Chapter 4 - Sections 4.1-4.9 - Exercises - Problems by Topic - Page 189: 87

$0.1810\,M\,HClO_{4}$

When the equivalence point is reached, Moles of titrant= moles of the unknown solution That is, $M_{1}V_{1}= M_{2}V_{2}$ $\implies 0.2000M\times22.62\times10^{-3}L=M_{2}\times 25.00\times10^{-3}L$ $\implies M_{2}=\frac{0.2000M\times22.62}{25.00}$=0.1810 M