Concept explainers
Barbituric acid, HC4H3N2O3, is used to prepare barbiturates, a class of drugs used as sedatives. Its Ka is
(a) 0.344 mol
(b) 28.9 g
(a)
Interpretation:
The concentration of hydrogen ion in the given solution should be calculated.
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,
Answer to Problem 51QAP
Explanation of Solution
The acid dissociation constant of barbituric acid is
The molarity of
Putting the values,
Thus, the concentration of
The concentration all the species can be calculated using the ICE table as follows:
The expression for
Putting the values,
On rearranging,
Or,
Comparing this with the general quadratic equation as follows:
Solving the quadratic equation,
Putting the values,
Since, the value of x cannot be negative thus, the value of x will be
From the ICE table, it is equal to the concentration of hydrogen ion thus,
Therefore, the concentration of hydrogen ion is
(b)
Interpretation:
The concentration of hydrogen ion in the given solution should be calculated.
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,
Answer to Problem 51QAP
Explanation of Solution
The mass of barbituric acid is given as 28.9 g. The molecular formula of the barbituric acid is
Now, from mass and molar mass of the
Now, the molarity of
Putting the values,
Thus, the concentration of
The concentration all the species can be calculated using the ICE table as follows:
The expression for
Putting the values,
On rearranging,
Or,
Comparing this with the general quadratic equation as follows:
Solving the quadratic equation,
Putting the values,
Since, the value of x cannot be negative thus, the value of x will be
From the ICE table, it is equal to the concentration of hydrogen ion thus,
Therefore, the concentration of hydrogen ion is
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Chapter 13 Solutions
Chemistry: Principles and Reactions
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