127. Solving a chemistry problem

18d. In the absence of a standard solution of silver nitrate in the laboratory, the determination of the halide ion in the analyzed solution of sodium salt was carried out using a strongly basic anion exchanger AV-17 in the OH form.
An aliquot of the analyzed solution with a volume of V(X) was passed through a chromatographic column with an anion exchanger in the OH form, and after washing the column with water, the collected eluate was titrated with a solution of hydrochloric acid with a molar concentration of c(HC1), while spending V(HC1) ml of the titrant solution.
Write the equation for the ion exchange reaction between the anion exchange resin (R-OH) and the analyzed solution passed through the anion exchange resin, in molecular and ionic form. Using the data below, calculate the titer (g/ml) of the halide ion in the analyzed solution.
Why is it not recommended to use the above method when analyzing solutions containing halides of metals such as aluminum and magnesium?
Halide ion Br
V(X), ml 5.00
c(HC1), mol/l 0.09315
V(HC1), ml 10.22