In which volume ratio NH_(4)Cl and NH_(4)OH solutions (each 1 M ) should be mixedto get a buffer solution of pH 9.80 ? (pK_(b) "of" NH_(4)OH=4.74)

In which volume ratio NH_(4)Cl and NH_(4)OH solutions (each 1 M ) shou

1.	In which volume ratio NH_(4)Cl and NH_(4)OH solutions (each 1 M ) should be mixedto get a buffer solution of pH 9.80 ? (pK_(b) "of" NH_(4)OH=4.74)
Answer» `1:2.5` `2.5:1` `1:3.5` `3.5:1` Solution :SUPPOSE `V_(1) ` mL of 1 M `NH_(4)Cl` solution is MIXED with `V_(2)` mL of 1 M `NH_(4)OH` solution . `V_(1)` mL of 1 M `NH_(4) Cl = V_(1)` millimole `V_(2)` mL of 1 M `NH_(4)OH=V_(2)` millimole `V_(2)` mL of 1 M `NH_(4) OH = V_(2)` millimole pH = 9.80. Hence, pOH = 14 - 9.80 = 4.20 Now, pOH = `pK_(b) + log .(["Salt"])/(["Base"])` `:.4.20 = 4.74 + log .(V_(1))/(V_(2))` or `log. (V_(1))/(V_(2))= - 0.54 = BAR(1) . 46 :. (V_(1))/(V_(2))=0.29 = (1)/(3.5)`