Why should a magnesium ribbon be cleaned before burning in air?
Answers
Answer:
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 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+O2⟶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+O2⟶2MgO
Note: Air comprises many gases but out of them nitrogen (N2) and oxygen (O2) 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.
Answer:
Magnesium ribbon should be cleaned before burning in air due to the slow reaction of moist air on it. These hinders the burning of magnesium.So, this layer is removed by rubbing with sand paper before burning.