Question

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

• A. Decrease concentration of $O{H}^{-}$ ions
• B. Prevent interference by phosphate ions
• C. Increase concentration of $C{l}^{-}$ ions
• D. Increase concentration of $N{H}_4^{+}$ ions

Answer 1

The correct option is A Decrease concentration of $O{H}^{-}$ ions

Option (A) is correct.
In the precipitation of the iron group in qualitative anlaysis, ammonium chloride is added before adding ammonium hydroxide to decrease concentration of $O{H}^{-}$ ions so that only $Fe$, $Cr$, and $Al$ are precipitated as their hydroxides.