Page 183 - ICSE Chemistry 8

Reactivity with Metals

Metals react diff erently with water based on their posi on in the metal ac vity (reac vity) series.

Reaction of Metals with Cold Water

Metals posi oned above magnesium in the reac vity series react vigorously with cold water and o en
catch fi re. Metals such as potassium (K), calcium (Ca) and sodium (Na) react with cold water to form metal
hydroxides and hydrogen gas.

2Na + 2H O 2NaOH + H 
2
2
Sodium Water Sodium hydroxide Hydrogen gas

2K + 2H O 2KOH + H 
2
2
Potassium Water Potassium Hydrogen
hydroxide gas
Ca + 2H O Ca(OH) 2 + H 
2
2
Calcium Water Calcium hydroxide Hydrogen gas
Metals like Mg, Al, Zn, Fe, Ni, Sn, Pb, Cu, Hg, Ag and Au do not react with cold water.

Reaction of Metals with Hot Water

Magnesium reacts slowly with hot water to form white sparsely soluble magnesium oxide and hydrogen
gas.
Mg + 2H O Mg(OH) 2 + H 
2
2
Magnesium Water Magnesium hydroxide Hydrogen gas
Reaction of Metals with Steam

Magnesium reacts with steam vigorously and forms a white solid of magnesium oxide and hydrogen gas.
An intense white light is seen when the reac on occurs. Zinc and iron also react similarly with steam but
the reac on is less vigorous.

Zn + H O ZnO + H 
2
2
Zinc Water Zinc oxide Hydrogen gas
3Fe + 4H O Fe O 4 + 4H 
3
2
2
Iron Water Iron oxide Hydrogen gas
Aluminium also reacts with steam readily to give aluminium oxide and hydrogen gas. This reac on
however stops a er a short while. This happens because a thin but strong layer of aluminium oxide covers
the metal and does not allow the reac on to proceed further.

2Al + 3H O Al O 3 + 3H 
2
2
2
Aluminium Water Aluminium oxide Hydrogen gas
Metals like Pb, Cu, Hg, Ni, Ag and Au do not react with water in any form.

169