Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: jcais on July 13, 2006, 11:04:48 PM
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Hello,
I won't be able to see the teacher until next week. I took a test and got only this problem wrong so it is on my mind. It was
What is the conjugate acid of HPO4-2?
I put H+ because isn't it:
(HPO4)2- (PO4)3- + H+ in the 3rd ionization?
Maybe I am missing something. Can someone please help me?
Thank you. ???
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I think the question is probably referring to
HPO42- + H3O+ <-----> H2PO4- + H2O
ie, HPO42- is acting as a base rather than an acid.
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What is the conjugate acid of HPO4-2?
an example:
H3PO4 + H2O <--> H2PO4- + H3O+
now we can say that H2PO4- is the conjugated base of H3PO4 and on the other hand we can say that H3PO4 is the conjugated acid of H2PO4-
the definition for the conjugated acid: the acid that will be formed when the base dissociates. Thus in the previous example:
H2PO4- + H2O --> H3PO4 + OH-
but it's actually the same.
now it should be no problem to answer this question ;)