question_answer 1)

The pH of 0.004 M hydrazine solution is 9.7. Calculate its ionization constants \[{{K}_{b}}\]and \[p{{K}_{b}}\] .

Answer:

\[{{N}_{2}}{{H}_{4}}+{{H}_{2}}O\rightleftharpoons {{N}_{2}}H_{5}^{+}+O{{H}^{-}}\] \[pOH=14-9.7=4.3\] \[[O{{H}^{-}}]=Antilog(-4.3)=5.01\times {{10}^{-5}}M\] \[[O{{H}^{-}}]=\sqrt{C{{K}_{b}}}\] \[5.01\times {{10}^{-5}}=\sqrt{0.004\times {{K}_{b}}}\] \[{{K}_{b}}=6.27\times {{10}^{-7}}\] \[p{{K}_{b}}=-\log (6.27\times {{10}^{-7}})=6.2\]