Question

Mg ribbon has a layer of MgO on it and it should be cleaned before burning but then why a white Ash is produced after burning because when magnesium reacted with oxygen earlier it just formed the white coating but now it is forming and ash so what is the reason behind it?

Answer 1

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.

When magnesium ribbon is burnt in the air, it combines with oxygen to form white powder magnesium oxide MgO with the release of heat and light. It forms a white powder of magnesium oxide. Magnesium gives up two electrons to oxygen atoms to form this powdery product.

$2Mg+O_2\to 2MgO$