Magnesium ribbon is made up of pure magnesium, it is light weighted, and silvery-white in color often used in fireworks and flares. It is used in a laboratory demonstration to burn with a brilliant white flame.
So, the question is Why should a magnesium ribbon be cleaned before burning in the air? As we know, magnesium ribbon is purely made up of magnesium elements and magnesium is very reactive as it has a greater tendency to lose the electrons from its outer shell.
So, the highly reactive magnesium when kept in presence of air will react with oxygen and other impurities and get oxidized to magnesium oxide.
Now the magnesium ribbon is covered with a white layer of magnesium oxide which hindered the process of burning. Thus, the magnesium oxide layer and other impurities associated with it should be removed from the surface of the magnesium ribbon in order to burn it easily in presence of air and get the maximum result.
Oxide layers are the layers formed due to the reaction of materials surface with the oxygen. The coating of oxide layer may be functional, decorative, or protective.
What if we don’t clean the magnesium ribbon before burning it in the air?
The impurities and magnesium oxide layer will protect the surface of the magnesium ribbon to burn easily in presence of air, thus, we will not able to get the desired chemical reaction. Your laboratory experiment calculations will go wrong. The objective and the main goal of burning magnesium ribbon will be flushed down if you don’t clean it properly.
What type of protective layer forms on the surface of the magnesium ribbon?
Generally, two types of layers can be formed on the surface of the magnesium ribbon, the first is magnesium oxide(MgO), and the other is magnesium carbonate(MgCO3).
⇒ When the magnesium is kept open in the air, it instantly forms the oxide layer due to its highly reactive nature.
2Mg + O2 → 2MgO
⇒ After a while, the magnesium ribbon also comes in contact with CO2 and O2 in the presence of moisture and forms a carbonate layer.
MgO + CO2 → MgCO3
So, the two types of layer, MgO, and MgCO3 can affect the burning efficiency of magnesium ribbon if we don’t clean it properly
What material should be used to clean the magnesium ribbon?
The steel wool or sandpaper can be used to remove the protective layer on the surface of magnesium ribbon in form of oxide or carbonate caused due to the reaction of magnesium with atmospheric oxygen.
⇒ “The steel wool is a bundle of very fine and flexible sharp-edged steel filaments uses a cleaning, sanding surfaces, and as an abrasive in finishing”.
⇒ The sandpaper as the name suggests is a paper covered with sand as abrasive material on one side and used to remove the impurities on surfaces efficiently and quickly.
How can you differentiate between corroded and cleaned magnesium ribbons?
A corroded magnesium ribbon looks dirty covered with a white-blackish layer of MgO and MgCO3, also, other types of impurities produced from reacting with atmospheric air are present on the surface of it.
A non-corroded magnesium ribbon looks clean, light, and silvery-white in color. There are not any types of impurities present on the surface of it. It is just made up of pure magnesium elements.
Is the burning of magnesium ribbon, exothermic or endothermic?
The burning of magnesium ribbon is exothermic in nature as when magnesium is oxidized then energy is released in form of light and heat to stable the bond formed between magnesium and oxygen.
The bond formed between magnesium and oxygen is ionic in nature and the energy released during the reaction is called lattice energy.
Is the burning of magnesium ribbon, a physical or chemical change?
A physical change is a change that occurs in a substance without affecting its molecular structure or internal composition. No new substance formed in physical changes and it is easily reversible.
A chemical change forms a new substance by affecting the chemical composition and in most cases, they are not reversible.
So, when we burn the magnesium ribbon in presence of air then magnesium gets oxidized to magnesium oxide due to its high reactivity nature.
This magnesium oxide cannot be reverted back to its original state, so, it is irreversible, also, magnesium oxide is a new substance that formed because of a chemical reaction that occurs between air and magnesium.
2 Mg (s) + O2 (g) → 2 MgO (s)
Hence, the burning of the magnesium ribbon is a chemical change.
Note: Burning of anything is a chemical change in nature as they are mostly irreversible once changed into a new substance.
What actually happens when you burn the magnesium ribbon in the air?
First, you should clean the magnesium ribbon before burning it in the air to get the desired result.
After this, when magnesium ribbon is heated in the presence of air then magnesium reacts with oxygen and produces dense white fumes giving off a brilliant white light that can make you blind temporarily because of the occurrence of an intense exothermic reaction in this process.
After that, these fumes form a magnesium oxide as a white powder.
It should be noted that the burning of magnesium ribbon produces magnesium oxide as well as magnesium nitride (Mg3N2) as magnesium can react with oxygen and nitrogen in the air.
⇒ 3Mg+N2 → Mg3N2
How do chemical reactions occur when magnesium ribbons are burnt in the air?
When magnesium ribbon is burnt in the air then magnesium metal will lose its two-electron to get the stability and oxygen nonmetal will take those two electrons to complete the octet and obtain stability.
This will form the two ions, Mg2+ and O2-, then these ions will be attracted by the electrostatic force of attraction and joined together with an ionic bond.
In this process, a lot of heat and light is released, and the formation of magnesium oxide(white powder) occurs.
Key Takeaways: Why should a magnesium ribbon be cleaned before burning in the air?
- The formation of magnesium carbonate and magnesium oxide coating slows down or even prevents the chemical reaction when magnesium ribbon burns in the air, hence, it should be clean to make the reaction faster and get the desired result.
- The burning of magnesium ribbon is an exothermic process as it liberates a large amount of energy in form of heat and light when burns down in the air.
- When magnesium ribbon is burnt then we observe a white powder (magnesium oxide) and a very bright white flame.
- The steel wool or sandpaper should be used to clean the magnesium ribbon before burning it in the presence of air.