Nitrocellulose: a fire with no burns
How to make cotton wool burn in a few seconds
What do you think – can a substance burn without burning you? Have a look at an experiment with nitrocellulose – a substance that burns up so quickly that the flame doesn’t have time to damage the skin.
Wear protective gloves, eyewear, and a mask. Work in a well-ventilated room. Observe safety precautions when working with concentrated acids, fire, and flammable substances.
Reagents and equipment
- 5 g cotton wool;
- 10 mL concentrated nitric acid;
- 20 mL concentrated sulfuric acid;
- 100 g sodium bicarbonate;
- 2 glass bowls.
The first glass bowl is filled with ice, and the beaker with cotton is placed on the ice. The cotton is soaked in a nitrating mixture consisting of sulfuric and nitric acid in a 2:1 ratio. The contraption is left for 30 minutes. The resulting nitrocellulose is immersed in a bowl of water and 100 g sodium bicarbonate to neutralize any remaining acid. The nitrocellulose is left to dry for approximately three hours, then lit. The nitrocellulose burns noticeably faster than ordinary cotton wool.
Cotton consists mainly of cellulose – a natural polymer that can be used to obtain the curious substance known as nitrocellulose. Nitrocellulose is a complex ether of cellulose and nitric acid. It is used to manufacture ping pong balls, and as a fast-burning component in explosive mixtures, smokeless gunpowder, and a magician’s bag of tricks. In the past, it was also used as a mount for camera and cinema film, but was later replaced with safer materials due to its flammability. Even though nitrocellulose burns too rapidly to harm skin, non-professionals should not attempt this experiment.
(C₆H₁₀O₅)ₙ + nHNO₃+H₂SO₄ = [C₆H₇(NO₂)₃O₅]ₙ + H₂SO₄ + nH₂O