Consider the acid dissociation behavior of carbonic acid, H2CO3 . A p H gradient from 0 to 14 is given. Below a p H equal to p K a 1 which is 6.351, the predominant form is H 2 C O 3. Above a p H equal to p K a 2 which is 10.329, the predominant form is C O 3 2 minus. Between the two p K a values, the predominant form is H C O 3 minus. What is the predominant species present at pH 7.68 ? H2CO3 CO2−3 HCO−3 Calculate the ratio [CO2−3][HCO−3] at pH 9.80 .