Question

Before burning in air, the magnesium ribbon is cleaned by rubbing with a sand paper to:

Answer 1

Magnesium ribbon should be clean with sand paper before burning because when magnesium ribbon kept in air it react with the air to form the coating of magnesium oxide on its surface which prevent it form further reaction and it does not burn effectively.

Answer 2

Answer :

Magnesium is a highly reactive metal. When exposed to air for a long time it gets coated with the layer of oxide which is physically and mentally stable and therefore, partly masks the reactivity of magnesium. The oxide coating does not burn when a flame is brought in contact with the metal. Therefore, the surface should be cleaned, with a sandpaper before burning the magnesium ribbon in air.