Answer: 7
Explanation:
The volume of 0.18 M HClO4 is 100.0 mL.
Calculate the number of moles of 0.18 M HClO4 and 0.27 M LiOH as shown below:
[tex]$Number of moles $=$ Concentration $\times$ Volume$\begin{aligned}\text { Number of moles of } \mathrm{HClO}_{4} &=100.0 \mathrm{~mL} \times\left(\frac{1 \mathrm{~L}}{1000 \mathrm{~mL}}\right) \times\left(\frac{0.18 \mathrm{~mol}}{\mathrm{~L}}\right) \\&=0.018 \mathrm{~mol} \\\text { Number of moles of } \mathrm{HClO}_{4} &=66.67 \mathrm{~mL} \times\left(\frac{1 \mathrm{~L}}{1000 \mathrm{~mL}}\right) \times\left(\frac{0.27 \mathrm{~mol}}{\mathrm{~L}}\right) \\&=0.018 \mathrm{~mol}\end{aligned}$[/tex]
[tex]$Moles of both acid aand base are equal.\\ $\mathrm{HClO}_{4}$ is a strong acid and $\mathrm{LiOH}$ is a strong base.[/tex]
At the equivalence point, the number of moles of the acid completely reacted with all the moles of the added base. Thus, the solution becomes neutral in nature. The pH of a neutral solution is 7. Therefore, the pH of the solution at the equivalence point is 7.
