Polyprotic acid vs base dissociation

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Arya Bhalla 1H
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Polyprotic acid vs base dissociation

Postby Arya Bhalla 1H » Tue Jan 18, 2022 9:07 am

When H2SO4 dissociates do we assume that it loses both H+ at once or that it loses 1 H+ and then HSO4- later loses another H+. I'm asking because for the bases like BaOH2, it loses both OH- at the same time. How come H2SO4 only loses 1 H+ as a strong acid and then functions as a weak acid when it loses the second H+ but BaOH2 loses both OH- at once as a strong base?

Alison King 3L
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Re: Polyprotic acid vs base dissociation

Postby Alison King 3L » Tue Jan 18, 2022 1:38 pm

I think that we treat the first dissociation as a strong acid, so it completely loses the first H+, but for the second dissociation we treat it as a weak acid and use an ICE table and the Ka to calculate the second H+, then add the two H+ concentrations from the two dissociations to get the total [H+]

Kaira Shibata 1E
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Re: Polyprotic acid vs base dissociation

Postby Kaira Shibata 1E » Tue Jan 18, 2022 4:00 pm

H2SO4 is a special case because it can lose the first H+ and become HSO4- which is amphiprotic. In this case, you would assume that it is a strong acid when it dissociates to become H+ and HSO4-.


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