Derive an expression for the hydrolysis constant and degree of hydrolysis of salty ofstrong acid and weak base.

Derive an expression for the hydrolysis constant and degree of hydroly

1.	Derive an expression for the hydrolysis constant and degree of hydrolysis of salty ofstrong acid and weak base.
Answer» Solution :Hydrolysis of salt of strong acid and weak base : Let us consider the reactions between a strong acid, HCI, and a weak base, `NH_4OH`, to produce a salt, `NH_4CI`, and water `HCI_((aq))+NH_4OH_((aq)) hArr NH_4 CI_((aq))+H_2 O (I)` `NH_4 CI_((aq)) to NH_(4)^(+)+CI_((aq))^(-)` `NH_4^+`is a strong conjugate acid of the weak base `NH_4OH` and it has a tendency to react with `OH^-` from water to produce unionised `NH_4OH` shown below. `NH_(4(aq))^(+)+H_2O(I) hArr NH_4OH_((aq))+H_((aq)^+` There is no such tendency shown by `CI^-` and THEREFORE `[H^+] gt [OH^-]`, the solution is acidic and the PH is less than 7. As discussed in the salt hydrolysis of strong base and weak acid. In this case also, we can establish a relationship between the `K_(h) and K_(b)` as `k_(h).K_(b)=K_(w)` Let us calculate the `K_(h)` value in terms of degree of hydrolysis (h) and the concentration of salt `K_(h)=h^2 C and [H^+]=sqrt(K_(h).C)` `[H^+]=sqrt((K_w)/(K_b).C)` `pH=-log[H^+]` `=-log((K_w.C)/(K_b))^(1/2)` `=-(1)/(2)logK_w-(1)/(2)logC+(1)/(2)logK_(b)` `pH=7-(1)/(2)pK_(b)-(1)/(2)logC.`