You are a scientist at a reputable lab researching how different polyprotic acids affect the pH of a solution. How many equivalence points would be visible on the titration curve if you fully titrated a given a solution of 1.0 M sulfurous acid (H2SO3)?
For a polyprotic acid having more than 1 ionizable hydrogens in it, the pH value changes according to the ionization constant. So the first equivalence point or loss of first H gives a pH below 7. The solution would be acidic. When it looses the second H, the solution becomes basic due to hydrolysis of salt formed and generation of OH- in solution. The pH at second equivalence point would be greater than 7.
For the titration of 1.0 M H2SO3 with base, we would see two equivalence points corresponding to the to H's losses from the acid. It is important to mention here that for polyprotic acid, the Ka1 > Ka2 and thereafter.
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