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Saline hydrides are known to react with water violently producing fire. Can CO2, a well known fire extinguisher, be used in this case? Explain. 

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Saline hydrides (i.e., NaH, LiH, etc.) react with water to form a base and hydrogen gas. 

The chemical equation used to represent the reaction can be written as: 

The reaction is violent and produces fire. CO2 is heavier than dioxygen. It is used as a fire extinguisher because it covers the fire as a blanket and inhibits the supply of dioxygen, thereby dousing the fire. CO2 can be used in the present case as well. It is heavier than dihydrogen and will be effective in isolating the burning surface from dihydrogen and dioxygen. 

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Saline hydrides react with water violently to form the corresponding metal hydroxide, thereby liberating dihydrogen gas, e.g.,

These reactions are highly exothermic and H2. H2 thus evolved catches fire. The fire, thus produced cannot be extinguished by CO2. CO2, as it gets reduced by the hot metal hydride to form metal formate. To extinguish such type of fire, SAND  can be used, since it is a highly stable solid.
NaH+CO2→HCOONa (sodium formate)

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