Glycine has two ionizable groups, a carboxyl group and an amino group. Calculate the fraction of glycine that has its amino group protonated at pH 8.6. The pKa values for glycine are pK1 = 2.34 (carboxyl group) and pK2 (amino group) = 9.60.

0.9

Explanation:

Considering the Henderson - Hasselbalch equation for the calculation of the pH of the buffer solution as:

pH=pKa+log[base]/[acid]

Given that:

pH = 8.6

pK2 will be used for the amino group which is = 9.60

So,

8.60=9.60+log[base]/[acid]

log[base]/[acid]=1.0

[base]/[acid] = 10

So,

[base] = 10 [acid]

Fraction is:

[base] / ([base] + [acid]) = 10 [acid] / 10 ([acid] + [acid]) = 10 / 11 = 0.9