Question

The sum of $pH$ and $pK_{b}$ for a basic buffer solution is 13. The ratio of the concentration of the base to that of the salt is

• A. 10
• B. 1
• C. 0.05
• D. 0.1
• E. 20

Answer 1

Answer: (D)

From $ pOH = p K_{b}-\log \frac{[\text { base }]}{[\text { salt }]}$

$14- pH = pK _{b}-\log \frac{[ base ]}{[ salt ]}$

$\therefore \, 14= pH + pK _{b}-\log \frac{[\text { base }]}{[\text { salt }]} $

or $ 14=13-\log \frac{[\text { base }]}{[ salt ]}$

$\log \,\frac{[\text { base }]}{[\text { salt }]}=13-14=-1$

$\therefore \, \frac{[\text { base }]}{[\text { salt }]}=$ antilog $(-1)=0.1$