Calculate Ka value for 3 different points in HCOOH titration. Here are my data:

Question

Calculate Ka value for 3 different points in HCOOH titration. Here are my data: 0% to equivalence point- PH=2.00 50% to EP- PH=3.98 75% to EP- PH= 24.23 Concentration of HCOOH solution from the stock bottle is 0.5M. The reaction equation is HCOOH+ H2O-> HCOO- +H3O+ How to do three calculations to get Ka value for 3 different points above? Calculate Ka value for 3 different points in HCOOH titration. Here are my data: 0% to equivalence point- PH=2.00 50% to EP- PH=3.98 75% to EP- PH= 24.23 Concentration of HCOOH solution from the stock bottle is 0.5M. The reaction equation is HCOOH+ H2O-> HCOO- +H3O+ How to do three calculations to get Ka value for 3 different points above? How to do three calculations to get Ka value for 3 different points above?

Explanation / Answer

You have been provided with the value of PH at half equivalence point, for titration of a weak acid the PH at the half equivalence point is equal to the PKa

so PKa = PH (half equivalence point) = 3.98 according to the statement

PKa = - log Ka

Ka = 10-ka = 10-3.98 = 0.00010471 or 1.04 x 10-4

The Ka means acidity constant, it is a specific value for a weak acid, this value will not change along the titration the only thing that changes is the PH.

Note = from internet i get a value of pka for formic acid = 3.75, the value you have provided is very close to the theoretical value

*please rate the answer if you like it =)

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