magnesium metal burns in air producing intense light magnesium burning
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Magnesium metal burns in air producing intenselight
Magnesium Burning
Demonstration The reaction was initiated in a
flame
The reaction produced intense light
The magnesium reacted with the oxygen and nitrogen in the atmosphere to form solid products
Purpose To observe a metal while it burns
Concepts
1. Combustion Reactions
2. Combination Reactions
3. Energy
1. Combustion Reactions “Burning” reactions Usually organic substances
wood paper
By definition a combustion reaction is the exothermic reaction of a substance, usually with oxygen (but not always)
Light typically is also a product of the reaction
Metals also burn!
2. Combination Reactions General form
A + B C
In this demonstration 2 Mg + O2 MgO
3 Mg + N2 Mg3N2
The oxygen and nitrogen occur
naturally in the atmosphere O2 is 21% of air N2 is 78% of air
3. Energy Two types of energy are produced in this
demonstration heat energy Hf MgO = -601.83
kJ/mole (kiloJoules per mole) this is said to be the ‘heat of
formation’ for MgO the negative sign indicates the
formation is exothermic
light energy approximately 10% of the energy of
combustion occurs as light in this demonstration
more light than any other known reaction
Conclusions When the energy of activation was
applied magnesium burst into flame
Magnesium burned with the intense production of light and heat
The reaction was a combination reaction which used gaseous components from the atmosphere
Comments This is a redox reaction in addition to a
combination and combustion reaction
Mg begins as oxidation number 0 In both magnesium oxide and
magnesium nitride the oxidation number of magnesium is 2+
magnesium has lost electrons therefore has been oxidized
Flashbulbs contain magnesium filaments
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