Question

X is a silvery white metal. X reacts with oxygen to form Y. The same compound Y is obtained from the metal X on reaction with steam with the liberation of hydrogen gas. Identify X and Y.

Answer 1

Hint:The element X is a typical metal. It is a group 13 element of the modern periodic table. The metal X is also used in making cooking utensils and appliances.

Complete step by step solution:
The element is a very well known element, that is, aluminium. When aluminium reacts to oxygen it forms its oxide that is aluminium oxide. The reaction occurs as follow:
\[4{\text{Al}} + 3{{\text{O}}_2} \to 2{\text{A}}{{\text{l}}_2}{{\text{O}}_3}\]
The aluminium has an atomic number 13 and has 3 electrons in its valence shell and so the valency of aluminium is 3. The oxygen is a group 16 element and has 6 electrons in its valence shell and the valency of oxygen is 2. Hence, they cross exchange the valency and the formula of the oxide formed will be \[{\text{A}}{{\text{l}}_2}{{\text{O}}_3}\] .
Now the reaction of aluminium with the stream that is water vapours occurs as follow:
\[{\text{2Al}} + 3{{\text{H}}_2}{\text{O}} \to {\text{A}}{{\text{l}}_2}{{\text{O}}_3} + 3{{\text{H}}_2}\]
Most of the metals follow the above reaction, that is, they react with water to liberate hydrogen gas. Some metals are more reactive towards the water such as sodium which even reacts with normal water or even with cold water. Aluminium is less reactive that is why it reacts with steam to form aluminium oxide.

The metal X is Aluminium metal. The compound Y is Aluminium oxide which is commonly called alumina.

Note:
Both the above reactions are the oxidation reaction of aluminium. The former one is a direct oxidation reaction of aluminium with oxygen whereas the later one is a redox reaction where aluminium is getting oxidised by gaining oxygen and water is getting reduced by losing oxygen.