Question

$40\, ml$ of $0.1\, M$ ammonia solution is mixed with $20 \,ml$ of $0.1\, M\, HCl$. What is the $pH$ of the mixture? $\left( p K_{b}\right.$ of ammonia solution is $\left.4.74\right)$

• A. 4.74
• B. 2.26
• C. 9.26
• D. 5

Answer 1

Answer: (C)

9.26

Answer 2

Handerson-Hasselbalch equation $pOH = pK _{ b }+\log \frac{[ \text{salt} ]}{[\text { base }]}$ At half stage of titration $[$ salt $]=[$ base $]$ as $pOH = pK _{ b }=4.74$ $pH =14- pOH =14-4.74=9.26$