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Describe with the aid of an equation how nitrogen fixation occurs in nature. - Leaving Cert Chemistry - Question A - 2005
Question A
Describe with the aid of an equation how nitrogen fixation occurs in nature.
Worked Solution & Example Answer:Describe with the aid of an equation how nitrogen fixation occurs in nature. - Leaving Cert Chemistry - Question A - 2005
Step 1
Describe nitrogen fixation
Answer
Nitrogen fixation is a process where nitrogen gas () from the atmosphere is converted into ammonia () or related compounds in soil and water. This process is essential because atmospheric nitrogen is not directly usable by most living organisms. Nitrogen fixation primarily occurs through two mechanisms: biological and abiotic processes.
Biological nitrogen fixation is carried out by certain bacteria, including free-living bacteria and symbiotic bacteria, which form relationships with plant roots. These bacteria possess the enzyme nitrogenase, which facilitates the conversion of atmospheric nitrogen into ammonia. This ammonia can then be further converted into organic forms by plants.
Abiotic nitrogen fixation occurs through processes such as lightning, where high temperatures can break apart nitrogen molecules, allowing them to react with oxygen to form nitrogen oxides.
An important equation that represents the biological nitrogen fixation is:
ightarrow 2NH_3$$Step 2
Provide the relevant equations
Answer
The following equations represent some of the nitrogen fixation processes:
- For nitrogen fixation by nitrogen-fixing bacteria:
ightarrow 2NH_3$$
- For the formation of nitrogen oxides during combustion or lightning:
ightarrow 2NO$$ or
ightarrow 2NO$$ followed by $NO + rac{1}{2}O_2 ightarrow NO_2$