4.5 Exercise 4

In a common medical laboratory determination of the concentration of free chloride ion in blood serum, a serum sample is titrated with a Hg(NO₃)₂ solution.
$2 \text{Cl}^{−} \left(a q\right) + \text{Hg} \left(\text{NO}_{3}\right)_{2} \left(a q\right) \rightarrow 2 \text{NO}_{3} ^{−} \left(a q\right) + \text{HgCl}_{2} \left(s\right)$

What is the Cl⁻ concentration in a 0.25-mL sample of normal serum that requires 1.46 mL of 8.25 $\times$ 10⁻⁴ M Hg(NO₃)₂(aq) to reach the end point?