Acids and Bases Jeopardy
Acid
Calculations
Base
Calculations
Concentration of
species
Titration Curves
Pot Luck
100
100
100
100
100
200
200
200
200
200
300
300
300
300
300
400
400
400
400
400
500
500
500
500
500
Final Jeopardy
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©Norman Herr, 2003
Acid Calculations-100
• QUESTION: Calculate the pH of a solution
containing 0.134 molL-1 hydronium ions
• ANSWER: 0.873
Answer
Question
Acid Calculations-200
• QUESTION: Calculate the pH of 1.35 x
10-9 molL-1 HCl
• ANSWER: 6.99
Answer
Question
Acid Calculations-300
• QUESTION: Calculate the pH of 3.0 x
10-4 molL-1 H2SO4
• ANSWER: 3.22
Answer
Question
Acid Calculations-400
• QUESTION: Calculate the pH of an acid
with a hydroxide ion concentration of
1.38 x 10-10 molL-1
• ANSWER: 4.14
Answer
Question
Acid Calculations-500
• QUESTION: Calculate the pH of 0.0243
moL-1 ethanoic acid, given Ka = 1.74 x 10-5
• ANSWER: 3.19
Answer
Question
Base Calculations-100
• QUESTION: Calcuate the pH of 0.1
molL-1 hydroxide ions
• ANSWER: 13
Answer
Question
Base Calculations-200
• QUESTION: Calculate the pH of 0.153
molL-1 KOH
• ANSWER: 13.2
Answer
Question
Base calculations-300
• QUESTION: Calculate the hydroxide ion
concentration of a 3.02 x 10-4 molL-1 HCl
solution
• ANSWER: 3.31 x 10-11 molL-1
Answer
Question
Base Calculations-400
• QUESTION: If the pH is 8.65, what is the
concentration of hydronium ions?
• ANSWER: 4.47 x 10-6 molL-1
Answer
Question
Base calculations-500
• QUESTION: Calculate the pH of a 0.107
molL-1 solution of NH3, given the pKa of
the ammonium ion is 9.75
• ANSWER: 11.4
Answer
Question
Concentration of species-100
• QUESTION: From highest to lowest
concentration, what are the species
present in a 1 molL-1 solution of H2SO4?
• ANSWER: H2O>>H3O+>SO42->OH-
Answer
Question
Concentration of species-200
• QUESTION: From highest to lowest
concentration, what are the species
present in a 1 molL-1 solution of
CH3COOH?
• ANSWER: H2O>> CH3COOH>H3O+
=CH3COO->OH-
Answer
Question
Concentration of species-300
• QUESTION: From highest to lowest
concentration, what are the species
present in a 1 molL-1 solution of NH3?
• ANSWER: H2O >> NH3 > OH- = NH4+ >
H 3O +
Answer
Question
Concentration of species-400
• QUESTION: From highest to lowest
concentration, what are the species
present in a 1 molL-1 solution of
NH4NO3?
• ANSWER: H2O >> NO3- = NH4+ >H3O+ =
NH3 > OH-
Answer
Question
Concentration of species-500
• QUESTION: From highest to lowest
concentration, what are the species
present in a 1 molL-1 solution of
HCOONa?
• ANSWER: H2O >> HCOO- = Na+ > OH= HCOOH > H3O+
Answer
Question
Titration curves-100
• QUESTION: The concentration of HPab (a weak acid)
solution was determined by titration. A 20.0 mL sample of the
HPab solution required 12.0 mL of 0.0500 mol L–1 NaOH to reach
the equivalence point. The equation for the reaction occurring is
HPab + NaOH → NaPab + H2O
Calculate the concentration of the HPab solution.
• ANSWER: 0.03 molL-1
Answer
Question
Titration curves-200
• QUESTION: Explain why the pH at the equivalence point for
this titration is less than 7. (Include an equation to support your answer.)
• ANSWER:
Titration is weak base
strong acid. At equivalence
point there is the conjugate
acid of the weak base
which means pH<7
NH3 +HCl→ NH4+ + Cl-
Answer
Question
Titration curves-300
• QUESTION: What is the Ka for the acid
shown?
• ANSWER:
1.78 x 10-10
Answer
Question
Titration curves-400
• QUESTION: 20.0 mL of the weak acid HPab (0.03
molL-1) is titrated against 0.05 molL-1 NaOH. The Ka
of (Pab-) is 1.2 x 10-5. Its initial pH is 3.22. Using the
information above, sketch a curve showing the change
in pH against the volume of sodium hydroxide added to
the solution in the flask.
• ANSWER: Curve has: pH 3.22 at 0mL,
4.92 at 6 mL, and end point pH 8-10 at
12 mL, correct shape
Answer
Question
Titration curves-500
• QUESTION: A titration is carried out –
40.0 mL of 0.0500 mol L–1 NaOH solution
is titrated against 0.200 mol L–1
CH3COOH solution. Calculate the pH
after 5 mL CH3COOH added.
• ANSWER: 12.3
Answer
Question
Pot luck-100
• QUESTION: The titration
curve is for ethanoic acid + NaOH.
What is the Ka for ethanoic acid?
Show working
• ANSWER:
pH = pKA at ½ moles
base added. So pKa = 5.
Ka =
10-5 =
1x
10-5
Answer
14
13
12
11
pH 10
9
8
7
6
5
4
3 A
2
1
0
2
Question
D

C
B

4
6
8 10 12 14 16 18 20
Volume of NaOH (mL)
Pot luck-200
• QUESTION: The titration
curve is for ethanoic acid + NaOH.
List the species present in
decreasing concentration at point B
• ANSWER:
H2O>>CH3COOH
= CH3COO-=Na+>OH-
Answer
14
13
12
11
pH 10
9
8
7
6
5
4
3 A
2
1
0
2
Question
D

C
B

4
6
8 10 12 14 16 18 20
Volume of NaOH (mL)
Pot luck-300
• QUESTION:
Indicator
pKa
Thymol blue
1.7
Chlorophenol red 6.1
Cresol red
8.3
Choose the best indicator for
the titration. Give a reason.
• ANSWER:
Cresol red – its pKa means it
would change colour in the range
of the equivalence pint of the titration
Answer
14
13
12
11
pH 10
9
8
7
6
5
4
3 A
2
1
0
2
Question
D

C
B

4
6
8 10 12 14 16 18 20
Volume of NaOH (mL)
Pot luck-400
• QUESTION:
Discuss how a buffer solution of pH = 3.3 could be prepared from
solutions of 0.01 mol L–1 HNO2 and 0.01 mol L–1 KOH. Include
relevant equations in your answer. pKa (HNO2) = 3.3
• ANSWER:
Mix 10 mL of HNO2 with 5 mL of KOH.(or equivalent)
HNO2 + OH–  NO2– + H2O
At half neutralisation conc. HNO2 = conc. NO2- and
therefore
Ka = H3O+
pKa = pH
Answer
Question
Pot luck-500
• QUESTION:
An acid base indicator has the formula HIn. It is yellow in the presence of any acid
solution and blue in the presence of any base solution. pKa for HIn is 7.0. Using
chemical equations explain how such an indicator works. Explain under what
conditions and pH the indicator is green.
• ANSWER:
The indicator HIn is a weak acid and reacts with water as shown in the
equation.
HIn(aq) + H2O(aq) → In-(aq) + H3O+(aq)
The HIn form of the indicator is yellow and the In- form is blue. If acid, i.e.
hydronium ions are added to the indicator solution, the position of
equilibrium is shifted to the left hand side, forming more HIn and
therefore giving an yellow colour. If base is added to the indicaor solution,
the hydronium ions will react with it, shifting the equilibrium position to
the right, forming more In-, and therefore giving a blue colour. At apH of
7 the concentration of the HIn and the In- will be equal and the colour of
the solution will be a mixture of blue and yellow, i.e. green.
Answer
Question
FINAL JEOPARDY
• ANSWER:
• QUESTION:
Answer
Question