You are asked to prepare a ph = 4.00 buffer starting from 1.50 l of 0.0200 m solution of benzoic acid (c6h5cooh and some added s

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You are asked to prepare a ph = 4.00 buffer starting from 1.50 l of 0.0200 m solution of benzoic acid (c6h5cooh and some added s

odium benzoate salt (c6h5coona. a find the ph of the benzoic acid solution before adding the salt. b use the henderson-hasselbalck equation to derive how many moles of the salt you should add. c how many grams of the salt should you add?

Chemistry

1 answer:

sveta [45] · Answer 1 · 2022-05-14T09:00:47+03:00

The <span>henderson-hasselbalck equation is this
pH = pK + log [salt]/[acid]

We are given with
pH = 4.00
</span><span>1.50 l of 0.0200 m solution of benzoic acid

The pK for benzoic acid is
4.20

Solving for the moles of salt,
4 = 4.2 + log 1.5(0.02)/n
n = 71.62 moles
The mass is
m = 71.62 (249.2)
m = 17800 grams</span>