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6-2.Equilibrium-II (Ionic Equilibrium)
medium
An aqueous solution of $HCl$ has a $pH$ of $2.0$. When water is added to increase the $pH$ to $5.0$, the hydrogen ion concentration
Aremains the same
Bdecreases three-fold
Cincreases three-fold
Ddecreases thousand-fold
(KVPY-2010)
Solution
(d)
As we know
$pH =-\log \left[ H ^{+}\right]$
As the initial $pH$ of aqueous solution $=2$
$\therefore$ Concentration of $H ^{+},\left[ H ^{+}\right]=10^{-2}$
As the final $pH$ of aqueous solution $=5$
$\therefore \quad\left[ H ^{+}\right]=10^{-5}$
$\therefore \quad \frac{\left[ H ^{+}\right]_f}{\left[ H ^{+}\right]_i} =\frac{10^{-5}}{10^{-2}}$
$=10^{-3}$
Thus, $H ^{+}$concentration decreases by thousand fold.
As we know
$pH =-\log \left[ H ^{+}\right]$
As the initial $pH$ of aqueous solution $=2$
$\therefore$ Concentration of $H ^{+},\left[ H ^{+}\right]=10^{-2}$
As the final $pH$ of aqueous solution $=5$
$\therefore \quad\left[ H ^{+}\right]=10^{-5}$
$\therefore \quad \frac{\left[ H ^{+}\right]_f}{\left[ H ^{+}\right]_i} =\frac{10^{-5}}{10^{-2}}$
$=10^{-3}$
Thus, $H ^{+}$concentration decreases by thousand fold.
Standard 11
Chemistry
