using the hasselbach-Handerson equation calculate the fraction of asprin Pka is 5.6 and PH is 8.6?
Do you want the fraction [A-]/[HA] dissociated?
[Your value for the pKa for aspirin is low from memory =about 3.5??]
From the H-H equation
pH=pKa+log([A-]/[HA])
8.6=5.6 + log([A-]/[HA])
3.0=log([A-]/[HA])
so
10^+3 = [A-]/[HA]