2. Combustion of Nitrocellulose A modified form of cotton burns quickly leaving little residue

3. Purpose  To observe a rapid combustion reaction  To compare the combustion of untreated cotton with treated cotton

4. Demonstration  The combustion reaction was extremely rapid, leaving little residue

5. Concepts 1.Polymers 2.Polymer Modification 3.Nitration 4.Flash Point

6. 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

7. 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 -etc-Glu

8. 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 N O O

9. 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

10. Conclusions  Cotton had been treated in order to nitrate it  The modified cotton burned extremely fast

11. Comments  Guncotton has applications in explosives and propellants  Guncotton is soluble in alcohol and ether and may be used to cast films and coatings