Concept explainers
Phthalic acid H2C8H4O4, is a diprotic acid. It is used to make phenolphthalein indicator.
Interpretation:
The pH of solution, the concentration of
Concept introduction:
The dissociation reaction of a weak acid is represented as follows:
The expression for the acid dissociation constant will be as follows:
Here,
The pH of the solution is calculated as follows:
Here,
Answer to Problem 61QAP
The pH of solution is 1.23, the concentration of
Explanation of Solution
The molecular formula of phthalic acid is
The molarity of solution is 2.9 M.
The concentration of each species can be calculated using the ICE table as follows:
Now, the second ionization reaction is represented as follows:
According to above two ICE tables, the equilibrium concentration of
The expression for dissociation constant is as follows:
Putting the values,
Similarly, the expression for the second ionization constant is as follows:
Putting the values,
Since, the second dissociation constant is very low thus; the value of y can be neglected from the denominator in the equation (2)
Thus, the value of y is
From the ICE table, it is concentration of
Now, in the equation (1),
Calculate the ratio of acid dissociation constant and concentration of acid; if it is less than 0.05 then the value of x from the denominator can be neglected.
The calculated value is less than 0.05 thus,
Or,
Putting the value of y in the above equation,
Or,
Thus, the concentration of
Putting the values,
The concentration of
Putting the values,
The pH of the solution can be calculated as follows:
Putting the values,
Therefore, the pH of solution is 1.23, the concentration of
Therefore, the pH of solution is 1.23, the concentration of
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Chapter 13 Solutions
Chemistry: Principles and Reactions
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