Did I Prepare My Phosphate Buffer Solution Correctly?

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The discussion centers on the preparation of a 0.1M phosphate buffer solution at pH 7.0 using the Henderson-Hasselbalch equation. The user calculated 0.062 moles of H2PO4- and 0.038 moles of HPO42- but questioned their accuracy. Clarification was sought regarding the pKa used and the identification of the salt and acid species. After confirming the correct species and calculations, the user concluded that their preparation was indeed correct. The thread emphasizes the importance of proper species identification and pKa selection in buffer preparation.
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Hi everybody!
I want to prepare 1000 ml of 0.1M phosphate buffer solution, pH = 7.0. I used Henderson Hasselbach's equation: pH = pka + log [salt]/[acid]. I obtained 0.062 moles of H2PO4- and 0.038 moles of HPO42-. Where I am wrong? Thanks a lot!
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Show your work. Which pKa did you use? What species did you use for [salt] and [acid]?
 
Thanks for replying!

I used (H2PO4)- ↔H+ + (HPO4)2-
Ka for this equation is 6.2*10-8, deci pKa = 7.21.
Salt = (HPO4)2-
Acid = (H2PO4)-
 
I get the same...
 
So, I did it right! Thanks!
 

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