VerifiedHint: Magnesium is a very reactive metal. When it is kept in the open air it can react with the gases present in the air. Cleaning will remove those impurities formed due to the reaction with air.
Complete Answer:
Let us see why it is important to clean the surface of the magnesium ribbon before burning it.
- Magnesium is an alkaline earth metal. Metals which are in the second group of the periodic table are called the alkaline earth metals. They are very reactive since they have just two electrons in their outer electron shell.
- This high reactive nature of magnesium is the reason why magnesium ribbons should be cleaned before using it.
- When we keep a magnesium ribbon in contact with air for a long time, it reacts with the oxygen present in the air and the magnesium ribbon gets oxidised into magnesium oxide.
2Mg+ $ { O }_{ 2 }\longrightarrow 2MgO $
- The oxide coating on the magnesium ribbon is formed on the surface of the ribbon and it turns the ribbon white. This coating hinders the burning of the ribbon as this layer does not burn easily.
- So, we know since the oxide layer hinders the burning of the remove we have to remove it. To do so we have to clean the surface of the ribbon. Cleaning the surface of the magnesium ribbon will remove the oxide layer from the surface and thus it will allow the ribbon to burn effectively to get the desired result.
The magnesium ribbon burns in air producing intense heat and producing bright white light. The oxygen from the air reacts with magnesium to form the magnesium oxide. The reaction for this is the same reaction given above: $ 2Mg + { O }_{ 2 }\longrightarrow 2MgO $ .
Note: Air comprises many gases but out of them nitrogen $ ({ N }_{ 2 } ) $ and oxygen $ ( { O }_{ 2 } ) $ are its major components. Always remember that magnesium only reacts with oxygen in the air to form an oxide coating on its surface but it does not react with the atmospheric nitrogen at all. This is because gaseous nitrogen is very inert and it does not react with magnesium.
