Question

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

Answer 1

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:

\[\ce{NaH_{(s)} + H_2O_{(aq)} -> NaOH_{(aq)} + H_{2(g)}}\]

The reaction is violent and produces fire.

 Instead of smothering the fire, the hot metal hydride will act as a reducing agent and reduce the CO₂. 

This reaction produces flammable products, including more hydrogen gas, which further fuels the fire. For example, the reaction between sodium hydride and carbon dioxide can be represented as:

\[\ce{2NaH + CO2 -> Na2CO3 + H2}\]

These fires cannot be extinguished with agents like water or CO₂ because the metals are so reactive that they can steal oxygen from the extinguishing agent, intensifying the fire.