Topic: buffer capacity of Na3PO4 and HCl solution (Read 9357 times)

penguin_nguyen · « **on:** October 12, 2011, 03:54:37 AM »

First, I'm sorry because I'm not a foreign student my english is not good
I have a big problem with this exercise when i study analytical chemistry. Could you help me?
The concentration of HCl solution when mixed 150ml that solution with 100 mL Na3PO4 0,2M to get a pH of 7.21. The buffering capacity of the solution
H3PO4 pka1=2,15 ; pka2 = 7,21; pka3 = 12,32
I don't know which reactions happen when we put HCl into Na3PO4

AWK · « **Reply #1 on:** October 12, 2011, 08:59:17 AM »

Hcl is a strong acid, PO₄^3- and HPO₄^- are weak bases. What will happen when you mix acid with base?

penguin_nguyen · « **Reply #2 on:** October 13, 2011, 03:28:02 AM »

I'm not sure.I think that may be there are two reactions.
Na2HPO4 ----> 2Na+ + HPO4(2-) and HPO4(2-) + H3PO4 ----> 2H2PO4-
Can you help me!?

Borek · « **Reply #3 on:** October 13, 2011, 07:20:46 AM »

Neither of the reactions you wrote contains PO₄^3- as a reactant. You are looking for

PO₄^3- + H⁺ -> ...

Topic: buffer capacity of Na3PO4 and HCl solution (Read 9357 times)

penguin_nguyen

buffer capacity of Na3PO4 and HCl solution

AWK

Re: buffer capacity of Na3PO4 and HCl solution

penguin_nguyen

Re: buffer capacity of Na3PO4 and HCl solution

Borek

Re: buffer capacity of Na3PO4 and HCl solution

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