- #1
4LeafClover
- 35
- 0
Question:
What is the pH of a solution made by mixing 0.30 mol NaOH, 0.25 mol Na2HPO4, and 0.20 mol H3PO4 with water and diluting to 1.00L?
My work:
So I found that the Ka value of H3PO4 is 7.5*10^-3 and the Ka value of HPO4 (found in Na2HPO4) is 4.2*10^-13. Because Ka of HPO4 is so small, I know that it won't contribute much to the concentration of H+, but don't I still need to consider it when figuring out the pH? Or can I just drop it and do my calculations like I am working only with H3PO4?
I also know that since we are working with 1L of solution, the number of moles of each molecule used is equivalent to that molecule's molarity.
Other than that, I am stumped because of the two Ka values. Anyone know how to work this problem
What is the pH of a solution made by mixing 0.30 mol NaOH, 0.25 mol Na2HPO4, and 0.20 mol H3PO4 with water and diluting to 1.00L?
My work:
So I found that the Ka value of H3PO4 is 7.5*10^-3 and the Ka value of HPO4 (found in Na2HPO4) is 4.2*10^-13. Because Ka of HPO4 is so small, I know that it won't contribute much to the concentration of H+, but don't I still need to consider it when figuring out the pH? Or can I just drop it and do my calculations like I am working only with H3PO4?
I also know that since we are working with 1L of solution, the number of moles of each molecule used is equivalent to that molecule's molarity.
Other than that, I am stumped because of the two Ka values. Anyone know how to work this problem