Hint: Magnesium is an extremely reactive metal. When exposed to open air, it can react with the gases in the atmosphere. Cleaning will eliminate the impurities created from this reaction with air.
Complete Answer:
Let’s explore the significance of cleaning the surface of magnesium ribbon prior to burning it.
- Magnesium belongs to the alkaline earth metals group. Elements in the second column of the periodic table are categorized as alkaline earth metals. They are highly reactive because they possess only two electrons in their outermost electron shell.
- This high level of reactivity is why magnesium ribbons need to be cleaned before use.
- When a magnesium ribbon is left exposed to air for an extended period, it reacts with the oxygen in the atmosphere, resulting in the oxidation of the magnesium ribbon into magnesium oxide.
2Mg+ O2⟶2MgOO2⟶2MgO
The oxide layer on the magnesium ribbon forms on its surface and gives it a white appearance. This coating prevents the ribbon from burning easily, as it does not ignite readily.
Therefore, since the oxide layer obstructs the burning of the ribbon, it needs to be removed. To achieve this, we must clean the surface of the ribbon. Cleaning the magnesium ribbon removes the oxide layer, enabling the ribbon to burn efficiently and achieve the intended result.
The magnesium ribbon ignites in air, generating intense heat and emitting a bright white light. Oxygen in the air reacts with magnesium to create magnesium oxide. The chemical reaction for this process is the same as stated above: 2Mg+O2⟶2MgO2Mg+O2⟶2MgO .
Note: Air consists of various gases, with nitrogen (N₂) and oxygen (O₂) being the primary components. It is important to remember that magnesium reacts exclusively with the oxygen in the air to form an oxide layer on its surface, while it does not react with atmospheric nitrogen. This is due to the fact that gaseous nitrogen is quite inert and does not interact with magnesium.