polyprotic acids

[Elizabeth Harty 1A]

Why is it that the Ka is bigger for the first dissociation in comparison to the second?

[Joowon Seo 3A]

Because it is easier for the first hydrogen to be dissociated from the acid. The atom holds on to the second and the third protons more tightly than the first.

[Adam Kramer 1A]

When you get rid of the first proton, there is more of a negative charge, holding the rest of the protons in a stronger bond, therefore making it harder to dissociate. This makes it take more energy to break the bond and therefore makes the Ka smaller for each successive dissociation.

[rohun2H]

The negative charge created after the first dissociation makes it more difficult for the second dissociation to occur.

[Libby Dillon - 1A]

The Ka value for the first reaction does not involve any negatively charged ions in the example we did during lecture. This means the proton is not as tightly held as it will be in the second reaction, which involves a negatively charged ion. The proton will be more tightly held in the second reaction and the Ka2 value will be lower.

[DMaya_2G]

The first proton to dissociate is the most strongly acidic, followed by the order in the next most strongly acidic proton.