A buffer solution with pH 9 is to be prepared by mixing NH_(4) Cl and NH_(4)OH. Calculate the number of moles of NH_(4)Cl that should be added to one litre of 1.0 M NH_(4)OH (K_(b)=1.8xx10^(-5))

A buffer solution with pH 9 is to be prepared by mixing NH_(4) Cl and

1.	A buffer solution with pH 9 is to be prepared by mixing NH_(4) Cl and NH_(4)OH. Calculate the number of moles of NH_(4)Cl that should be added to one litre of 1.0 M NH_(4)OH (K_(b)=1.8xx10^(-5))
Answer» Solution :For a BASIC BUFFER, `pOH = pK_(b)+log.(["SALT"])/(["Base"])` Further, `pH + pOH = 14 ` so that `pOH = 14 - pH = 14 - 9 = 5` `pK_(b)=-log K_(b) = - log(1.8xx10^(-5))=4.7447` [Base] `=[NH_(4)OH]= 1 "MOL" L^(-1)` `:. 5 = 4. 7447 + log. (["Salt"])/(1) or log ["Salt"] = 0.2553 or ["Salt"]= 1.8 "mol" L^(-1)`