Why Should A Magnesium Ribbon Be Cleaned Before Burning In Air?

It is important to clean the magnesium ribbon because the surface layer formed due to oxidation can hinder the burning process

A magnesium ribbon is a thin strip of elemental magnesium, which has various uses. It can be used in laboratories for various experiments or for starting thermite reactions. Magnesium ribbons can also be used to demonstrate the working of sacrificial anodes, which are used in water heaters and ships to protect core components from rust. However, there are some guidelines about the right way to use a magnesium ribbon. Let us take a look at why should a magnesium ribbon be cleaned before burning in air.

Why clean a magnesium ribbon before using it?

To understand why a magnesium ribbon should be cleaned, we first need to understand how magnesium reacts with air. While people with knowledge of science may already know how it works, it is worth mentioning that pure magnesium is highly reactive. When exposed to air, the magnesium ribbon forms a thin protective oxide layer on the surface. The chemical reaction is 2Mg(s) + O₂(g) → 2MgO(s).

This oxide layer protects the metal by limiting the contact with the oxygen in the air. However, this may reduce the effectiveness of a magnesium ribbon for the intended purposes. Given below are some outcomes that can occur if the magnesium ribbon is not cleaned before using it.

• When an oxide layer forms on the surface of the magnesium ribbon, it can hinder the burning process
• It may become difficult to ignite the magnesium ribbon
• The magnesium ribbon is likely to burn dimly or incompletely
• The intended rapid reaction and the characteristic dazzling white flame may be difficult to produce
• In addition to the oxide layer, other unwanted stuff such as dust can also interfere with the intended experiment objectives

How to clean a magnesium ribbon?

It is quite easy to clean a magnesium ribbon. You can simply use sandpaper to gently clean the surface. An emery paper or a file can also be used to clean a magnesium ribbon. It is important to understand that the oxide layer on a magnesium ribbon is actually quite thin. If you have just purchased the magnesium ribbon, the oxide layer can be around a few nanometers (nm).

However, if the magnesium ribbon is stored for several months, it can develop a protective layer of thousands of nanometers. It is recommended that you start with gentle scrubbing until a fresh, shiny surface is achieved. This will ensure the best outcomes with your experiments. Once cleaned, the magnesium ribbon will burn vigorously in air with a dazzling white flame. Magnesium also reacts with nitrogen in the air, forming magnesium nitride (Mg₃N₂). However, the main product is the oxide.

While experiments with a magnesium ribbon can be fun, please note that the element burns quite vigorously. The burning produces intense light including ultraviolet light (UV), which can be damaging to the eyes. It is important to not look directly at the burning magnesium ribbon. Make sure you perform the experiments using proper safety gear and in a well-ventilated area.