Question #ce2a2

1 Answer
Apr 28, 2017

To understand why this is, we'll need to take a look at how a buffer works.


A buffer, by definition, is a solution containing a weak acid, and it's conjugate base (usually added through the form of a salt). This can also be made by a weak base and it's conjugate acid.

The main selling point of a buffer is that it minimizes pH changes within a certain range. How? Consider the balanced chemical equation for the acid-dissociation reaction for HCN:

#HCN_((aq)) + H_2O_((l)) rightleftharpoons CN_((aq))^(-) + H_3O_((aq))^+#

The idea is that you have significant concentrations of both your weak acid (#HCN#) and conjugate base (#CN^-#).

Now, if you add some strong acid (ex. #HCl#) to this buffer solution, it will react with your weak base, and produce conjugate base and water (the reverse of the above reaction). Hence, you will not see a drastic change in pH. Same is true if you add a conjugate base -- it will react with the conjugate acid to produce conjugate base and water.

That, on an intuitive level, is how a buffer works. Your buffer satisfies those conditions, as you have concentrations of both a weak acid and conjugate base.

If you'd like some additional information on buffers, check out this video .

How do you determine in what pH range a buffer works? Learn about that here .

Hope that helps :)