Question

How many moles of HCl needs to be added to a solution containing 0.10 mol of NH3 to make a buffer of pH 9.26

Answer 1

Answer:

The correct solution is "0.05 mol".

Explanation:

According to the question,

⇒  $NH_{3}(aq)+HCL(aq)\rightarrow NH_{4}^+Cl^-(aq)$

       0.10             x                    0

    (0.10-x)          0                    x

Now,

$pH=pKa+log\frac{[NH_{4}Cl]}{[NH_{3}]}$

$9.26=9.26+log(\frac{x}{0.10-x} )$

$log(\frac{x}{0.10-x})=0$

$\frac{x}{0.10-x}=1$

$2x=0.10$

$x=0.05$ (moles of HCL needed)