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Why does magnesium produce a bright light when reacted with fire?
Question Date: 2010-01-11
Answer 1:

Well its not so much that the Mg strip is "burned" with fire. The reason why the Mg emits light is because it gets very hot. The reason why it gets hot is that there is a COMBUSTION reaction such the Mg metal plus oxygen makes MgO called magnesium oxide. When this reaction occurs, energy is given off and that heats the Mg metal. But the RATE of the reaction depends on Temp! So as it heats up the reaction goes faster...and as it reacts faster more heat is given off and that...makes the reaction go even faster!!!

So its basically the same as burning a lump of carbon... C plus oxygen gives CO2... in the case with Mg, the Mg makes a new solid material called MgO of the mineral periclase. When you burn Mg you will notice a residue... thats the Mg oxide.

Answer 2:

Thank you for your question! Magnesium is in Group 2 of the periodic table. This means that magnesium has 2 electrons in its outer shell making it highly reactive to oxygen. When putting magnesium metal in fire you are supplying enough energy so that magnesium can start reacting with oxygen in the air to form magnesium oxide. The reaction of magnesium with oxygen releases a huge amount of energy which you can see as heat and bright light.

Answer 3:

When magnesium burns, it is actually reacting with oxygen in the air and not with fire. Fire is what we call the heat and light produced when things burn.

Magnesium reacts with oxygen to make a compound called magnesium oxide.

2Mg + O2 ---> 2MgO

The bright light results because this reaction produces a lot of heat. When the magnesium gets really hot, it emits energy in the form of light (heat is also how the sun produces light). Since it emits all visible wavelengths at a relatively equal rate, the light looks white-ish. Be careful when burning magnesium though, because it also produces ultra-violet (UV) light which can damage your eyes if you stare at it for too long.

The process of hot objects emitting light is known as incandescence (like an incandescent light bulb). The spectrum of light emitted by hot objects is known as black body radiation. If you want to know a little more about these topics, you can look at this website:


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