78% of atmosphere is covered by nitrogen gas. Gaseous nitrogen is not a reactive compound in room conditions. Nitrogen gas is prepared in laboratory scale and industrial scale for specific purposes. In this tutorial, we will discuss how to prepare Nitrogen gas in the laboratory in detail.
Liquid nitrogen is used as a coolant. Liquid nitrogen only exist between -2100C - -1960C. So you can see temperature of liquid nitrogen is very low.
Gaseous nitrogen is used as a filling agent in food industry because its reactivity characteristics are poor. There are more uses of nitrogen gases and they are explained in detail below.
There are several methodologies to prepare Nitrogen gas in the laboratory according to the availability of chemicals. Each those reactions with required other physical parameters are explained in detail here.
Ammonia is oxidized to nitrogen gas while oxygen gas is reduced. Chemical balanced equation of the respective reaction is mentioned above. Oxidation number of nitrogen atom in ammonia molecule is oxidized from -3 to 0.
Send ammonia gas through a hot copper oxide layer. Ammonia will oxidized to nitrogen gas and copper oxide is reduced to copper metal. Furthermore water vapor is given as other product. You can observe the colour change of solid particles during the reaction. Copper oxide is black colour and produced copper is red colour.
In this reaction, only one chemical is used to prepare nitrogen gas. Nitrogen gas and water vapor are given as products. Nitrogen atoms are at two different oxidation states at Ammonium nitrite. Because Ammonium nitrite can be found or easily prepared in the laboratory, this method is much convenient to use in your laboratory.
Heat orange colour Potassium dichromate ( K2Cr2O7) with ammonium chloride. Nitrogen gas, chromium oxide ( Cr2O3 ), Potassium chloride (KCl) and water are given as products. Chromium oxide is green colour. Usually both Ammonium chloride and Potassium dichromate are available in the laboratory, this method is also a easy to apply in the laboratory to prepare nitrogen gas.
As well, you can heat ammonium dichromate ((NH4)2Cr2O7) alone to prepare nitrogen gas.
When sodium azide has enough heat supply, it decomposes to sodium and nitrogen gas. This reaction is used in safety air bags in vehicles and detonator.
This is another reaction to prepare nitrogen gas. When heat is available, silver oxide decomposes to silver metal and oxygen gas because Silver oxide (Ag2O) is not stable to heat. Then produced oxygen gas will reacts with ammonia to give nitrogen gas as explained earlier in this tutorial.
Copper oxide (CuO) is stable to heat. It does not decompose to metal and oxygen gas when heat. Therefore, ammonia does not react with zinc oxide.
A redox reaction reaction occurs. Active part of bleaching powder is hypochlorite anion (OCl-). Nitrogen gas, calcium chloride and water are products.
Nitric oxide is reduced to nitrogen and ammonia is oxidized. As products nitrogen gas and water vapor are given.
6NO + 4NH3 = 5N2 + 6H2O
No. Zinc oxide does not give oxygen gas when heating (Zinc oxide does not decompose). So due to no oxygen gas, ammonia does not react and nitrogen gas is not given as a result.
Air is cooled and pressurized to liquidize. Then liquid air distillate to separate nitrogen.
Send produced gas to a magnesium metal piece and give some heat to occur the reaction (when temperature is high, it increses the reaction rate). We know alkali earth metals react with both oxygen and nitrogen gases and give metal nitrides and metal oxides.
After some time, reacted metal piece is added to the water. Both magnesium oxide and magnesium nitride will give two precipitates.
Why nitrogen gas is used in packaging goods?
Nitrogen gas is not reactive and at ordinary conditions and does not react with goods inside packages.
When both compounds are mixed, it gives ammonium cations and nitrite anions. When ammonium cations and nitrite anions are together and get heat, nitrogen gas emits.
Do not mix sodium nitrate. It will give nitrous oxide (N2O) instead of nitrogen gas.
When ammonia is heated with oxygen in thee presence of copper, nitric oxide (NO) is given. Copper is behaved as a catalyst in this reaction.
Heat + Cu (as a catalyst) + 4NH3 + 5O2 = 4NO + 6H2O
But, when ammonia gas is heated with CuO, ammonia is reduced to nitrogen gas.
2NH3 + 3CuO = N2 + 3Cu + 3H2O
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