Question

Give chemical equations for the following conversion:-
Ammonia changes to brown gas.

Answer 1

As we know that ammonia is a colourless gas which is a stable binary hydride. It is a compound of nitrogen and hydrogen and its chemical formula is $N{{H}_{3}}$. It also shows various reactions and leads to the production of different important compounds. So here we have written the reaction of ammonia which produces brown gas.

Complete answer:
Let us discuss about ammonia followed by reactions as follows:-
-Ammonia: It is the simplest pnictogen hydride that is a compound of nitrogen and hydrogen. Its chemical formula is $N{{H}_{3}}$. It has a distinct characteristic of a pungent smell. This chemical compound is a building block for the synthesis of many pharmaceutical products and is also used in production of many commercial cleaning products.
-When ammonia gas is combusted in the presence of particular catalyst following reaction takes place-
$4N{{H}_{3}}+5{{O}_{2}}\xrightarrow[{{800}^{\circ }}C]{Pt}4NO+6{{H}_{2}}O+Heat$
In the above reaction, we can see that ammonia gas is combusted in the presence of platinum (acts as a catalyst) and it yields nitric oxide along with water molecules and heat. This reaction takes place at very high temperature and also it is an exothermic reaction.
-Further nitric oxide gets combusted to form nitrogen dioxide as follows:-
$2NO+{{O}_{2}}\to 2N{{O}_{2}}$
This reaction takes place simultaneously as soon as nitric oxide is produced.
-At high temperatures, nitrogen dioxide is a brown colour gas and is used as an intermediate in most of the reactions like synthesis of nitric acid. It usually gets mixed in air by burning of fuel which further leads to acid rain.

Note:
-Remember that we can use platinum gauze or warm chromium (III) oxide as a catalyst in the conversion of ammonia to nitric oxide.
-It is very difficult to combust ammonia in the absence of a catalyst due to relatively low heat of combustion, high heat of vaporization, high auto-ignition temperature and very narrow flammability range.