Chemistry 30 Acid and Base Equilibrium
AB1 – Introduction to Acid and Base Theories
The Arrhenius theory
The modified Arrhenius theory
The Bronsted-Lowry theory
Conjugate Acid and base pairs
AB2 – Predicting Bronsted-Lowry Acid and Base
Reactions
Predicting BL reactions
Determine the extent (%) of the reaction
AB2.5 – Mono vs. Polyprotic Acids and Bases
Mono vs. polyprotic acids
Mono vs. polyprotic bases
AB3 – The Acid Ionization Constant (Ka)
Strong vs. weak acids
Strong acid calculations
The acid ionization constant (Ka) and weak acid
calculations
AB4 – The Base Dissociation Constant (Kb)
Strong vs. weak bases
Strong base calculations
The ionization of water constant (Kw)
The base dissociation constant (Kb) and weak
base calculations
AB5 – Ka and Kb vs. pH and pOH
pH and pOH
Ka vs. pH calculations
Kb vs. pOH calculations
AB6 – pH Curves and Indicators
Titration calculations
pH indicators
Strong vs. strong titration (pH) curves
Strong vs. weak titration (pH) curves
Polyprotic pH curves
AB7 – pH Buffer Solutions
Acid-base buffer solutions
How buffer solutions resist pH change.
AB1: Introduction to Acid and Base Theories (Conjugate Acid-Base Pairs)
For each of the following, predict the products, label each substance as Bronsted-Lowry acid or base,
and connect the conjugate pairs.
1. HSO3-(aq) + H2O(l) ⮀
2. NH3(aq) + H2O(l) ⮀
3. HF(aq) + HSO3-(aq) ⮀
4. H2SO3(aq) + HS-(aq) ⮀
5. HNO2(aq) + Cl-(aq) ⮀
6. CH3COOH(aq) + SO42-(aq) ⮀
7. H2S(aq) + NO2-(aq) ⮀
8. HCO3-(aq) + S2-(aq) ⮀
9. CO32-(aq) + H2O(l) ⮀
10. H2S(aq) + NH3(aq) ⮀
Extra Practice
11. H2SO4(aq) + H2O(l) 🡪
12. H2O(l) + H2O(l) ⮀
13. H2PO4-(aq) + H2O(l) ⮀
14. H2SO3(aq) + HS-(aq) ⮀
15. HPO42-(aq) + HCO3-(aq) ⮀
AB2: Predicting Bronsted-Lowry Reactions
For each of the following problems, indicate the species present, label each species as a
Brønsted-Lowry acid or base, write the reaction equation and predict the extent of reaction. Assume
only one proton is transferred.
1. Solutions of Na2SO3(aq) and HF(aq) are mixed in a beaker.
2. A solution of fertilizer NH 4NO3 and a solution of NaCH3COO are mixed.
3. Sodium benzoate is often used as a preservative. Write the equation for solid NaC6H5COO
dissolving in a solution of NaHSO4.
4. Sodium hydrogen carbonate is dissolved into a solution of sulfurous acid.
5. In solution the poisonous gas, H2S (that is found in natural “sour” gas) reacts with carbonate ions.
6. Sodium bicarbonate may be used in gripe water to neutralize excess stomach acid (HCl(aq)).
M/C and NR
1. Consider the reaction:
NaOH(aq) + CH3COOH(aq) ⮀ NaCH3COO(aq) + H2O(l)
a Bronsted-Lowry conjugate acid-base pair is:
a) CH3COOH(aq) and CH3COO-(aq)
b) CH3COOH(aq) and OH-(aq)
c) CH3COOH(aq) and H2O(l)
d) CH3COO-(aq) and H2O(l)
2. Which species is not amphiprotic?
c) NH4+(aq)
d) H2BO3-(aq)
a) H2O(l)
b) HS-(aq)
3. Manufacturers add alum, Al 2(SO4)3(s), during the production of paper. The aluminium ion was
hydrated and the following equilibrium was established:
Al(H2O)63+(aq) + H2O(l) ⮀ Al(OH)(H2O)52+(aq) + H3O+(aq)
1
2
3
4
In the forward rxn the Bronsted-Lowry acid is _____
In the forward rxn the Bronsted-Lowry base is _____
In the reverse rxn the Bronsted-Lowry acid is _____
In the reverse rxn the Bronsted-Lowry base is _____
4. In the acid-base reaction:
CH3COO-(aq) + HSO4-(aq) ⮀ CH3COOH(aq) + SO42-(aq),
a) products are favored
b) CH3COO-(aq) is an acid
c) SO42-(aq) is a proton donor
d) HSO4-(aq) and CH3COOH(aq) are a conjugate pairs
5. The conjugate acid of H2BO3-(aq) is…
a) HBO32-(aq)
b) BO33-(aq)
6. The hydrogen sulfide ion, HS-(aq) is…
c) H2O(l)
a) the conjugate acid of hydrosulfuric acid
b) an amphoteric substance
d) H3BO3(aq)
c) a weak acid and a strong base
d) a proton donor only
7. Equal volumes of two solutions that contain equal concentrations of HCO3-(aq) and H2PO4-(aq) are
mixed. In the reaction between H2PO4-(aq) and HCO3-(aq), the substance that acts primarily as an
acid is:
a) H2PO4-(aq)
b) HCO3-(aq)
c) HPO42-(aq)
d) H2O(l)
8. The Bronsted-Lowry equation that best represents the equilibrium in an aqueous solution of
ammonia is?
a) NH3(aq) ⮀ 3 H+(aq) + N3-(aq)
b) NH3(aq) + H2O(l) ⮀ NH4OH(aq)
c) NH3(aq) + H2O(l) ⮀ NH4+(aq) + OH-(aq)
d) NH3(aq) + H2O(l) ⮀ H3O+(aq) + NH2-(aq)
9. Consider the following reaction:
HSO4-(aq) + HCOO-(aq) ⮀ HCOOH(aq) + SO42-(aq)
1
2
3
4
For the favoured reaction, the acid and its conjugate base and then the base and its conjugate
acid, listed in that order are ____ ____ ____ ____ .
10. When citric acid combines with water in the mouth, one reaction that occurs is:
H3Ct(aq) + H2O(l) ⮀ H2Ct-(aq) + H3O+(aq)
The conjugate acid base pairs in this equation are
a) H3Ct(aq) / H3O+(aq) and H2O(l) / H2Ct-(aq) c) H3Ct(aq) / H2O(l) and H3O+(aq) / H2Ct-(aq)
b) H3Ct(aq) / HCt2-(aq) and H3O+(aq) / H2O(l) d) H3Ct(aq) / H2Ct-(aq) and H3O+(aq) / H2O(l)
11. Which of the Bronsted-Lowry acids listed below is stronger than H2S(aq)?
a) HSO3-(aq)
b) HCN(aq)
c) HCO3-(aq)
d) HCOOH(aq)
12. A reaction that favours the products is
a) HF(aq) + H2O(l) ⮀ H3O+(aq) + F-(aq)
b) HF(aq) + SO42-(aq) ⮀ HSO4-(aq) + F-(aq)
c) HSO4-(aq) + F-(aq) ⮀ HF(aq) + SO42-(aq)
d) H3BO3(aq) + F-(aq) ⮀ HF(aq) + H2BO3-(aq)
13. Which of the following substances is amphiprotic?
a) sodium sulfite
b) potassium hydrogen sulfite
c) calcium carbonate
d) sodium acetate
AB2.5: Mono vs. Polyprotic Acids and Bases
1. Complete the following table.
Acid
Substance
Ex. H2PO4-(aq)
Base
Strong/weak
Mono/poly
Strong/weak
Mono/poly
weak
poly
weak
mono
H2SO4(aq)
HCOO-(aq)
NH4+(aq)
HOOCCOOH(aq)
HBr(aq)
SO42-(aq)
NH3(aq)
HCN(aq)
HPO42-(aq)
AB3 – The Acid Ionization Constant (Ka)
1. In a 0.34 M of hypochlorous acid solution, a student found that the hydronium ion concentration was 1.7 x
10-4 mol/L. For this data, determine the experimental Ka for hypochlorous acid?
2. Determine the concentration of hydronium ions in a 0.18 mol/L solution of perchloric acid.
3. What is the cyanide ion concentration in a solution of 0.10 mol/L of hydrocyanic acid?
4. What is the ionization constant for citric acid if 1.0 mol of citric acid in 0.50 L of water produces a hydronium
ion concentration of 0.038 mol/L?
5. a) Determine the concentration of hydronium ions in a solution of 0.50 M benzoic acid.
Extra
b) Determine the concentration of hydronium ions when 0.50 mol of benzoic acid and 0.15 mol of aqueous
sodium benzoate are reacted in 1.0 L of water.
6. Determine the concentration of all species in a 0.30 mol/L solution of phosphoric acid.
M/C and NR
1. A student sampled four different acids, each at 0.10 mol/L, and she recorded these observations.
volume (mL) pH
conductivity
Acid I
50.2
4.50
poor
Acid II
40.5
3.25
poor
Acid III
20.7
1.50
good
Acid IV
15.0
5.50
poor
The acid that would be expected to have the lowest Ka value would be?
a) Acid I
b) Acid II
c) Acid III
d) Acid IV
c) H2SO3(aq)
d) H3PO4(aq)
2. Which species is not polyprotic?
a) HOOCCOOH(aq)
b) HCOOH(aq)
3. Use the information to answer the next question.
Acid
Ka Value
1 Phosphoric acid
6.9 x 10-3
2 Nitrous acid
5.6 x 10-4
3 Ethanoic acid
1.8 x 10-5
4 Hydrogen sulfate ion
1.0 x 10-2
Assuming that all of the above acids are 0.100 mol/L solutions, the acids ranked from strongest to weakest are:
_____ _____ _____ _____ .
4. Sulfuric acid is a…
a) monoprotic strong acid
b) monoprotic weak acid
c) diprotic strong acid
d) diprotic weak acid
5. If H2S(g) is released into the atmosphere, it dissolves in the atmosphere water to form hydrosulfuric acid.
The ionization of H2S(aq) can be represented by the equilibrium:
H2S(aq) + H2O(l) ⮀ HS-(aq) + H3O+(aq)
The Ka expression for this ionization is…
a) Ka =
[H2S(aq)]
[HS-(aq)] [H3O+(aq)]
c)
Ka = [HS-(aq)] [H3O+(aq)]
[H2S(aq)] [H2O(l)]
b)
[H2S(aq)] [H2O(l)]
[HS-(aq)] [H3O+(aq)]
d)
Ka =
Ka =
[HS-(aq)] [H3O+(aq)]
[H2S(aq)]
6. The [H3O+(aq)] in a 0.050 mol/L H 2S(aq) solution is?
a) 4.5 x 10-9 mol/L
b) 6.7 x 10-5 mol/L
c) 1.3 x 10-4 mol/L
d) 0.10 mol/L
c) 1.8 x 10-5 mol/L
d) 1.5 x 10-5 mol/L
7. The [H3O+(aq)] of the 0.83 mol/L CH 3COOH(aq) is?
a) 8.3 x 10-1 mol/L
b) 3.9 x 10-3 mol/L
8. Vinegar, an aqueous solution of acetic acid, is used to preserve and flavor food. Most of the vinegar used
for this purpose has an acid concentration of 0.83 mol/L.
The vinegar used in food has a…
a) [H3O+(aq)] equal to [CH3COO-(aq)]
b) [H3O+(aq)] greater than [CH3COOH(aq)]
c) [CH3COO-(aq)] equal to [CH3COOH(aq)]
d) [CH3COO-(aq)] greater than [H3O+(aq)]
AB4: Base Dissociation Constant (Kb)
1. Calculate the OH- concentration of a 0.10 mol/L solution of hydrazine, N2H4(aq), which has a Kb of 1.7 x 10-6.
2. The hydroxide concentration in a 0.16 mol/L solution of sodium propanoate (NaC 3H5O2) is found to be 1.1 X
10-5 mol/L. Calculate the base ionization constant for the propanoate ion.
3. Calculate the sodium ion concentration of a sodium oxalate solution with a base ionization constant of 1.7 x
10-7, and a hydroxide ion concentration of 2.9 x 10-6 mol/L.
4. Using the acid base table determine the Kb of the sulfite ion.
5. Calculate the hydroxide ion concentration of a 0.15 mol/L potassium acetate solution.
6. Morphine C17H10NO3, is a weak base and a powerful painkiller. It has a Kb value of 7.5 x 10-7. Calculate
the moles of morphine needed to make a 2.0 L solution with a hydroxide ion concentration of 3.5 x 10-4.
7. If the hydronium ion concentration of a solution is 3.2 x 10-6, what is the hydroxide ion concentration for that
solution?
Extra
8. A student dissolved 20.75 g of sodium carbonate in enough water to make a 0.75 L solution. What will be
the OH- concentration of the resulting solution if the Kb for the carbonate ion is 2.1 x 10-4?
9. When a student dissolves 7.50 g of ammonia in enough water to make 2.0 L solution, the OH concentration was found to be 1.9 x 10-3 mol/L. What is the Kb of the ammonia?
M/C and NR
1. The Kb for the conjugate base of hypochlorous acid is?
a) 2.5 x 10-7
b) 3.4 x 10-7
c) 6.8 x 10-8
d) 7.1 x 10-9
2. A 0.500 mol/L solution of hydrazine (N 2H4(aq) contains the following equilibrium concentrations:
[N2H4(aq)] = 0.498 mol/L
[OH-(aq)] = 2.14 x 10-3 mol/L
[N2H5+(aq)] = 2.14 x 10-3 mol/L
The Kb for hydrazine, in scientific notation, is a.bc x 10-d. The values of a, b, c, and d are, respectively,
_____ , _____ , _____, and _____ .
3. The Kb for NH3(aq) is?
a) -5.6 x 10-10
b) 1.0 x 10-14
c) 1.8 x 10-5
d) 1.8 x 109
4. If some NaOH(aq) was spilled, the spill could be neutralized by the addition of NaHSO4(aq). The net ionic
equation for this reaction is…
a) OH-(aq) + H3O+(aq) ⮀ 2 H2O(l)
b) OH-(aq) + HSO4-(aq) ⮀ H2O(l) + SO42-(aq)
c) NaOH(aq) + NaHSO4(aq) ⮀ H2O(l) + Na2SO4(aq)
d) 2 Na+(aq) + OH-(aq) + HSO4-(aq) ⮀ H2O(l) + 2 Na+(aq) + SO42-(aq)
5. The value for Kw…
a) is equal to the [H3O+(aq)] [OH-(aq)]
b) changes depending on the pH
c) show that adding OH-(aq) increases the [H3O+(aq)]
d) shows [OH-(aq)] can never be less than 1.00 x 10-14 mol/L
AB5 – Ka and Kb vs. pH and pOH
1. What is the difference between a strong acid and a concentrated acid? Is it possible to have a strong acid
and a weak acid with the same pH? Explain how this is possible.
2. A solution of hydrocyanic acid has a pH of 4.80. The concentration of the HCN (aq) solution is
a) 0.16 mol/L
b) 0.25 mol/L
c) 0.41 mol/L
d) 0.65 mol/L
3. Manufacturers add alum, Al 2(SO4)3(s), during the production of paper. The aluminium ion was hydrated and
the following equilibrium was established:
Al(H2O)63+(aq) + H2O(l) ⮀ Al(OH)(H2O)52+(aq) + H3O+(aq)
Ka = 1.4 x 10-5
If [Al(H2O)63+(aq)] = 0.150 mol/L, the pH of the system at equilibrium is __________ .
4. A 0.100 mol/L unknown acid solution is found to have a [H 3O+(aq)] equal to 0.0015 mol/L. The pH of this acid
solution is
a) 1.00
b) 2.82
c) 3.82
d) 13.00
5. A cleaning agent has a pH of 1, and a carbonated beverage has a pH of 5. The cleaning agent is more acidic
than the carbonated beverage by a factor of
a) 10 000
b) 1 000
c) 100
d) 10
6. Aqueous solutions of ammonium nitrate are acidic. A 0.20 mol/L solution of NH 4NO3(aq) would have a pH of
a) 0.70
b) 4.47
c) 4.98
d) 5.12
7. Rainwater is acidic because it contains dissolved atmospheric CO2(g) the occurs naturally. It may also contain
air pollutants, NOx(g), and SOx(g) from industrial sources. If each of the following components of acid rain is of
equal concentration, then which of them would have the lowest pH?
a) HNO3(aq)
b) HNO2(aq)
c) H2SO3(aq)
d) H2SO4(aq)
Use the following information to answer the next question.
Oxoacids of Chlorine
Acid
Ka
HClO4(aq)
very large
HClO3(aq)
5.1 x 102
HClO2(aq)
1.1 x 10-2
HClO(aq)
2.9 x 10-8
8. Acids are classified as either strong or weak. Of the acids listed above, only
a) HClO(aq) is a strong acid
b) HClO4(aq) is a strong acid
c) HClO4(aq) and HClO3(aq) are strong acids
d) HClO4(aq), HClO3(aq), HClO2(aq) are strong acids
9. Sodium azide, which is found in automobile airbags, reacts readily with acids to form the highly toxic and
explosive hydroazoic acid. HN3(aq). The Ka for hydroazoic acid is 1.9 x 10-5.
The pH of a 0.28 mol/l HN3(aq) solution is __________ .
M/C and NR
1. Given the following information
1
2
3
4
lime juice
salmon
apple cider
egg white
[OH-(aq)] = 7.7 x 10-13 mol/L
[H3O+(aq)] = 6.3 x 10-7 mol/L
[OH-(aq)] = 1.3 x 10-11 mol/L
[H3O+(aq)] = 3.0 x 10-8 mol/L
When these foods are listed from most acidic to least
acidic, the order is
____ ____ ____ ____ .
2. Household ammonia is a cleaning product in
which the concentration of ammonia is about 2
mol/L. The pOH of a 2 mol/L ammonia solution is
a) 2.2
b) 4.5
c) 9.5
d) 11.8
3. Which of the following is a correct statement
concerning an aqueous solution?
a) As [H 3O+(aq)] increases, [OH-(aq)] decreases.
b) As [H 3O+(aq)] increases, [OH-(aq)] increases.
c) As pH increases, [OH -(aq)] decreases.
d) As pH increases, [H 3O+(aq)] increases.
4. Given the net equation:
NH4+(aq) + H2O(l) ⮀ H3O+(aq) + NH3(aq)
In a system at equilibrium, the concentration of the
NH3(aq) is 0.35 mol/L and the concentration of the
NH4Cl(aq) is 0.25 mol/L. The pH of the NH4+(aq) /
NH3(aq) solution is __________ .
5. The pH of a 2.83 x 10-6 mol/L solution of
Ba(OH)2(aq) is __________ .
6. Household bleach contains sodium hypochlorite,
which is a weak base with a Kb of 3.4 x 10-7. The
ionization of sodium hypochlorite can be
represented by the following equilibrium equation
OCl-(aq) + H2O(l) ⮀ HOCl(aq) + OH-(aq)
The pOH of a 0.0125 mol/L solution of sodium
hypochlorite is
a) 1.90
b) 4.19
c) 8.37
d) 9.81
7. If the concentration of H3O+(aq) in a sulfuric acid
solution is 1.2 x 10-5 mol/L, then the pOH of this
solution is __________ .
Use this information for the next three
questions.
The Cancarb plant in Medicine Hat produces
carbon, C(s), from methane gas using thermal
decomposition at 1300°C. The reaction is
represented by the equation
CH4(g) ⮀ C(s) + 2 H2(g)
8. To cool the carbon in the production line, it is
sprayed with water. In this process, the water
becomes increasingly basic. The [OH-(aq)] of the
resulting solution is 3.2 x 10-4 mol/L. The pH of the
solution is
a) 0.50
b) 3.49
c) 10.51
d) 13.50
9. A solution prepared by mixing a sample of
carbon with NaCl(aq) has a pH of 9.93. The pOH of
this solution is __________ .
10. The purity of high-quality carbon can be
measured by soaking a sample in water and then
measuring its pH. “Ultrapure” grade has a pH of
6.00, and “Thermax” grade has a pH of 10.00. The
[OH-(aq)] of these two grades of high-quality carbon
are, respectively,
a) 1.0 x 10-6 mol/L and 1.0 x 10 -10 mol/L
b) 1.0 x 10-8 mol/L and 1.0 x 10 -4 mol/L
c) 4.0 mol/L and 8.0 mol/L
d) 8.0 mol/L and 4.0 mol/L
11. Morphine, (Mor(aq)), is a narcotic prescribed to
patients to diminish severe pain. Morphine can
react with water, as represented by the equilibrium
Mor(aq) + H2O(l) ⮀ HMor+(aq) + OH-(aq)
A 0.100 mol/L sample of Mor (aq) with a pH of 11.426
has an OH-(aq) concentration of
a) 3.75 x 10-12 mol/L
b) 1.94 x 10 -6 mol/L
-3
c) 2.67 x 10 mol/L
d) 1.00 x 10 -1 mol/L
0.10 mol/L solutions
1 NaNO2(aq)
3 HNO3(aq)
2 NaHCO3(aq)
4 Ba(OH)2(aq)
12. Given the following information
When the solutions above are ordered from most
basic to least basic, the order is
_____ _____ _____ _____ .
AB6: pH Curves and Indicators
1. In a chemical analysis of a nitric acid solution, 15.4 mL of a 0.10 mol/L potassium hydroxide solution was
added to a 10.0 mL sample. What is the concentration of the nitric acid solution?
2. Chemical analysis of a sulfurous acid sample was conducted in a lab. The titration was completed to the
end of the second quantitative reaction. The data obtained was as follows:
Titration of 10.0 mL of sulfurous acid with a 0.200 mol/L barium hydroxide solution
Trial
1
2
3
4
Final buret reading (mL)
14.2
28.0
42.4
56.3
Initial buret reading (mL)
0.300
14.2
28.0
42.4
What is the concentration of sulfurous acid?
3. 100.0 mL of a standard solution of sodium oxalate was prepared using 1.85 g of the dry solid. Using the
second endpoint, 10.0 mL samples were titrated with hydrochloric acid.
Titration of 10.0 mL samples of Na2OOCCOO(aq) with HCl(aq)
Trial
1
2
3
4
Final buret reading (mL)
16.1
31.5
46.9
16.9
Initial buret reading (mL)
0.3
16.1
31.5
What is the molar concentration of the hydrochloric acid solution?
4. Use the following graph to answer the set of questions below…
1.5
Titration Curve for the Titration of 37 mL of H 3PO4(aq) with 0.10 mol/L NaOH(aq)
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Does the burette contain the acid or the base?
The initial [H3O+(aq)].
The number of quantitative reactions.
The equivalence point pH for each quantitative reaction.
The equivalence point volume for each quantitative reaction.
Choose and appropriate indicator for each endpoint.
Which indicator would you use for this titration? Explain why.
Write a double replacement rxn for the region before point I and for the region between point I and point II.
Write a Bronsted-Lowry rxn for the region before point I and for the region between point I and point II.
Determine the concentration of the acid in this titration.
MC/NR
Titration of an unidentified base
1. Which indicators can be used to
accurately estimate the first and second
equivalence points?
a) orange IV
c) methyl orange
b) thymol blue
d) phenolphthalein
Indicator
Color of Solution
orange IV
yellow
methyl red
orange
phenol red
yellow
phenolphthalein
colorless
4. In which 0.10 mol/L solution would
bromothymol blue turn green?
a) NaOH(aq)
b) K2CO3(aq)
c) NaCl(aq)
d) HOOCCOOH(aq)
5. Given the following information:
a) thymolphthalein; methyl orange
b) thymolphthalein; thymol blue
c) alizarine yellow; thymol blue
d) all of the above
An acidic solution was titrated with NaOH(aq)
and the points were plotted below.
The pH of the unidentified solution is
approximately
a) 3.0
b) 5.2
c) 6.2
d) 8.0
6. The sketch that indicates the change that
occurs when 1.0 mol/L HNO 3(aq) is added to
20 mL of 1.0 mol/L NH 3(aq) is
2. The best choice of indicator for this
titration is
a) orange IV
b) indigo carmine
c) phenolphthalein
d) chlorophenol red
3. Given the following information:
Indicator
Color of Solution
orange IV
yellow
thymol blue
yellow
methyl orange
red
phenolphthalein
pink
For which indicator is the colour correct in
0.10 mol/L HCl (aq) solution?
7. The water in a swimming pool was tested
to determine its pH. Phenolphthalein was
colorless in a sample of the water and
bromothymol blue was blue.
The approximate pH of the swimming pool
water was
a) 6.3
b) 7.0
c) 8.0
d) 12.0
8.
Δ H°f
(kJ/mol
Ka
)
HF
-83
-271.1
6.3 x 10-4
HCl
-114
-92.3
1.3 x 106
HI
-87
+26.5
3.2 x 109
HBr
-51
-36.4
1.0 x 109
10. The halide acid that would generate the
data on the above graph is
Hydroge
n Halide
Melting
Point (°C)
a) HF(aq)
c) HI(aq)
b) HCl(aq)
d) HBr(aq)
11. The indicator that would best signal the
endpoint of this titration is
The above graph represents the titration of
a) hydrochloric acid with ammonia
d) acetic acid with sodium hydroxide
c) sodium hydroxide with hydrochloric acid
b) potassium hydroxide with oxalic acid
Use the following information to answer
the next three questions.
Given the following information:
9. The hydrogen halides, ordered from the
strongest acid to weakest acid, are
a) HI, HBr, HCl, HF
b) HBr, HI, HCl, HF
c) HBr, HCl, HI, HF
d) HF, HI, HCl, HBr
a) methyl orange
c) indigo carmine
b) phenolphthalein
d) bromothymol blue
12. A solution was tested and found to have
a pOH of 10.2. This solution would most
likely?
a) be a proton acceptor
b) react violently with zinc
c) cause phenolphthalein to be pink
d) cause bromocresol green to be blue
Use the following information to answer
the next question.
A sample of rainwater is poured into five test
tubes. A different indicator is added to each
test tube. Four of the observations are
recorded in the table below.
Indicator
Colour of
Sample
phenol red
yellow
bromocresol green
blue
phenolphthalein
colourless
bromothymol blue
?
13. The pH of the rainwater is ___i___and
the predicted colour of the sample containing
bromothymol blue is ___ii___.
Row
i
ii
a)
6.0
blue
b)
7.6
blue
c)
6.0
yellow
d)
7.6
yellow
14. According to the acid-base indicator
table, what is the color of each of the
following solutions of given pH?
a) phenolphthalein in solution with pH = 11.7
b) bromothymol blue in solution with pH = 2.8
c) litmus in solution with pH = 8.2
d) methyl orange in solution with pH = 3.9
AB7: pH Buffer Solutions
1. One important buffer that exists in blood is the
H2PO4-(aq) / HPO42-(aq) system. The net ionic
equation that represents the reaction of
HCl(aq) , with this buffer is
+
(aq)
24 (aq)
4 (aq)
4 (aq)
24 (aq)
a) H3O
+ HPO
b) HCl(aq) + H2PO
c) H3O+(aq) + H2PO
d) HCl(aq) + HPO
4 (aq)
⮀ H2PO
+ H2O(l)
⮀ H3PO4(aq) + Cl-(aq)
⮀ H3PO4(aq) + H2O(l)
⮀ H2PO4-(aq) + Cl-(aq)
5. In this reaction, the substances that act as
Bronsted-Lowry acids are
a) OCl-(aq) and H2O(l)
c) OCl-(aq) and OH-(aq)
b) OCl-(aq) and HOCl(aq)
d) H2O(l) and HOCl(aq)
6. The two species in equimolar amounts that
could act as a buffer in this bleach system are
2.
a) OCl-(aq) and HOCl(aq)
c) OCl-(aq) and H2O(l)
b) HOCl(aq) and OH-(aq)
d) H2O(l) and OH-(aq)
7. In this bleach solution, the acid base indicator
a) phenolphthalein would be colorless
b) alizarin yellow R would be orange
c) indigo carmine would be green
d) methyl orange would be red
If the titration is stopped at X, the solution is
resistant to a change in pH if a strong base or a
strong acid is added to it. This is due to the fact
that, at X, the solution contains large amounts of
8. A student titrated an unknown sample of an
aqueous acid with aqueous sodium hydroxide. The
student graphed the data as shown in the diagram
below.
a) H2O(l) and OH-(aq)
b) CH3COO-(aq) and H3O+(aq)
c) CH3COOH(aq) and OH-(aq)
d) CH3COOH(aq) and CH3COO-(aq)
3. An important buffer in blood is the H 2CO3(aq) /
HCO3-(aq) system. The equilibrium for this buffer is
H2CO3(aq) + H2O(l) ⮀ H3O+(aq) + HCO3-(aq)
A sample of this buffer at equilibrium contains 1.1 x
10-4 mol/L of HCO 3-(aq) and 1.2 x 10-5 mol/L
H2CO3(aq). The pH of the sample is __________ .
Use the following information to answer the next
four questions.
Prairie Chem Inc. in Edmonton is a bulk
manufacturer of concentrated bleach (NaOCl(aq)).
The bleach reacts with water to form a solution with
a pH of 10.87.
OCl-(aq) H2O(l) ⮀ HOCl(aq) + OH-(aq)
4. The substance in the equation above that may
act as an amphiprotic species is
a) OCl-(aq)
b) H2O(l)
c) HOCl(aq)
d) OH-(aq)
The graph of the student’s titration data shows
the titration of a ___i___ acid with a strong
base, and on the graph, buffering occurs at
___ii___ .
Row
a)
b)
c)
d)
i
strong
strong
weak
weak
ii
region II only
regions II and IV
region II only
region II and IV