Question

Magnesium powder burns in air to give:
A. $MgO$ only
B. $MgO$ and $Mg{{(N{{O}_{3}})}_{2}}$
C. $MgO$ and $M{{g}_{3}}{{N}_{2}}$
D. $Mg{{(N{{O}_{3}})}_{2}}$ and $M{{g}_{3}}{{N}_{2}}$

Answer 1

You should know that the two major component gases in the air are nitrogen and oxygen. Therefore, the burning of magnesium in the air should result in the production of compounds obtained when it will react with these two gases. So, find out the products, when magnesium will react with these two gases.

Complete step by step solution:
Given that, Magnesium powder burns in the air and we have to find out which products are formed. So, having seen the hint, magnesium reacts with two gases (oxygen and nitrogen) that are present in the air. Let us look at the reaction between magnesium and oxygen. This reaction may be referred to as a combustion reaction, as it will give heat and light and the balanced chemical reaction is as follows:
$2M{{g}_{(s)}}+{{O}_{2(g)}}\xrightarrow{\Delta }2Mg{{O}_{(s)}}$
So, we can see that the product formed in this reaction is magnesium oxide whose chemical formula is $MgO$. Now, let us see what product is formed by the reaction between magnesium and nitrogen:
$3M{{g}_{(s)}}+{{N}_{2(g)}}\xrightarrow{\Delta }M{{g}_{3}}{{N}_{2(s)}}$. So, we can see that the product formed by the reaction between magnesium and nitrogen is magnesium nitride, whose chemical formula is $M{{g}_{3}}{{N}_{2}}$. Therefore, the products formed when magnesium powder is burnt in air are $MgO$ and $M{{g}_{3}}{{N}_{2}}$.

Hence, the correct option is C.

Note: Magnesium is a metal and is placed in the second group of the Periodic table. It reacts violently with water, so the reaction of magnesium with water is avoidable. Magnesium burning in the air is a type of exothermic reaction as it gives heat and light.