--- title: "Dynamite, plastic explosive; nitrocellulose" subject: "Engineering Chemistry" chapter: 7 key: "semester_2/engineering_chemistry:dynamite-plastic-nitrocellulose" source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/dynamite-plastic-nitrocellulose site: BCT Engineering --- # Dynamite, plastic explosive; nitrocellulose Engineering Chemistry · Chapter 7: Explosives - Asked in: 2067 Chaitra, 2+3 marks - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/dynamite-plastic-nitrocellulose - Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-7 ## Question Define Dynamite and plastic explosive. Write the preparation, properties and uses of Nitro cellulose. ## Short answer Dynamite is nitroglycerine absorbed in kieselguhr; plastic explosive is a mouldable putty of RDX or PETN with plasticiser. Nitrocellulose is prepared by nitrating cellulose with HNO₃/H₂SO₄, yielding a white fibrous solid that burns rapidly; it is used in smokeless powder, cordite, lacquers and photographic film. ## Answer #### Dynamite Dynamite is a high explosive made by absorbing nitroglycerine (glycerol trinitrate) in an inert porous material such as kieselguhr (diatomaceous earth), usually about 75% nitroglycerine and 25% kieselguhr. It was invented by Alfred Nobel and is much safer to handle than liquid nitroglycerine. #### Plastic explosive **Plastic explosives** are high explosives (such as RDX or PETN) mixed with a plasticiser (oil, wax, polymer) to form a putty-like mass that can be moulded by hand into any shape. They are safe to handle, stable, waterproof, and need a detonator. Examples: C-4 (about 91% RDX), Semtex, PE-4. #### Nitrocellulose **Preparation:** cellulose (cotton) is nitrated with a mixture of conc. HNO₃ and conc. H₂SO₄ at about 30–40 °C for a few hours, then washed free of acid and dried. ```text [C₆H₇O₂(OH)₃]n + 3n HNO₃ --H₂SO₄--> [C₆H₇O₂(ONO₂)₃]n + 3n H₂O ``` **Properties:** white fibrous solid that looks like cotton; insoluble in water; burns rapidly and cleanly without ash; explodes when detonated or struck. The highly nitrated form (guncotton, ~13% N) is a high explosive; the less nitrated form (pyroxylin) is soluble in ether–alcohol. **Uses:** smokeless powder and cordite (with nitroglycerine), blasting gelatin, celluloid, lacquers and artificial leather, photographic film. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is dynamite? A. TNT mixed with wax B. Nitroglycerine absorbed in kieselguhr (about 75:25), safer than liquid nitroglycerine C. RDX with plasticiser D. Black powder Answer: B. Invented by Nobel; absorption makes handling safer. (Key point: Dynamite) 2. What is a plastic explosive? A. A low explosive made from plastics B. A liquid explosive absorbed in kieselguhr C. A primary explosive used in detonators D. A high explosive (RDX/PETN) mixed with a plasticiser to form a putty-like mass that can be hand-moulded Answer: D. Plastic explosives such as C-4 and Semtex are RDX/PETN with oil, wax or polymer, safe and mouldable. (Key point: Plastic explosive) 3. How is nitrocellulose prepared? A. Cellulose (cotton) is nitrated with conc. HNO3 and conc. H2SO4 at about 30-40 C, then washed and dried B. Cotton is burnt in air C. Cotton is treated with dilute NaOH D. Cotton is reacted with CH3Cl and AlCl3 Answer: A. Cellulose -OH groups are nitrated to -ONO2 using the nitrating mixture at 30-40 C. (Key point: Nitrocellulose prep) 4. Which is a use of nitrocellulose? A. Making dynamite alone B. Smokeless powder, cordite, celluloid, lacquers and photographic film C. Filling detonators D. Making soaps Answer: B. It is used in propellants and in celluloid, lacquers, artificial leather and film. 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