Question

Why should magnesium ribbon be cleaned before burning in air?

Answer 1

when magnesium ribbon remains exposed to moist air a white layer of MgO is formed on it's surface.This hinders the burning of magnesium.hence this layer is first removed with sandpaper before burning.

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.