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

Magnesium is chemically very active, it takes the place of hydrogen in boiling water and a great number of metals can be produced by thermic reduction of its salts and oxidized forms with magnesium. Magnesium is labelled as the eighth most abundant element and about 2% of earth’s crust is constituted by Magnesium.

In seawater, it is the most plentiful element present. It is not only found in seawater but also in underground brines and salty layers. After aluminium and iron, magnesium is the third most abundant structural metal in the earth’s crust.

Magnesium ribbon should be cleaned with sandpaper before burning in the air

It should be cleaned before burning due to the following reasons:

• Magnesium very reactive element which rapidly reacts with oxygen in the air to form a white layer of magnesium oxide and this layer will not burn.
• To remove the Magnesium oxide layer from the ribbon which may prevent or slow down the burning of magnesium ribbon.
• Unwanted impurities deposited on the magnesium ribbon can be removed and only pure magnesium can be used for the reaction.