• Support PF! Buy your school textbooks, materials and every day products Here!

Phosphate buffer

  • Thread starter brendw2005
  • Start date
  • #1
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!
B
 

Answers and Replies

  • #2
chemisttree
Science Advisor
Homework Helper
Gold Member
3,293
300
Show your work. Which pKa did you use? What species did you use for [salt] and [acid]?
 
  • #3
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)-
 
  • #4
chemisttree
Science Advisor
Homework Helper
Gold Member
3,293
300
I get the same...
 
  • #5
So, I did it right! Thanks!
 

Related Threads on Phosphate buffer

  • Last Post
Replies
5
Views
69K
  • Last Post
Replies
2
Views
7K
  • Last Post
Replies
6
Views
2K
Replies
2
Views
14K
Replies
6
Views
4K
  • Last Post
Replies
4
Views
6K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
4
Views
4K
Replies
2
Views
9K
  • Last Post
Replies
2
Views
2K
Top