Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: penguin_nguyen on October 12, 2011, 03:54:37 AM
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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
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Hcl is a strong acid, PO43- and HPO4- are weak bases. What will happen when you mix acid with base?
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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!?
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Neither of the reactions you wrote contains PO43- as a reactant. You are looking for
PO43- + H+ -> ...