Question

There are two bottles X and Y. One bottle has ammonium hydroxide, whereas the other has sodium hydroxide. How will you differentiate both?

Answer 1

Reagent bottles X and Y can be identified by using calcium salts such as Ca(NO₃)₂.

When NaOH is added to Ca(NO₃)₂, Ca(OH)₂ precipitates as a white precipitate that is sparingly soluble in excess of NaOH.

\[\ce{Ca(NO3)2 + 2NaOH -> Ca(OH)2 + 2NaNO3}\]

Whereas, on addition of NH₄OH to calcium salts, no precipitation of Ca(OH)₂ occurs even with an excess of NH₄OH because the concentration of OH⁻ions from the ionization of NH₄OH is so low that it cannot precipitate the calcium hydroxide.

So the reagent bottle which gives white precipitate is NaOH and the other is NH₄OH.