Concept explainers
A buffer is prepared using the butyric acid/butyrate
(a) What is the pH of this buffer?
(b) Enough strong base is added to convert 15% of butyric acid to the butyrate ion. What is the pH of the resulting solution?
(c) Strong acid is added to the buffer to increase its pH. What must the acid/base ratio be so that the pH increases by exactly one unit (e.g., from 2 to 3) from the answer in (a)?
(a)
Interpretation:
The butyric acid and butyrate base is used to prepare the buffer solution. The ratio butyric acid and butyrate base is
Concept introduction:
The buffer solution is formed by the mixture of acid and the conjugate base. It is an aqueous solution which maintains the pH of the solution constant for many chemical applications.
The formula of the pH is −
Answer to Problem 34QAP
The pH value of this buffer solution is 4.47.
Explanation of Solution
The chemical equation for the buffer solution can be represented as-
The equilibrium constant of acid for the above equation can be written as-
Or, it can be represented as follows:
Given that-
Ka = 1.54×10-5 for
Put the above values in equation (1),
The pH value of the solution-
The pH value of solution = 4.47
(b)
Interpretation:
The butyric acid is converted to butyrate ion by adding 15% of the strong base. The pH value of this solution is to be determined.
Concept introduction:
The buffer solution is formed by the mixture of acid and the conjugate base. It is an aqueous solution which maintains the pH of the solution constant for many chemical applications.
The formula of the pH is −
Answer to Problem 34QAP
The pH value of this solution is 4.66 when the butyric acid is converted to butyrate ion by adding 15% of the strong base.
Explanation of Solution
The calculated value-
Therefore,
Given that −
Or,
The butyric acid is converted to butyrate ion by adding 15% of the strong base.
Given −
Therefore,
The value of
Given that-
Ka = 1.54×10-5 for
Put the above values in equation (1),
The pH value of the solution-
The pH value of solution = 4.66
(c)
Interpretation:
The pH value of the buffer solution is increased by adding strong acid to this solution. In this case, the ratio of
Concept introduction:
The buffer solution is formed by the mixture of acid and the conjugate base. It is an aqueous solution which maintains the pH of the solution constant for many chemical applications.
The formula of the pH is −
Answer to Problem 34QAP
The ratio of
Explanation of Solution
The chemical equation for the buffer solution can be represented as-
The equilibrium constant of acid for the above equation can be written as-
Or, it can be represented as-
Given that-
Ka = 1.54×10-5 for
Given that pH value is increased by one unit. Initial pH value is 4.47.
The pH value is 5.47. Then the concentration of H+ -
Then the ratio is calculated by using equation (1)-
Given −
Ka = 1.54×10-5
Put the values in equation (3)
Or,
Then, the ratio
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