Question

Why mgnesium ribbon be cleaned before burning in air ?????

Answer 1

When magnesium ribbon is kept in air it quickly reacts with oxygen and forms magnesium oxide this layer prevents the magnesium to be over reactive when the ribbon is cleared it helps magnesium to burn faster .
it is cleaned to remove magnesium oxide

Answer 2

♤ When Magnesium ribbon is exposed in the atmosphere it form a layer of magnesium oxide on its surface.

♤ This layer of magnesium oxide is stable compound to prevent further reaction of magnesium with oxygen.

♤ Hence, it should be cleaned before burning in air to remove this layer so that the metal can be exposed to air properly.