Engineering Chemistry S Datta

348 ENGINEERING CHEMISTRY
Highlights:
Explosive: Explosives are pure substances or mixture, which when subjected to
specific stimulus initiate an oxidation reaction producing large volume of hot gases.
Primary explosives: They are highly sensitive explosives, which explode on
receiving a slight shock or fire.
High explosives: High explosives have higher energy content compared to primary
explosives but they are quite insensitive to external stimuli.
Propellants: Propellants are pure substances or mixtures in liquid or solid state
that burn exothermally without contact with atmospheric oxygen and form large
volume of gaseous products.
Fuses: Fuse is a thin water-proof canvas length of tube which contains gun-powder
that burn at a given speed for setting off charges of explosives.
Dynamites: Explosives containing nitroglycerine as the principal ingredient.
RDX: Powerful explosive consisting of cyclotrimethylene trinitroamine.
SHORT QUESTIONS AND ANSWERS
Q. 1. What are explosives?
Ans. Explosives are substances or mixtures, which when subjected to mechanical or
thermal shock, lead to rapid oxidation exothermally to produce large amount of gaseous products
of greatly increased volume and also a large amount of energy.
Q. 2. What is a rocket propellant?
Ans. Rocket propellant is either a high oxygen containing fuel or a fuel with an oxidant
which is burnt under controlled condition with the evolution of a large volume of gas.
Q. 3. What are dynamites?
Ans. Dynamites are high explosives containing nitroglycerine as the principal ingredient.
Nitroglycerine is usually mixed with an inert absorbent like wood pulp, starch meals, saw dust
etc. with varying amount of nitroglycerine that determines its relative strength.
Q. 4. What are fuses?
Ans. Fuses are thin water-proof canvas length of tube containing gun-powder or TNT,
which burn at a given speed for setting-off the charges of explosive. Fuses are of two types:
(i) safety fuse, (ii) detonating fuse.
Q. 5. What do you mean by “oxygen-balance of an explosive”?
Ans. Positive oxygen balance is an important characteristic of a good explosive. It
indicates the oxygen contained in the molecule, which will be utilized to oxidize the C and H of
the molecule to form CO 2
and H 2
O, respectively. It is expressed as the difference between the
oxygen contained in the molecule and the oxygen actually required to oxidise the total C and H
contained in the molecule.
EXERCISES
1. What are explosives? What are rocket propellants?
2. How are explosives classified?