Concept explainers
Calculate the
Interpretation:
The
of the buffer solution
and
in the solution are to be calculated.
Concept introduction:
Acid–base titration is a technique to analyse the unknown concentration of the acid or base through a known concentration of the acid and base.
The buffers are those solutions that resist a change in pH on the addition or dilution of a small amount of an acid or alkali, and they consist of a mixture of the weak acid with its salt of the strong base or the weak base with its salt of the strong acid.
Answer to Problem 16QP
Solution:
a)
The
of the buffer solution is
after the addition of
of the buffer solution is increased from
b)
The
of the buffer solution is
after the addition of
of the buffer solution is decreased from
Explanation of Solution
Given information: The concentration of acetic acid and sodium acetate is
each.
The volume of the buffer solution is
a)
NaOH
As it is a buffer solution, it is a mixture of weak base with its conjugate acid.
The
value of
The pH of the buffer solution is given by the expression as follows:
Here,
is the concentration of acetic acid and
Substitute the values of the concentrations of acetic acid and acetate ion and the dissociation constant of acetic acid in the above expression,
Hence,
of the buffer solution is
in the buffer solution.
is a strong base. It completely dissociates into its ions in the aqueous solution.
The equation for the dissociation of
The Initial Change Equilibrium table for dissociation of
The Initial Change Equilibrium table for neutralization reaction of
is as follows:
Consider
to be a degree of dissociation.
The Initial Change Equilibrium table for ionisation of
is as follows:
The equilibrium expression for a reaction is represented below.
Here,
is the concentration of acetic acid,
Substitute the value of
Solve further,
The value
The concentration of
The value of
in the solution is calculated by the expression as follows:
Substitute the value of
Therefore,
of the buffer solution is
of the buffer solution is increased from
b)
in the buffer solution.
The equation for the dissociation of
The Initial Change Equilibrium table for dissociation of
is as follows:
The Initial Change Equilibrium table for neutralization reaction of
with
is as follows:
Consider
to be a degree of dissociation.
The Initial Change Equilibrium table for ionisation of
is as follows:
The equilibrium expression for a reaction is represented by the expression as follows:
Here,
is the concentration of acetic acid,
is the concentration of hydronium ion, and
Substitute the values of
in the above expression,
The value
is very small as compared to
The concentration of
The value of
in the solution is calculated by using expression as follows:
Substitute the value of
Therefore,
of the buffer solution is
of the buffer solution is decreased from
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Chapter 17 Solutions
Package: Loose Leaf Chemistry with Connect 2-year Access Card
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