The acid is diprotic; the more acidic hydrogen is the one on the 6-membered ring, and the second hydrogen is on the 5-membered ring.
12.
Being diprotic, carbonic acid has two acid dissociation constants, the first one for the dissociation into the bicarbonate ( also called hydrogen carbonate ) ion ( HCO 3 " ):
13.
"' Ethanedisulfonic acid "'is a diprotic sulfonic acid, with pKa values of-1.46 and-2.06, making it a very strong acid.
14.
Most often, the carbonate system is plotted, where the polyprotic acid is carbonic acid ( a diprotic acid ), and the different species are carbonic acid, carbon dioxide, bicarbonate, and carbonate.
15.
Suppose I was given Ba ( OH ) 2 at 0.5 M / L and was asked to find it's pOH . Since it's diprotic, I have to multiply the concentration by 2 right?
16.
A diprotic acid with two equivalent acidic sites, for example, if the interaction between the two sites were negligible, would be more acidic than a similar monoprotic acid by 0.3 pKa units just for statistical reasons ( 0.3 ~ log 2 ).
17.
The five-membered ring also possesses a keto group ( in the 8 position ), flanked by two secondary amino groups ( in the 7 and 9 positions ), and deprotonation of one of these at high pH could explain the p " K " 2 and behavior as a diprotic acid.
18.
This end-point is not sharp and is typical of a diprotic acid whose buffer regions overlap by a small amount : p " K " a2 " p " K " a1 is about three in this example . ( If the difference in p " K " values were about two or less, the end-point would not be noticeable . ) The second end-point begins at about pH 6.3 and is sharp.
