Question

why should a magnesium ribbon be cleaned before burning in air?

Answer 1

because the magnesium oxide which is formed due to expose d to air needs to be cleaned before reacting it with oxygen otherwise reaction will not occur

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.