Calculate the volume of 0.1 M acetic acid solution to be mixed with 50cm^(3) of 0.2M sodium acetate solution, in order to prepare a standard buffer of pH 4.94 (pK_(a) of acetic acid = 4.74).

Calculate the volume of 0.1 M acetic acid solution to be mixed with 50

1.	Calculate the volume of 0.1 M acetic acid solution to be mixed with 50cm^(3) of 0.2M sodium acetate solution, in order to prepare a standard buffer of pH 4.94 (pK_(a) of acetic acid = 4.74).
Answer» SOLUTION :`pH=pK_(a)+"log"(["salt"])/(["acid"])` `4.94=4.74+"log"(["salt"])/(["acid"])` `"log"(["salt"])/(["acid"])=4.94-4.74=0.20` `(["salt"])/(["acid"])="ANTI"log0.20=1.58` That is, the ratio of concentrations of salt : acid is 1.58 : 1 Let V be VOLUME of 0.1 M acetic acid to be mixed `therefore(["salt"])/(["acid"])=((50xx2)/(1000))/((Vxx0.1)/(1000))=(1.58)/(1)` `therefore` Volume of acetic acid, `V=(50xx0.2xx1)/(0.1xx1.58)=90.4cm^(3)`.