Question

How many moles of sulphuric acid must be dissolved to produce 250 mL of an aqueous solution of $pH=3.52$? Assume complete dissociation.

• A. $3.75\times {10}^{-5}$
• B. $7.5\times {10}^{-4}$
• C. $3.75\times {10}^{-4}$
• D. $7.5\times {10}^{-5}$

Answer 1

The correct option is D $7.5\times {10}^{-5}$

$p^H=-\log \left[H^{+}\right]$

$\Rightarrow \left[H^{+}\right]={10}^{-3.52}$

$\Rightarrow \left[H^{+}\right]=3.02\times {10}^{-4}$

$\Rightarrow$ Concentration= $\frac{n}{v}$

$\Rightarrow 3.02\times {10}^{-4}=\frac{n\times 1000}{250\left(L\right)}$

$\Rightarrow n=7.5\times {10}^{-5}$ moles