Question

Why do metal combined with oxygen to form metal oxide ? Explain this in brief
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Answer 1

Answer:

Metals react with oxygen to form metal oxides.These metal oxides are basic in nature.

Metal + Oxygen ————>Metal Oxide

1)When magnesium burns in air,it combines with the oxygen of air to form magnesium oxide(basic oxide)

Magnesium +oxygen ——–> Magnesium Oxide

2 Mg(s) + O2 (g) —–> 2MgO(s)

Magnesium oxide dissolves in water to form magnesium hydroxide solution.

MgO + H20 —–> Mg(OH)2

Magnesium hydroxide turns red litmus to blue which shows that magnesium oxide is a basic oxide.

2)When sodium burns in air,it combines with the oxygen of air to form sodium oxide(basic oxide)

Sodium +oxygen ——–> Sodium Oxide

4Na(s) + O2 (g) —>2 Na2O (s)

Sodium oxide dissolves in water to form Sodium hydroxide solution.

Na2O (s) + H20 (l) —> 2NaOH (aq)

3)During the rusting of iron,iron metal combines slowly with the oxygen of air in the presence of water to form a compound called iron oxide.This iron oxide is rust.

3Fe(s) + O2 (g)+ H20 (l) —–> Fe2O3 (s)

4)When a copper object is exposed to moist air for a long time,then copper react with water,carbon dioxide and oxygen present in moist air to form a green coating on the copper object.

The green coating is a mixture of copper hydroxide and copper carbonate which is formed by the action of moist air on copper objects.

The mixture of copper hydroxide and copper carbonate which forms the green coating is known as basic copper carbonate.

The formation of green coating of basic copper carbonate on the surface of copper objects on exposure to moist air is called corrosion of copper.

Non-metals react with oxygen to form non-metal oxides.Non-metal oxides are acidic in nature.They turn blue litmus to red.

1)When sulphur burns in air,it combines with the oxygen of air to form sulphur dioxide (acidic oxide)

S (s) + O2 (g) ——> SO2 (g)

Sulphur dioxide dissolves in water to form sulphurous acid solution

SO2 (g) + H20 (l) —–> H2SO3 (aq)

Sulphurous acid turns blue litmus to red showing it is an acid and that sulphur dioxide is acidic in nature.

If an element forms a basic oxide,then the element will be a metal.