In the precipitation of the iron group in qualitative analysis, ammonium chloride is added before adding ammonium hydroxide to

Options

A. Decrease concentration of `OH^(-)` ions
B. Prevent interference by phosphate ions
C. Increase concentration of `Cl^(-)` ions
D. Increase concentration of `NH_(4)^(+)` ions

Answer

A

Explanation

As `NH_(4)Cl` is a strong electrolyte. It suppresses the ionization of `NH_(4)OH`, so the concentration of `OH^(-)` ions in the solution is decreased, but it is sufficient to precipitate the III group basic radicals because the solubility product of III group hydroxides is lower than IV,
V and VI group hydroxides as