The most simple property to calculate this is Ka*Kb=e-14 -->Ka=(e-14)/Kb Ka for NH4+: Kb of NH3=(1.8e-5) --> Ka=(e-14)/(1.8e-5)=5.56e-10 Ka for CH3NH3+: Kb for CH3NH2=4.4e-4 --> Ka=(e-14)/(4.4e-4)=2.27e-11 Kb for F-: Ka for HF=6.8e-4 --> Kb=(e- 14)/(6.8e-4)=1.47e-11 Solution The most simple property to calculate this is Ka*Kb=e-14 -->Ka=(e-14)/Kb Ka for NH4+: Kb of NH3=(1.8e-5) --> Ka=(e-14)/(1.8e-5)=5.56e-10 Ka for CH3NH3+: Kb for CH3NH2=4.4e-4 --> Ka=(e-14)/(4.4e-4)=2.27e-11 Kb for F-: Ka for HF=6.8e-4 --> Kb=(e- 14)/(6.8e-4)=1.47e-11.