Ask A Scientist© Chemistry Archive

 
 >>    name         A. D. S.
 >>    status       student
 >>    age          17

 >>    Question -   WHY DOES MIXING 5 PARTS NITRIC ACID AND 4 PARTS SULFRIC
 >> ACID CAUSE A PIEce OF TISSUE TO BECOME "FLASH PAPER" OR EXTREMLY
 >> FLAMMABLE? This is the procedure. I mixed the ten mL nitric acid and 8 mL
 >> sulfric acid (slowly) then poured it into a dish.  I then put a very thin
 >> piece of toilet paper in the dish and allowed it to soak for ten min. It
 >> remained in a sheet of toilet paper but it looked gel-like and was
 >> stronger then normal tissue paper. After drying, when you burn it and
 >> drop it, it burns up before it hits the ground.  It is also called
 >> "magic" flash paper and magicians use it in their shows. I am preforming
 >> this for second graders. How so the acids, water, paper and fire interact
 >> to cause the paper to "disapear" or burn up so quickly?

You are making nitrocellulose, also known as "celluloid."  Basically,
sugars, such as the cellulose that makes up paper, are appended with
hydroxyl (OH) groups.  The nitric-sulfuric acid mixture is a nitrating
agent, converting the hydroxyl groups to nitrate esters (ONO2).  This
nitrocellulose now basically contains its own oxidizing agent.  (Basically
the same reaction occurs to make nitroglycerine from glycerol.)


                Richard E. Barrans Jr.
                CHM/200/M019
                Argonne National Laboratory
                9700 South Cass Avenue
                Argonne, IL 60439
                phone: (630) 252-6787
                fax: (630) 252-6862
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