achiever gchem

[utdent20]

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What is the conjugate base of H3PO4?
A. PO43- B. HPO42- C. H2PO4- D. H3O+ E. H2O

The answer is C but why.. I thought the conjugate base would have been PO4. I guess i am not really clear on what is conjugate acid... any explanations would help.. thanks!

 

[Commitment]

H3PO4(s) + H2O(l) ⇌ H3O+(aq) + H2PO4–(aq) Ka1= 7.5×10−3

H3PO4 is polyprotic meaning, it has more than one proton to shed off...

H2PO4- + H2O -> H30+ + HPO4 2minus... this too can make a conjugate base: PO4-...
thus, PO4- isnt the conjugate base of H3PO4

 

[utdent20]

so bascially whatever the substance is it will be one less Hydrogen in teh conjugate acid..???

 

[heatwheat]

so bascially whatever the substance is it will be one less Hydrogen in teh conjugate acid..???

Ya.