Equilibrium - Result Question 37
####39. Following solutions were prepared by mixing different volumes of $NaOH$ and $HCl$ of different concentrations :
[2018] a. $\quad 60 mL \frac{M}{10} HCl+40 mL \frac{M}{10} NaOH$ b. $55 mL \frac{M}{10} HCl+45 mL \frac{M}{10} NaOH$ c. $\quad 75 mL \frac{M}{5} HCl+25 mL \frac{M}{5} NaOH$ d. $100 mL \frac{M}{10} HCl+100 mL \frac{M}{10} NaOH$
$pH$ of which one of them will be equal to 1 ?
(a) $b$
(b) a
(c) $c$
(d) d
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Solution:
- (c) Meq. of $HCl=75 \times \frac{1}{5} \times 1=15$
Meq. of $NaOH=25 \times \frac{1}{5} \times 1=5$
Meq. of $HCl$ in resulting solution $=10$
Molarity of $[H^{+}]$in resulting mixture $=\frac{10}{100}=\frac{1}{10}$
$pH=-\log [H^{+}]=-\log [\frac{1}{10}]=1.0$
