Question

i)How soluble is ammonia in water?
ii)Give two reasons to show that the solution of ammonia in water contains hydroxide ions.
iii)Name a simple method you would employ to prepare ammonium salts in your laboratory.

Answer 1

1. Ammonia$\left({\mathrm{NH}}_3\right)$ gas is very soluble in water due to the presence of lone pairs at the nitrogen. This lone pair is attracted by hydrogen of water molecule due to hydrogen bonding. The presence of lone pair makes ammonia a polar compound In case of solubility polar molecules will dissolve in polar solvents. Here water and ammonia both are polar so solubility will be high.
   
2. (a) When ammonia$\left({\mathrm{NH}}_3\right)$ dissolves in water it forms ammonium hydroxide$\left({\mathrm{NH}}_4\mathrm{OH}\right)$ which is basic in nature so it turns red litmus into the blue.
   ${\mathrm{NH}}_{3_{\left(\mathrm{aq}\right)}}+{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{l}\right)}\iff \underset{\mathrm{basic}}{{\mathrm{NH}}_4{\mathrm{OH}}_{\left(\mathrm{aq}\right)}}$
   (b) When the solution of ammonia on water reacts with metals It precipitates hydroxides of metals.
   
3. Titration can be employed to prepare ammonium salts in your laboratory.