Concept explainers
(a)
Interpretation: The pH of the solution before addition of KOH needs to be determined.
Concept Introduction: The acid dissociation reaction of
The acid dissociation constant for the above three reactions will be
(a)
Explanation of Solution
Before KOH is added, the pH of the solution depends on concentration of acid.
The first dissociation of
The given concentration of
The first acid dissociation constant can be represented as follows:
Or,
On solving,
This is the concentration of hydrogen ion in the solution. Thus, pH can be calculated as follows:
(b)
Interpretation: The pH of the solution after addition of 10 mL of 0.1 M KOH needs to be determined.
Concept Introduction: The acid dissociation reaction of
The acid dissociation constant for the above three reactions will be
(b)
Explanation of Solution
The number of moles of
Now, hydroxide ion will react with
Thus,
Thus, the amount of
The total volume will be 110 mL thus, concentration can be calculated as follows:
The ICE table can be prepared as follows:
The equilibrium expression can be represented as follows:
Or,
On solving,
The pH of the solution will be:
(c)
Interpretation: The pH of the solution after addition of 25 mL of 0.1 M KOH needs to be determined.
Concept Introduction: The acid dissociation reaction of
The acid dissociation constant for the above three reactions will be
(c)
Explanation of Solution
The molar amount of hydroxide ion initially present can be calculated as follows:
The reaction of hydroxide ion and H3X to produce
Thus, the amount of H3X left can be calculated as follows:
The concentration of H3X is equal to concentration of
(d)
Interpretation: The pH of the solution after addition of 50 mL of 0.1 M KOH needs to be determined.
Concept Introduction: The acid dissociation reaction of
The acid dissociation constant for the above three reactions will be
(d)
Explanation of Solution
The number of moles of hydroxide ion can be calculated as follows:
The hydrogen ion reacts with H3X and the amount is equal to that of hydroxide ion.
The remaining amount of H3X will be:
Now, all the acid exists as
The pH can be calculated as follows:
(e)
Interpretation: The pH of the solution after addition of 60 mL of 0.1 M KOH needs to be determined.
Concept Introduction: The acid dissociation reaction of
The acid dissociation constant for the above three reactions will be
(e)
Explanation of Solution
The number of moles of hydroxide ion can be calculated as follows:
Initially 5 mmol of hydroxide ion react with H3X and the remaining will react to with
The amount of
The molarity can be calculated as follows:
Also, the molarity of
The ICE table can be prepared as follows:
The expression for
The
This is the concentration of hydrogen ion.
The pH value can be calculated as follows:
(f)
Interpretation: The pH of the solution after addition of 75 mL of 0.1 M KOH needs to be determined.
Concept Introduction: The acid dissociation reaction of
The acid dissociation constant for the above three reactions will be
(f)
Explanation of Solution
The number of moles of hydroxide ion can be calculated as follows:
Initially 5 mmol of hydroxide ion react with H3X and the remaining will react to with
Thus, the amount of
Here, the concentration of
Thus, pH value can be calculated as follows:
(g)
Interpretation: The pH of the solution after addition of 100 mL of 0.1 M KOH needs to be determined.
Concept Introduction: The acid dissociation reaction of
The acid dissociation constant for the above three reactions will be
(g)
Explanation of Solution
The initial number of moles of hydroxide ion can be calculated as follows:
Initially 5 mmol of hydroxide ion react with H3X and the remaining will react to with
The amount of
Now, only
The pH can be calculated as follows:
Putting the values,
(h)
Interpretation: The pH of the solution after addition of 125 mL of 0.1 M KOH needs to be determined.
Concept Introduction: The acid dissociation reaction of
The acid dissociation constant for the above three reactions will be
(h)
Explanation of Solution
The initial number of moles of hydroxide ion can be calculated as follows:
Initially 5 mmol of hydroxide ion react with H3X and the remaining will react to with
The remaining hydroxide ion will react to form
The amount of
The molarity can be calculated as follows:
Similarly, for
This is third equivalence point and the ICE table can be represented as follows:
The base dissociation constant can be represented as follows:
The equation will be:
On solving, the value of x will be:
This is concentration of hydroxide ion, the pH value can be calculated as follows:
Putting the values,
(i)
Interpretation: The pH of the solution after addition of 150 mL of 0.1 M KOH needs to be determined.
Concept Introduction: The acid dissociation reaction of
The acid dissociation constant for the above three reactions will be
(i)
Explanation of Solution
The hydrogen ion concentration in the beginning can be calculated as follows:
Initially 5 mmol of hydroxide ion react with H3X and the remaining will react with
The remaining hydroxide ion will react to form
The amount of
The molarity for
The ICE tale will be:
The base dissociation constant can be represented as follows:
The equation will be:
On solving, the value of x will be:
This is concentration of hydroxide ion, the pH value can be calculated as follows:
Putting the values,
(j)
Interpretation: The pH of the solution after addition of 200 mL of 0.1 M KOH needs to be determined.
Concept Introduction: The acid dissociation reaction of
The acid dissociation constant for the above three reactions will be
(j)
Explanation of Solution
The hydrogen ion concentration in the beginning can be calculated as follows:
Now, to convert
The remaining number of moles of hydroxide ion will be 5 mmol.
The molarity of
The reaction of hydroxide ion with
The base dissociation constant can be represented as follows:
The equation will be:
On solving, the value of x will be:
The hydroxide ion concentration will be:
This is concentration of hydroxide ion, the pH value can be calculated as follows:
Putting the values,
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Chapter 8 Solutions
Chemical Principles
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