Comment on the relative acidities of h3po4 and the h2po4 ion?
I don't understand what this question is asking? Would H3PO4 is a strong acid and will completely dissociate into ions in aqueous solution suffice?
H3PO4 would readily donate a proton in solution compared to H2PO4. I think that would suffice.
Note that H3PO4 is NOT a strong acid and does NOT ionize completely in solution.
No, the question is asking about the relative acidities of H3PO4 (phosphoric acid) and the H2PO4- ion (dihydrogen phosphate ion). The relative acidities refer to their ability to donate protons (H+) in an aqueous solution.
H3PO4 is a triprotic acid, meaning it can donate three protons sequentially. In its first dissociation step, it donates one proton to form the H2PO4- ion. In the second dissociation step, H2PO4- donates another proton to form the HPO42- ion (monohydrogen phosphate ion). And finally, in the third dissociation step, HPO42- donates its last proton to form the PO43- ion (phosphate ion).
The relative acidities can be assessed by looking at their dissociation constants (Ka values). The Ka values for H3PO4, H2PO4-, and HPO42- decrease progressively, indicating a decrease in acid strength with each deprotonation step. Therefore, H3PO4 is the strongest acid among the three species, followed by H2PO4-, and HPO42-.
In conclusion, H3PO4 is more acidic than the H2PO4- ion.
The question is asking you to compare the relative acidities of two species: H3PO4 (phosphoric acid) and H2PO4- (dihydrogen phosphate ion).
To determine the relative acidities, we need to consider how readily these species donate protons (H+) in aqueous solution.
H3PO4 is a triprotic acid, meaning it can donate three protons sequentially. In the first dissociation step, it forms the H2PO4- ion:
H3PO4 ⇌ H+ + H2PO4-
In the second dissociation step, H2PO4- can further donate a proton to form HPO42- (hydrogen phosphate ion):
H2PO4- ⇌ H+ + HPO42-
Finally, in the third dissociation step, HPO42- loses another proton to form PO43- (phosphate ion):
HPO42- ⇌ H+ + PO43-
Comparing H3PO4 and H2PO4-, we can say that H3PO4 is a stronger acid because it readily donates its first proton to form H2PO4-. Once the first proton is donated, H2PO4- is a weaker acid compared to H3PO4.
In summary, H3PO4 is a strong acid as it can donate three protons while H2PO4- is a weaker acid as it can only donate two protons.