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General Chemistry

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Acid-base Equilibrium

Question
10 out of 10
 

Strong acids and bases ionize completely in aqueous solutions. Weak acids and bases ionize only partially in aqueous solutions. An acid-base reaction is shown below. A titration was done by adding a base to a known concentration and fixed volume of an acid. The reaction follows:

The dissociation of a weak acid can be represented as:

Chemists often use Henderson-Hasselbach equation to calculate the pH of solutions containing a weak acid of known pKa, provided that the other concentrations are known. Henderson-Hasselbach equation is:

This equation is also used to calculate the buffering capability of solutions. It is roughly estimated that a given buffer is most likely to be effective at pH levels between (pKa + 1) and (pKa – 1).


The pH at which the base and the acid concentrations equal in a buffer system is called the:

A Equivalence point
B pKa
C Neutralization point
D Non-buffering zone
Ans. B This is actually one way of defining pKa value. At the pKa value, the acid-base ratio is 1. So the best answer is Choice B. In addition, it is near the pKa value that the solution will have its best buffering capacity. So Choice D wrong.

Acid-base Equilibrium Flashcard List

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