Question

How will the following metals react with water, (i) sodium, (ii) magnesium and (iii) iron? Give reasons.​

Answer 1

Answer:

i) Na + H2O ----> NaOH + H2+ Heat

Na reacts with cold water

ii) Mg + H2O ----> Mg(OH)2 + H2

Mg reacts with hot water

iii) Fe + H2O ----> Fe3O4 + H2

Fe reacts with steam

Answer 2

Answer:

i) Sodium is a highly reactive metal so it reacts with cold water vigorously. The reaction is highly exothermic and hydrogen gas evolved catches fire because of the heat evolved.

Na + H2O----->NaOH + H2 + heat energy

ii) Magnesium doesnt react with cold water and reacts with hot water to form Magnesium hydroxide and Hydrogen gas. The effervescent (bubbles) of hydrogen gas sticks to its surface which makes it float.

Mg + 2H2O------> Mg(OH)2 + H2

iii) Iron doesnt react with hot or cold water. It reacts with steam.

3Fe + 4H2O-----> Fe3O4 + 4H2