100 likes | 494 Views
Oxidation of Phosphorus. Phosphorus spontaneously combines with oxygen in the atmosphere. Demonstration. The lump of phosphorus burned with no outside initiation, demonstrating a combustion reaction The film of phosphorus did not burn but glowed, demonstrating photoemission. Purpose.
E N D
Oxidation of Phosphorus Phosphorus spontaneously combines with oxygen in the atmosphere
Demonstration • The lump of phosphorus burned with no outside initiation, demonstrating a combustion reaction • The film of phosphorus did not burn but glowed, demonstrating photoemission
Purpose • To observe a combination reaction involving phosphorus and atmospheric oxygen • To compare the behavior of a lump of phosphorus to a thin film of phosphorus
Concepts 1. Combination Reactions 2. Reaction Kinetics 3. Photoemission
1. Combination Reactions • In both demonstrations phosphorus combines with oxygen from the atmosphere • Combination reactions have the general form A + B C • The chemical equation is P4 + 5O2 P4O10 • the reaction is exothermic • the name of the product is tetraphosphorous pentoxide
2. Reaction Kinetics • Since both demonstrations involve the same chemical reaction they both are exothermic • Since in the lump the phosphorus is not dispersed the heat of reaction is intense enough to speed the reaction and to cause the lump to burst into flame • When the phosphorus is spread thinly the heat dissipates and photoemission is able to be observed
3. Photoemission • The emission of light by a substance • In this demonstration it is a greenish glow • Caused by a substance in the excited state having high energy electrons giving off visible energy when the electrons return to the ground state
Conclusions • The concentration of a compound influenced the rate at which it reacted • Different effects were observed depending on the concentration • combustion or • photoemission
Comments • The phosphorus was dissolved in a solvent then dispersed in mineral oil before spreading • The intermediate species responsible for photoemission is PO which is ultimately converted to P4O10