Strengths of oxoacids

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Kelsey Ouyang 3H
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Strengths of oxoacids

Postby Kelsey Ouyang 3H » Mon Nov 30, 2015 9:51 am

According to the textbook and course reader, we know that the greater the number of oxygen atoms attached to the central atom, the stronger the acid for oxoacids. However, for textbook problem #12.35 it is given that H3PO3 (phosphorous acid)has a lower pKa value of 2.00 compared to the pKa value of H3PO4 (phosphoric acid) which is 2.12. Therefore, H3PO3 has a higher Ka value and is a stronger acid. This makes me confused because in this hw problem, we see that H3PO3 and H3PO4 do not follow the trend. Is there something that I am missing?

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Re: Strengths of oxoacids

Postby Chem_Mod » Tue Dec 01, 2015 11:16 am

This is just an exception to the general trend.

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