Question #9732f

1 Answer
May 20, 2017

Answer:

You can't do it.

Explanation:

To make a buffer with pH = 9, you need an acid with #"p"K_text(a) = 9 ± 1#.

Citric acid is a tribasic acid with the formula #"C"_6"H"_8"O"_7# or #"H"_3"C"_6"H"_5"O"_7#.

The weakest form of the acid, #"HC"_6"H"_5"O"_7^"2-"# has a #"p"K_text(a)# of only 6.40.

Thus, you can't use it to make a buffer with pH = 9.

However, it would be great for making a buffer with pH = 7.