Approximately .
Explanation:
The in this question refers the dissociation equilibrium of as an acid:
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However, the question also states that the solution here has a of , which means that this solution is basic. In basic solutions at , the concentration of ions is considerably small (typically less than .) Therefore, it is likely not very appropriate to use an equilibrium involving the concentration of ions.
Here's the workaround: note that is the conjugate base of the weak acid . Therefore, when dissociates in water as a base, its would be equal to . ( is the self-ionization constant of water. at .)
In other words,
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And that value corresponds to the equilibrium:
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The value of has already been found.
The concentration of this solution can be found from its value:
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To determine the concentration of , consider the following table:
Before hydrolysis, the concentration of both and are approximately zero. Refer to the chemical equation. The coefficient of and are the same. As a result, this equilibrium will produce and at the exact same rate. Therefore, at equilibrium, .
Calculate the equilibrium concentration of from :
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