Ephedrine , a central nervous stimulant, is used in nasal sprays as decongestant. This compound is a weak organic base:
C10H15ON(aq) + H2O(l) <--> C10H15NOH+(aq) +OH-(aq)
Kb has the value of 1.4 x 10-4. What pH would you expect for 0.035 M solution of ephedrine, assuming that no other substances are present? What is the value of pKa for the conjugate acid of ephedrine?