1) The titration of 0.50 M NH3 with 0.50 M HCL results in a final endpoint and a concentration of 0.25 M NH4 Cl with essentially all the NH3 complete conversion to NH4^+ . The Kb of NH3 is 1.8 x10^-5, and the Kw is 1x10^-14.
Use the Ka of NH4 to estimate the pH at the endpoint of this titration.