A weak acid HA has degree of dissociation x. Which option gives the correct expression of (\(\mathrm{pH}-{\mathrm{pk}}_{…
A weak acid HA has degree of dissociation x. Which option gives the correct expression of (\(\mathrm{pH}-{\mathrm{pk}}_{\mathrm{b}}\))
(Memory-based Question 28/ Jan/25 morning shift )
\(\log \left(\frac{x}{1-x}\right)\)
\(\mathrm{HA}(\mathrm{aq})⇌{\mathrm{H}}^{+}(\mathrm{aq})+{\mathrm{A}}^{-}(\mathrm{aq})\\ \mathrm{C}--\\ \mathrm{C}-\mathrm{Cx}\mathrm{Cx}\mathrm{Cx}\\ {\mathrm{K}}_{\mathrm{a}}=\frac{\left[{\mathrm{H}}^{+}\right]\left[{\mathrm{A}}^{-}\right]}{\mathrm{HA}}=\frac{\mathrm{Cα}\times \mathrm{Cα}}{\mathrm{C}(1-\mathrm{x})}\\ \left[{\mathrm{H}}^{+}\right]=\mathrm{Cα}=\frac{{\mathrm{K}}_{\mathrm{a}}(1-\mathrm{x})}{\mathrm{x}}\\ \mathrm{pH}=-\log \left[{\mathrm{H}}^{+}\right]=-\log \frac{\left[{\mathrm{K}}_{\mathrm{a}}(1-\mathrm{x})\right]}{\mathrm{x}}\\ \mathrm{pH}={\mathrm{PK}}_{\mathrm{a}}-\log \frac{(1-\mathrm{x})}{\mathrm{x}}\\ \mathrm{pH}-{\mathrm{PK}}_{\mathrm{a}}=\log \frac{\mathrm{x}}{1-\mathrm{x}}\)
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