KEY
Sample Questions for Chapter 14: Acids and Bases
14.1 Acids and Bases
1.
(Read pgs. 442-446 in the chemistry textbook)
(a) What does it mean to say a solid substance has dissolved in water?
the individual particles of the solid have been completely
surrounded by water molecules
(b) What does it mean for a chemical to dissociate (ionize) in aqueous solution?
some of the solid that dissolves produces ions
2.
(a) What is an electrolyte?
substances which will produce ions when they dissolve - the
resulting solution will conduct an electric current
b) What are strong electrolytes?
substances for which 100% of the particles ionize in aqueous
solution - the resulting solution is a strong conductor of
electricity
(c) What are weak electrolytes?
substances for which less than 100 % of the particles will
ionize in aqueous solution - the resulting solution is a weak
conductor of electricity
(d) what is a nonelectrolyte?
a substance which dissolves in water but produces no ions the resulting solution is a nonconductor of elctricity
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3.
(a) Fill in the following table of electrolytes:
Summary of Electrolytic Behavior of Common Soluble Ionic and Molecular Compounds
Compound
Strong Electrolyte
Weak Electrolyte
Nonelectrolyte
Ionic
All
None
None
Molecular
Strong Acids
Weak Acids
Weak Bases
All other
compounds
(b) What happens if an ionic substance is insoluble in water?
it is considered a weak electrolyte, b/c some miniscule amount
WILL dissolve and ionize 100% .....but, b/c such a small amount
dissolves there there will not be many ions in the solution
4. Identify each of the following as a strong, weak, or nonelectrolyte based on their chemical formulas.
i.
CO2
non
vi.
NH4CH3COOH
strong
ii.
KNO3
strong
vii.
LiBr
strong
iii.
C2H6
non
viii.
XeF2
non
iv.
Mg(OH)2
weak
ix.
PbSO4
weak
v.
NaCl
strong
x.
Ca3(PO4)2
weak
5. Identify the non-, strong, and weak electrolytic solutions below. Explain your choices.
strong electrolyte
100% ionized
weak electrolyte
< 100% ionized
nonelectrolyte
no ions
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6.
(a) What is the hydronium ion?
it is a water molecule which has an extra hydrogen atom
(b) What is the symbol for the hydronium ion?
H3O+
7.
usually shortened to just H+
(a) What is the hydroxide ion?
it is a water molecule which has lost one of its electrons
(b) What is the symbol for the hydroxide ion?
OH −
8. What is an acid?
a substance that dissociates in water and causes an increase in the
concentration of hydronium ion, [H+]*, of the aqueous solution
*NOTE: brackets indicate concentration in molarity, thus [H+] means
the concentration of H+ ion in moles per liter
9. What is a base?
a substance that dissociates in water and causes an increase in the
concentration of hydroxide ion, [OH−]
10. The table of electrolytes from Question 3(a) identifies strong acids as strong electrolytes. What are the
strong acids?
1. HCl
hydrochloric acid
5. HClO3
chloric acid
2. HBr
hydrobromic acid
6. HClO4
perchloric acid
3. HI
hydroiodic acid
7. H2SO4
sulfuric acid
4. HNO3
nitric acid
ALL other acids are weak acids - meaning
they are weak electrolytes
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11. Write a dissociation equation for the following strong and weak acids.
STRONG ACIDS:
HCl(aq) → H+(aq) + Cl−(aq)
(a) HCl(aq)
(b) HNO3(aq)
HNO3(aq) → H+(aq) + NO3− (aq)
(c) H2SO4(aq)
H2SO4(aq) → 2H+(aq) + SO42− (aq)
WEAK ACIDS:
HF(aq)
(a) HF(aq)
H+(aq) + F−(aq)
(b) HNO2(aq)
HNO2(aq)
H+(aq) + NO2− (aq)
(c) H2SO3(aq)
H2SO3(aq)
2H+(aq) + SO32− (aq)
a double arrow is used because weak electrolytes do not stay
dissolved......the undissolved part is always in equilibrium with the
dissolved part
12. All the strong bases are ionic compounds and, therefore, strong electrolytes. What are the strong bases?
1. LiOH
lithium hydroxide
2. NaOH
sodium hydroxide
3. KOH
potassium hydroxide
4. RbOH
rubidium hydroxide
5. CsOH
cesium hydroxide
6. Ca(OH)2
calcium hydroxide
7. Sr(OH)2
strontium hydroxide
8. Ba(OH)2
barium hydroxide
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13. Write a dissociation equation for the following strong and weak Bases.
STRONG BASES:
LiOH(s) → Li+(aq) + OH−(aq)
(a) LiOH(s)
Ca(OH)2(s) → Ca2+(aq) + 2 OH− (aq)
(b) Ca(OH)2(s)
WEAK BASES:
(a) Mg(OH)2(s)
(b) Sr(OH)3(s)
Mg(OH)2(s)
Mg2+(aq) + 2 OH−(aq)
Sr(OH)3(s)
Sr3+(aq) + 3 OH−(aq)
14. The ammonium polyatomic ion, NH4+(aq), dissociates weakly to increase the [H+] in aqueous solution.
Write an equation to show the dissociation of the ammonium polyatomic ion.
NH4+(aq)
NH3(aq) + H+(aq)
acidic solution
15. The ammonia molecule, NH3(aq), reacts in an equilibrium reaction with water to increase the [OH−] in
aqueous solution. Write an equation to show the dissociation of the ammonia molecule.
NH3(aq) + H2O(l)
NH4+(aq) + OH−(aq)
basic solution
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ACID NOMENCLATURE
16.
(a) What is a binary acid?
an acid composed of hydrogen and one other element – the 2nd
element will be a nonmetal
(b) How are binary acids named?
1 = ALWAYS begin with the word “hydro-“
st
2nd = the ending of the name of the 2nd element is changed to “ic”
17. What are the common binary acids?
 HF
= hydrofluoric acid
 HCl
= hydrochloric acid
 HBr
= hydrobromic acid
 HI
= hydroiodic acid
 H 2S
= hydrosulfuric acid
 H 2O
= hydroxylic acid (A.K.A. – water )
 H 3P
= hydrophosphoric acid
 HCN*
= hydrocyanic acid
*NOTE: this is an exception b/c it is composed of 3 elements
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18.
(a) What is an oxy-acids?
an acid composed of a polyatomic ion to which hydrogen has been
attached
(b) How are oxy-acids named?
they are named after the polyatomic ion – but, the ending of the name
is changed to “ic”
19. What are the “trendsetter” oxy-acids?
Polyatomic
Anion
NO3─
Polyatomic
Name
nitrate
Acid
Name
Nitric Acid
Chemical
Formula
HNO3
CO32─
carbonate
Carbonic
H2CO3
SO42─
sulfate
Sulfuric Acid
H2SO4
PO43─
phosphate
Phosphoric Acid
H3PO4
ClO3─
chlorate
Chloric Acid
HClO3
CrO42─
chromate
Chromic Acid
H2CrO4
Cr2O72─
dichromate
Dichromic Acid
H2Cr2O7
MnO4─
permanganate
permanganic Acid
HMnO4
CNO─
cyanate
Cyanic Acid
HCNO*
 *NOTE: this is an exception b/c it is composed of 4 elements
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20. How can the “Trendsetter” oxy-acids be changed?
EXAMPLE
Change Made
Change in Name
Name
(+) 1 O atom
prefix w/ “per”
perchloric
HClO4
Chloric
HClO3
TRENDSETTER
Formula
( ̶ ) 1 Ox atom
change “ic” to “ous”
chlorous
HClO2
( ̶ ) 2 Ox atoms
prefix with “hypo”
hypochlorous
HClO
21. Practice changing the name or formula of the trendsetters
Acid
Name
a)
phosphorous acid
Chemical
Formula
H3PO3
b) sulfurous acid
H2SO3
c) nitrous acid
HNO2
d)
hypophosphorous acid
H3PO2
e)
carbonous acid
H3CO2
f) pernitric acid
HNO4
g) hyposulfurous acid
H2SO2
h)
i)
chromous acid
Permanganous acid
H2CrO3
HMnO3
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PRACTICE QUESTIONS
22. Identify each of the following compounds as either and acid (A) or a base (B).
B
a. NaOH
A
d. H3PO4
A.
g. HNO3
B
j. Cu(OH)2
A
b. HCl
B
e. Al(OH)3
B
h. Ca(OH)2
B
k. Ba(OH)2
A
c. HCN
B
f. KOH
B
i. LiOH
A
l. HI
23. Write dissociation equations for each of the following acids or bases. Keep in mind whether or not it is a
strong or weak electrolyte.
1 of the 8 strong bases
Ba(OH)2 (s) → Ba2+(aq) + 2 OH-(aq)
a) barium hydroxide
b) nitrous acid
HNO3(aq)
c) aluminum hydroxide
Al(OH)3 (s)
a weak acid
H+(aq) + NO3─(aq)
a weak base
Al3+(aq) + 3 OH-(aq)
a weak base
Pb(OH)4(s)
Pb4+(aq) + 4 OH-(aq)
d) lead (IV) hydroxide
e) calcium hydroxide
Ca(OH)2(s)
a weak base
Ca2+(aq) + 2 OH-(aq)
1 of the 8 strong bases
LiOH (s) → Ba2+(aq) + OH-(aq)
f) lithium hydroxide
1 of the 7 strong acids
HClO3 (aq) → H+(aq) + ClO3-(aq)
g) chloric acid
h) copper (II) hydroxide
Cu(OH)2 (s)
a weak base
Cu2+(aq) + 2 OH-(aq)
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24. Name each of the following as an acid (A) or a base (B):
A
a. hydrochloric
A
e. sulfurous
B
j. potassium hydroxide
B
b. calcium hydroxide
B
f. lithium hydroxide
A
k. ammonium
A
c. carbonic
B
h. aluminum hydroxide
B
l. ammonia
B
d. nitric
A
i. hydrobromic
25. Write chemical formulas for each of the following and classify each as an acid (A) or a base (B):
Chemical
Formula
Acid/
Base
Mg(OH)2
B
a) magnesium hydroxide
HF
A
b) hydrofluoric
HNO3
A
c) nitric acid
LiOH
B
d) lithium hydroxide
NH4OH
B
e) ammonium hydroxide
H2CrO4
A
f) chromic acid
Ba(OH)2
B
g) barium hydroxide
26. Write the chemical formula for each of the following and then identify each of the following as a strong
electrolyte (SE), weak electrolyte (WE), or nonelecrtrolyte (NE). The solubility chart would be helpful!
Chemical
Formula
Electrolyte
(a) potassium hydroxide
KOH
SE
(b) sodium carbonate
Na2CO3
SE
(c) silver chloride
AgCl
WE
(d) dinitrogen pentoxide
N2O5
NE
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