Question

How many compounds liberate $N{{H}_{3}}$ on heating from the following?
\[{{(N{{H}_{4}})}_{2}}S{{O}_{4}},{{(N{{H}_{4}})}_{2}}C{{O}_{3}},N{{H}_{4}}Cl,N{{H}_{4}}N{{O}_{3}},{{(N{{H}_{4}})}_{2}}C{{r}_{2}}{{O}_{7}}\]

Answer 1

Hint: The molecular formula of ammonia is $N{{H}_{3}}$ . Generally ammonium derivatives mean ammonium salts liberate ammonia on heating. All ammonium salts won’t release ammonia on heating. Ammonia is gaseous in nature at room temperature.

Complete step by step solution:
- In the question it was asked to find which compound releases ammonia gas on heating.
- The given compounds are
Ammonium sulphate - ${{(N{{H}_{4}})}_{2}}S{{O}_{4}}$
Ammonium carbonate - ${{(N{{H}_{4}})}_{2}}C{{O}_{3}}$
Ammonium chloride - $N{{H}_{4}}Cl$
Ammonium nitrate- $N{{H}_{4}}N{{O}_{3}}$
Ammonium chromate - ${{(N{{H}_{4}})}_{2}}C{{r}_{2}}{{O}_{7}}$
- Ammonium sulphate on heating produces the following compounds.
\[{{(N{{H}_{4}})}_{2}}S{{O}_{4}}\xrightarrow{heat}2N{{H}_{3}}+{{H}_{2}}S{{O}_{4}}\]
- Ammonium carbonate on heating produces the following compounds.
\[{{(N{{H}_{4}})}_{2}}C{{O}_{3}}\xrightarrow{heat}2N{{H}_{3}}+{{H}_{2}}O+C{{O}_{2}}\]
- Ammonium chloride on heating produces the following compounds.
\[N{{H}_{4}}Cl\xrightarrow{heat}N{{H}_{3}}+HCl\]
- Ammonium nitrate on heating produces the following compounds.
\[N{{H}_{4}}N{{O}_{3}}\xrightarrow{heat}{{N}_{2}}O+2{{H}_{2}}O\]
- Ammonium chromate on heating produces the following compounds.
\[{{(N{{H}_{4}})}_{2}}C{{r}_{2}}{{O}_{7}}\xrightarrow{heat}{{N}_{2}}+C{{r}_{2}}{{O}_{3}}+4{{H}_{2}}O\]
- From the above reaction we can see clearly only few compounds are releasing ammonia as a product of heating.
- The compounds which are liberating ammonia on heating are Ammonium carbonate, Ammonium chloride and ammonium sulphate.
- But there is a small issue with ammonium sulphate, on heating ammonium sulphate produces ammonia but again the formed ammonia reacts with ammonia and produces back the original compound ammonium sulphate.
\[{{(N{{H}_{4}})}_{2}}S{{O}_{4}}\rightleftarrows 2N{{H}_{3}}+{{H}_{2}}S{{O}_{4}}\]
- It is a reversible reaction. That is why ammonium sulphate is not used in the preparation of ammonia.

Note: Ammonia is a good fertilizer to the crops. Plants or trees cannot digest nitrogen which is available in the atmosphere because the nitrogen atoms in nitrogen molecules are bonded together with triple bonds. It is very difficult to break the triple bond by the plants. That is why ammonia should be supplied to crops as a nitrogen source.