How many moles of HCOONa must be added to 1L of 0.1 M HCOOH to prepare a buffer solution with a pH of 3.4(given: Ka for HCOOH = 2*10^-4)

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Nakul01 · Answer 1 · 2020-01-04T22:22:33+0000

pH of buffer solutions is calculated using handerson equation:

Here, the acid is formic acid that is HCOOH and its conjugate base is HCOO^- which is given as the salt, HCOONa.

Moles of acid could be calculated from its given molarity and volume as:

The pH is given as 3.4. Pka for formic acid could be found in the data table which is 3.75.

Let's plug in the values in the equation and solve for the moles of sodium formate.

So, 0.045 moles of HCOONa are required.