Nitrocellulose: a fire with no burns

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.

Safe­ty pre­cau­tions

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;
• ice;
• tweez­ers;
• 100 g sodi­um bi­car­bon­ate;
• wa­ter;
• beaker;
• 2 glass bowls.

Step-by-step in­struc­tions

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.

Process de­scrip­tion

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