Question

A 11.1 g sample of an aqueous solution of perchloric acid contains an unknown amount of the acid. If 29.9 mL of 0.534 M sodium hydroxide are required to neutralize the perchloric acid, what is the percent by mass of perchloric acid in the mixture?

Answer 1

$HClO_4 + NaOH → NaClO_4 + H_2O$

By using Molarity equation,

$M_1V_1=M_2V_2$ (1 for Acid,2 for NaOH)

Let $x$ be mole fraction of $HClO_4$ in the solution.

Molar mass of perchloric acid$=100.5\ gm$

So,$\frac{11.1}{100.5}\times x=29.9\times 10^{-3}\times 0.534$

$x=0.144563$

Mass percentage$=x\times 100=14.46$ %