Question

96. Magnesium is a very active metal that can be Oxidized with oxygen to MgO nitrogen to MgN2, water to Mg(OH)2 and CO2 to MgO. Write the redox reaction associated With each 0f these four oxidations. As a result of these Processes a Magnesium fire ?s particularly hazardous. Explain why water or cO2 fire extinguisher should not be used with a magnesium fire. How would you extinguish a magnesium fire?

Answer 1

Redox reactions of magnesium:

1. With oxygen
   
   2Mg(s) + O₂(g) -> 2MgO(s)
   

2. With nitrogen
   
   3Mg(s) + N₂(g) -> Mg₃N₂(s)
   

3. With water
   
   Mg(s) + 2H₂O(l) -> Mg(OH)₂(s) + H₂(g)
   

4. With CO2
   
   2Mg(s) + CO₂(g) -> 2MgO(s) + C(s)
   

Magnesium metal is highly flammable and it reacts violently with water producing hydrogen gas, which further intensifies the fire. Magnesium is such a strong reducing agent that it reacts with carbon dioxide forming carbon and magnesium oxide. Thus, Magnesium fires cannot be extinguished with water or carbon dioxide.

Magnesium does not react with sand, as it cannot reduce silicon dioxide to silicon. Thus, sand can be used to extinguish magnesium fire. Magnesium fire can also be extinguished by using class D fire extinguishing agents such as NaCl powder or copper based dry powder.