A buffer solution contains 0.40 mol of ammonium hydroxide and 0.50 mol of ammonium chloride to make a buffer solution of 1 L. Calculate the pH of the resulting buffer solution. Dissociation constant of ammonium hydroxide at 25^(@)C is 1.81xx10^(-5).

A buffer solution contains 0.40 mol of ammonium hydroxide and 0.50 mol

1.	A buffer solution contains 0.40 mol of ammonium hydroxide and 0.50 mol of ammonium chloride to make a buffer solution of 1 L. Calculate the pH of the resulting buffer solution. Dissociation constant of ammonium hydroxide at 25^(@)C is 1.81xx10^(-5).
Answer» SOLUTION :`pOH = pK_(b) + log. (["Salt"])/(["Base"])=pK_(b) + log. ([NH_(4)Cl])/([NH_(4)OH])` `[NH_(4)OH]=0.40` mol `L^(-1)` `[NH_(4)Cl]=0.50 ` mol `L^(-1)` `pK_(b) = - log K_(b) = - log (1.81 xx 10^(-5))=5-0.2577 = 4.7423` `:. pOH = 4.742 + log. (0.5)/(0.4)= 4.742+ log 1.25 = 4.742 + 0.0969 = 4.8389 ~= 4.839` `:. PH = 14-pOH = 14 - 4.839 = 9.161`.