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Answer: Magnesium is a reactive metal, but its reaction with water depends on the temperature and form of magnesium. Magnesium reacts very slowly with cold water but reacts more vigorously with hot water or steam.
Complete Answer:
Reaction of Magnesium with Cold Water
When magnesium is added to cold water, the reaction is very slow because a thin layer of magnesium hydroxide (Mg(OH)₂) forms on its surface. This layer prevents further reaction.
The reaction equation is:
- Magnesium hydroxide is slightly soluble in water and forms a weak alkaline solution.
- Hydrogen gas is released in very small amounts.
Reaction of Magnesium with Hot Water
When magnesium is added to hot water, the reaction speeds up. The thin Mg(OH)₂ layer dissolves more quickly, allowing continuous reaction. The reaction still produces magnesium hydroxide and hydrogen gas but at a faster rate.
Reaction of Magnesium with Steam
When magnesium reacts with steam (water in gaseous form), the reaction is much faster and more vigorous compared to cold or hot water. The reaction forms magnesium oxide (MgO) and hydrogen gas.
- Magnesium oxide is a white powder that does not form an alkaline solution like Mg(OH)₂.
- The reaction is exothermic, meaning it releases heat.
Observations of the Reaction
Cold water: Very slow reaction, few bubbles of hydrogen gas.
Hot water: Faster reaction with more hydrogen gas release.
Steam: Vigorous reaction with bright white light and rapid hydrogen gas release.
Fun Fact About Magnesium
Magnesium burns with an intense white flame. Because of this, it is used in fireworks, flares, and photography flashbulbs!
Applications of Magnesium in Water Reactions
- Magnesium hydroxide (from reaction with cold water) is used as an antacid in medicine to neutralise stomach acid.
- Magnesium oxide (from reaction with steam) is used in ceramics and fireproof materials.
Common Doubts in Chemistry
