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Câu hỏi: Viết biểu thức hằng số phân li axit \({K_a}\) hoặc hằng số phân li bazo \({K_b}\) cho các trường hợp sau: \(HF, Cl{O^ - }, NH_4^ + , F^-.\)
Lời giải chi tiết
$HF \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over
{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} {H^ + } + {F^ - }$
Ta có \({K_a} = {{\left[ {{H^ + }} \right]\left[ {{F^ - }} \right]} \over {\left[ {HF} \right]}}\)
$Cl{O^ - } + {H_2}O \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over
{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} HClO + O{H^ - }$
Ta có \({K_b} = {{\left[ {HClO} \right]\left[ {O{H^ - }} \right]} \over {\left[ {Cl{O^ - }} \right]}}\)
$N{H_4}^ + + {H_2}O \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over
{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} N{H_3} + {H_3}{O^ - }$
Ta có \({K_a} = {{\left[ {N{H_3}} \right]\left[ {{H_3}{O^ +}} \right]} \over {\left[ {NH_4^ + } \right]}}\)
${F^ - } + {H_2}O \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over
{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} HF + O{H^ - }$
Ta có \({K_b} = {{\left[ {HF} \right]\left[ {O{H^ - }} \right]} \over {\left[ {{F^ - }} \right]}}\)
$HF \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over
{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} {H^ + } + {F^ - }$
Ta có \({K_a} = {{\left[ {{H^ + }} \right]\left[ {{F^ - }} \right]} \over {\left[ {HF} \right]}}\)
$Cl{O^ - } + {H_2}O \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over
{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} HClO + O{H^ - }$
Ta có \({K_b} = {{\left[ {HClO} \right]\left[ {O{H^ - }} \right]} \over {\left[ {Cl{O^ - }} \right]}}\)
$N{H_4}^ + + {H_2}O \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over
{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} N{H_3} + {H_3}{O^ - }$
Ta có \({K_a} = {{\left[ {N{H_3}} \right]\left[ {{H_3}{O^ +}} \right]} \over {\left[ {NH_4^ + } \right]}}\)
${F^ - } + {H_2}O \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over
{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} HF + O{H^ - }$
Ta có \({K_b} = {{\left[ {HF} \right]\left[ {O{H^ - }} \right]} \over {\left[ {{F^ - }} \right]}}\)