Question

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

Answer 1

Answer:

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

Answer 2

This is because:

• Magnesium being one of the highly reactive elements reacts with oxygen in the air.
• This forms Magnesium oxide. The chemical reaction is as follows.

Mg + O₂ → MgO

• This Magnesium oxide so formed prevents or avoids the Magnesium ribbon from burning in the air which is the required experiment to be performed.

So, the Magnesium ribbon is cleaned by rubbing it with sand-paper before performing any activity.