solutions of unknown HCl concentration are titrated with solutions of NaOH. The following table lists
the volume of each unknown HCl solution, the volume of NaOH solution required to reach the endpoint,
and the concentration of each NaOH solution. Calculate the concentration (in M) of the unknown HCl
solution in each case.
HCl Volume (mL)
(a) 25.00 mL
(b) 15.00mL
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[HCl] (M)
NaOH Volume (mL)
28.44 mL
21.22 mL
[NaOH] (M)
0.1231 M
0.0972 M
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30. Four solutions of unknown NaOH concentration are titrated with solutions of HCl. The following table lists
the volume of each unknown NaOH Solution, the volume of HCl solution required to reach the endpoint,
and the concentration of each HCl solution. Calculate the concentration (in M) of the unknown NaOH
solution in each case.
NaOH Volume (mL)
(a) 5.00 mL
(b) 15.00 mL
[NaOH] (M)
HCl Volume (mL)
9.77 mL
11.34mL
[HCl] (M)
0.1599M
0.1311M
31. A 25.00-mL sample of an H2SO4 solution of unknown concentration is titrated with a 0.1328 M KOH
solution. A volume of 38.33 mL of KOH was required to reach the endpoint. What is the concentration of
the unknown H2SO4 solution? Answ: 0.1018 M
32. A 5.00-mL sample of an H3PO4solution of unknown concentration is titrated with a 0.1221M NaOH
solution. A volume of 5.99mL of the NaOH solution was required to reach the endpoint. What is the
concentration of the unknown H3PO4 solution? Answ: 0.0488 M
33. What volume in milliliters of a 0.101 M NaOH solution is required to reach the endpoint in the complete
titration of a 10.0-mL sample of 0.138 M H2SO4? Answ: 27.3 mL
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34. What volume in milliliters of 0.0992M NaOH solution is required to reach the endpoint in the complete
titration of a 15.0-mL sample of 0.107 M H3PO4? Answ: 48.6 mL
Acid-Base Hydrolysis
Hydrolysis occurs when certain salts dissolve in water to form solutions that have acidic or basic properties. A
rule for predicting the properties of solutions of salts is based upon the concept of strong acids and strong bases
in the Bronsted-Lowry sense. The rules are summarized in the table below:
Salt formed from
Water solution exhibits
Example
Strong acid + strong base
no hydrolysis - neutral solutions
Strong acid + weak base
hydrolysis to form acidic solution
NH4SO4
Weak acid + strong base
hydrolysis to form basic solution
Na2CO3
Weak acid + weak base
Must use Ka and Kb to determine
Pb(C2H3O2)2
KCl
The commonly used strong acids are hydrochloric, nitric and sulfuric. The commonly used strong bases are
sodium hydroxide, potassium hydroxide, and calcium hydroxide.
Predict the hydrolysis effect of each of the following salts. For each answer write acidic, basic neutral or need
Ka and Kb.
______________________ 1. Na3PO4
______________________ 2. Na2SO4
______________________ 3. NaC2H3O2
______________________ 4. NH4NO3
______________________ 5. NH4Cl
______________________ 6. Fe3(PO4)2
______________________ 7. Ca(NO3)2
______________________ 8. KC2H3O2
______________________ 9. CuSO4
______________________ 10. Al(NO3)3
______________________ 11. NaCl
______________________ 12. K2CO3
Cummulative
35. A 0.125-g sample of a monoprotic acid of unknown molar mass is dissolved in water and titrated with
0.1003 M NaOH. The endpoint is reached after adding 20.77 mL of base. What is the molar mass of the
unknown acid? Answ: 60.0 g/mol
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36. A 0.1O5-g sample of a diprotic acid of unknown molar mass is dissolved in water and titrated with 0.1288
M NaOH. The endpoint is reached after adding 15.2 mL of base. What is the molar mass of the unknown
acid? Answ: 107 g/mol
37. Antacids, such as milk of magnesia, are often taken to reduce the discomfort of acid stomach or heartburn.
The recommended dose of milk of magnesia is 1 teaspoon, which contains 400 mg of Mg(OH)2. What
volume of HCl solution with a pH of 1.1 can be neutralized by 1 dose of milk of magnesia? (Assume two
significant figures in your calculations.) Answ: 170 mL
38. For each of the following strong base solutions, determine [OH-], [H3O+], and pH.
a. 0.15M NaOH
b. 8.7 x 10-5M KOH
39. For each of the following weak base solutions, determine [OH-], [H3O+], and pH.
a. Al(OH)3 (Ksp = 3.0x10-34)
b. Cd(OH)2 (Ksp = 7.2x10-15)
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40. Methylamine, CH3NH2, is a weak base. If the pH of a 0.065 M solution of the amine is 11.70,
what is the value of Kb? Answ: 3.8x10-4M
41. A popular classroom demonstration consists of filing notches into a new penny and soaking the penny in
hydrochloric acid overnight. Since new pennies are made of zinc coated with copper, and since hydrochloric
acid dissolves zinc and not copper, the inside of the penny is dissolved by the acid, while the outer copper
shell remains. Suppose the penny contains 2.5 g of zinc and is soaked in 20.0mL of 6.0M HCl. Calculate the
concentration of the HCl solution after all of the zinc has dissolved. Calculate the pH and pOH of the
resulting solution. Answ: [HCl] = 2 M, pH = -0.3, pOH = 14.3
42. What is the pH of a solution formed by mixing 125.0 mL of 0.0250 M HCl with 75.0 mL of 0.0500M
NaOH? Answ: pH = 11.5
43. Calculate the hydroxide ion concentration and the pH of the solution that results when 22.0 mL of 0.15 M of
acetic acid is mixed with 22.0 mL of 0.15 M NaOH. (Remember salt hydrolysis. What type of salt is formed
from the reaction of acetic acid with NaOH? What side-reaction will occur as a result of this salt dissolving
in water? Kb: C2H3O2- = 5.6x10-10) Answ: [OH-]=6.5x10-6M, pOH = 5.2, pH = 8.8 (The side reaction is the
acetate conj base reacting with water!)
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44. How many H+ (or H3O+) ions are present in one drop (0.050 mL) of pure water at 25°C? Answ:
[H3O+]=1.x10-7M, 3.0x1012 ions
60. You are titrating a 50.0 mL sample of hydrochloric acid with 0.250 M potassium hydroxide. After you have
already added 42.3 mL of the potassium hydroxide you realize that you forgot to add the phenolphthalein
indicator. When you add the indicator, the solution turns bright pink indicating that you have already
missed the end point. You decide to “back-titrate” by adding 0.100 M nitric acid. The solution turns
colorless after an addition of 10.1 mL of the nitric acid. What is the concentration of the original solution of
hydrochloric acid? Answ: 0.192 M
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