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Combustion of Nitrocellulose. A modified form of cotton burns quickly leaving little residue. Purpose. To observe a rapid combustion reaction To compare the combustion of untreated cotton with treated cotton. Demonstration.
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Combustion of Nitrocellulose A modified form of cotton burns quickly leaving little residue
Purpose • To observe a rapid combustion reaction • To compare the combustion of untreated cotton with treated cotton
Demonstration • The combustion reaction was extremely rapid, leaving little residue
Concepts 1. Polymers 2. Polymer Modification 3. Nitration 4. Flash Point
1. Polymers • Polymers are huge molecules • molecular weights in 10,000X • composed of monomer units • many are found naturally • cotton • wool • DNA • many are synthetically produced • plastics • nylon • In this demonstration the polymer used is cotton
2. Polymer Modification • Cotton is a polymer made of hundreds of glucose units attached sequentially to each other • For this demonstration cotton was nitrated using a mixture of sulfuric and nitric acid to give the nitrocellulose Glu -Glu -Glu -Glu -Glu -Glu -Glu -Glu -Glu -etc
O N O 3. Nitration Reactions • Nitration is a common reaction for organic (carbon) compounds • A nitro group is added to a molecule simply by treating it with sulfuric and nitric acid molecule • In this demonstration cotton was nitrated to give nitrocellulose
4. Flash Point • Flash Point is the temperature to which a compound must be heated before it will ignite by a flame in the presence of air • flash point of gasoline is -45 degrees Celsius • flash point of motor oil is 232 degrees Celsius • flash point of nitrocellulose is 4 degrees Celsius
Conclusions • Cotton had been treated in order to nitrate it • The modified cotton burned extremely fast
Comments • Guncotton has applications in explosives and propellants • Guncotton is soluble in alcohol and ether and may be used to cast films and coatings