pKA=pH when:: (A) Solute is completely ionised, (B) When the concentration of ionised and unionized form is same, (C) Solute is completely unionized, (D) All of the above
Answer is B. Ans. B. When the concentration of ionized and unionized form is sameThis question is an application of Henderson Hasselbalch equation.It ispH=pKa+log/ is concentration of ionised form is concentration of unionised form.When =, thenpH=pKa+log/pH=pKa+log1i.e.pH=pKa+0