NVRSCHEM17

EXPLOSIVES : 

EXPLOSIVES

EXPLOSIVES : 

EXPLOSIVES DEFINITION CHARACTERISTICS OF EXPLOSIVE CLASSIFICATION OF EXPLOSIVES APPLICATION OF EXPLOSIVES GLOSSARY REFERENCES

DEFINITION: An explosive is a substance or a mixture, which under the influence of thermal or mechanical shock, decomposes rapidly and spontaneously with the evolution of a great amount of heat and large volume of gases. : 

DEFINITION: An explosive is a substance or a mixture, which under the influence of thermal or mechanical shock, decomposes rapidly and spontaneously with the evolution of a great amount of heat and large volume of gases.

CHARACTERISTICS OF ANEXPLOSIVE : 

Explosives must contain at least one weak chemical bond that can be easily broken. It should be cheap and stable under normal conditions. Its rate of decomposition should be fast to produce a large volume of gaseous products. It should possess high shattering power. It should have a positive oxygen balance. CHARACTERISTICS OF ANEXPLOSIVE

OXYGEN BALANCE : 

OXYGEN BALANCE The oxygen balance is a measure of the oxygen contained in the molecule which is used to oxidize the C to CO2 and H to H2O respectively. Normally, it is expressed as a percentage surplus or deficiency of oxygen by weight.

Consider this reaction CxHyOz ?xCO2 + y/2H2O + z-(x+y/2) O2 where z = No. of Oxygen atoms x = No. of Carbon atoms & y = No. of Hydrogen atom : 

Consider this reaction CxHyOz ?xCO2 + y/2H2O + z-(x+y/2) O2 where z = No. of Oxygen atoms x = No. of Carbon atoms & y = No. of Hydrogen atom

Example 1.Oxygen balance of NH4NO3 (Mol Wt=80) can be calculated as:-z-(x+y/2)=3-(0+4/2)=3-0-4/2=1Oxygen balance=1x16x100 =20 80 : 

Example 1.Oxygen balance of NH4NO3 (Mol Wt=80) can be calculated as:-z-(x+y/2)=3-(0+4/2)=3-0-4/2=1Oxygen balance=1x16x100 =20 80

2.Similarly,oxygen balance of C6H3(NO2)3(Trinitrobenzene) whose molecular weight is 213,can be calculated as z-(x+y/2)=6-6-3/2=-1.5Oxy. bal.= -1.5x16x100 = -11.3 213 : 

2.Similarly,oxygen balance of C6H3(NO2)3(Trinitrobenzene) whose molecular weight is 213,can be calculated as z-(x+y/2)=6-6-3/2=-1.5Oxy. bal.= -1.5x16x100 = -11.3 213

CLASSIFICATION OF EXPLOSIVES:Explosives are classified into three categories. : 

CLASSIFICATION OF EXPLOSIVES:Explosives are classified into three categories. 1.Primary or initiating explosives or detonators. 2. Low explosives or propellants. 3. High explosives.

PRIMARY OR INITIATING EXPLOSIVES OR DETONATORS They are highly sensitive explosives. They explode onreceiving a slight shock or by ignition, and have to be very carefully handled. : 

PRIMARY OR INITIATING EXPLOSIVES OR DETONATORS They are highly sensitive explosives. They explode onreceiving a slight shock or by ignition, and have to be very carefully handled.

PREPARATION OF LEAD AZIDE [Pb(N3)2:2NaN3+(CH3COO)2Pb?SOD.AZIDE+LEAD ACETATEPb(N3)2+2CH3COONaLEAD AZIDE+SOD.ACETATE : 

PREPARATION OF LEAD AZIDE [Pb(N3)2:2NaN3+(CH3COO)2Pb?SOD.AZIDE+LEAD ACETATEPb(N3)2+2CH3COONaLEAD AZIDE+SOD.ACETATE

Examples are: Lead azide [Pb(N3)2] : 

Examples are: Lead azide [Pb(N3)2] USES: Due to its low cost, Excellent initiating action and Stability in storage it is very popular for Military uses. DRAWBACKS: Lead azide reacts with brass. Consequently ,the caps loaded with it are made up of aluminium.

PREPARATION OF MERCURY FULMINATE [Hg(ONC)2:Hg+HNO3+C2H5OH?[Hg(ONC)2 Excess ppt. : 

PREPARATION OF MERCURY FULMINATE [Hg(ONC)2:Hg+HNO3+C2H5OH?[Hg(ONC)2 Excess ppt.

Mercury fulminate [Hg(CNO)2] : 

Mercury fulminate [Hg(CNO)2] USES: In comparison to lead azide ,mercury fulminate is more sensitive and expensive. But it is used to a lesser extent because it is slightly toxic.

2.LOW EXPLOSIVES OR DEFLAGRATING OR PROPELLANTS: : 

2.LOW EXPLOSIVES OR DEFLAGRATING OR PROPELLANTS: These are classified into following two categories on the basis of their applications. 1.Military explosives 2.Industrial explosives They only burn and do not explode, like high explosives. They action of low explosives is less shattering and evolve large volume of gas on combustion in a definite and controlled manner.

Examples are:Gun Powder (A mixture of 10% S +15% Charcoal+75% Pot.nitrate : 

Examples are:Gun Powder (A mixture of 10% S +15% Charcoal+75% Pot.nitrate USES: It is an excellent and cheap explosive for blasting down of coal In delay fuses. In shells, igniters and primary assemblers for practice bombs and propellants.

SMOKELESS POWDER (NITROCELLULOSE):C6H7O2(OH)3cellu.+H2SO4+HNO3?C6H7O2(ONO)3+3H2O+H2SO4 Nitrocellulose : 

SMOKELESS POWDER (NITROCELLULOSE):C6H7O2(OH)3cellu.+H2SO4+HNO3?C6H7O2(ONO)3+3H2O+H2SO4 Nitrocellulose USES: It is called smokeless powder because it only produces CO2,CO,N2 water Vapour and almost no smoke

3.HIGH EXPLOSIVES: These are classified into four categories : 

3.HIGH EXPLOSIVES: These are classified into four categories Single compound explosives Binary explosives Plastic explosives Dynamites

1.Single compound explosives It contains only one chemical compound. : 

1.Single compound explosives It contains only one chemical compound. Examples are: Trinitrotoluene (TNT) USES: Due to non-hygroscopic, safe and unreactive with metals to form stable compounds it is mostly used in shell firing and under water explosions.

CH3 : 

CH3 + HNO3 3 ? O2N H2SO4 NO2 CH3 NO2 + H2 O 3

Cyclonite or Cyclotrimethylene trinitroamine or RDX: (CH2)6N4+3HNO3?C3H6O6N6+Hexamethylene tetramine RDX3CH2OFormaldehyde+NH3 : 

Cyclonite or Cyclotrimethylene trinitroamine or RDX: (CH2)6N4+3HNO3?C3H6O6N6+Hexamethylene tetramine RDX3CH2OFormaldehyde+NH3 USES: It is a powerful, high explosive . It is less toxic and more sensitive explosive than TNT. As it is highly sensitive to impact so it is used in practice in combination with TNT.

2.Binary explosivesThey consist of mixture of TNT with other explosives. : 

2.Binary explosivesThey consist of mixture of TNT with other explosives. Examples are: Amatol (TNT+ Ammonium Nitrate 50-80%) USES: It is used as blasting charges in larger caliber shells. It has limited use due to its hygroscopic in nature.

Pentolite (TNT+Pentaerythritol tetra nitrate, 50% each) : 

Pentolite (TNT+Pentaerythritol tetra nitrate, 50% each) USES: The high sensitivity of PETN allows it to be detonated by the impact of a rifle bullet. Widely used in Military warfares.

3.Plastic explosives:These are in combination of high explosive (which provides the destructive power) and wax or oil (which makes high explosive less sensitive and more plastic). : 

3.Plastic explosives:These are in combination of high explosive (which provides the destructive power) and wax or oil (which makes high explosive less sensitive and more plastic).

PENTAERYTHRITOL TETRA NITRATE [C(CH2ONO2)4: Pentaerythritol+96%HNO3?PETN : 

PENTAERYTHRITOL TETRA NITRATE [C(CH2ONO2)4: Pentaerythritol+96%HNO3?PETN USES: They are also used for industrial and military purposes.

4.DynamitesThese are explosives containing Glycerol trinitrate (previously called nitroglycerine)C3H5(ONO2)3.It is an ester, not a nitro compound.Example are:Dynamite it self is an example. : 

4.DynamitesThese are explosives containing Glycerol trinitrate (previously called nitroglycerine)C3H5(ONO2)3.It is an ester, not a nitro compound.Example are:Dynamite it self is an example. USES: For blasting of hard rocks,coal and other minerals and demolitions etc.

Cordite (Cellulose nitrate 65 parts + nitroglycerine 30 parts + Petroleum jelly/Vaseline 5 parts in acetone) : 

Cordite (Cellulose nitrate 65 parts + nitroglycerine 30 parts + Petroleum jelly/Vaseline 5 parts in acetone) USES: The gun cotton slows down the explosive reaction of NG and makes cordite an excellent propellant for larger caliber naval guns.

Exercise:Why detonator is required to explode TNT. : 

Exercise:Why detonator is required to explode TNT.

APPLICATIONS OF EXPLOSIVES:These are categorized under two heads. : 

APPLICATIONS OF EXPLOSIVES:These are categorized under two heads. 1.Destructive Use 2.Constructive Use

1.Destructive Uses : 

1.Destructive Uses For military purposes during times of war.

2.Constructive Uses : 

2.Constructive Uses a. Blasting holes in mountains for the construction of tunnels. b. Excavating earth for dams. c. Drilling oil wells. d. Seismic prospecting. e. Dislodging rocks. f. Quarrying limestone for use in road construction. g. Blasting ores of iron and other metals. h. Breaking down coal. i. Metal forming etc.

Glossary: 1. Velocity of detonation: is the velocity with which the given explosive detonates. Its value depends upon density of powdered explosives. 2. Explosive strength: is the energy liberated per unit mass of the explosive (cal/g) or compared with blasting gelatin (strongest commercial dynamite) on the basis of blasting gelatin is rated 100%. : 

Glossary: 1. Velocity of detonation: is the velocity with which the given explosive detonates. Its value depends upon density of powdered explosives. 2. Explosive strength: is the energy liberated per unit mass of the explosive (cal/g) or compared with blasting gelatin (strongest commercial dynamite) on the basis of blasting gelatin is rated 100%.

3. Brisance refers to the Shattering power of explosive. : 

3. Brisance refers to the Shattering power of explosive.

4. Detonation: is an uncontrolled combustion reaction. A compressive wave travelling with the speed of sound through the explosive heats the explosive mass to its decomposition temperature. By the time, the first shock wave reaches the end of the explosive, the entire explosive would have decomposed, and the full impact of detonation is behind that one wave. : 

4. Detonation: is an uncontrolled combustion reaction. A compressive wave travelling with the speed of sound through the explosive heats the explosive mass to its decomposition temperature. By the time, the first shock wave reaches the end of the explosive, the entire explosive would have decomposed, and the full impact of detonation is behind that one wave.

5. Propellant: is either a high oxygen containing fuel or a mixture of fuel plus oxidant. Its combustion takes place, in a definite and controlled manner with the evolution of a huge volume of gas. : 

5. Propellant: is either a high oxygen containing fuel or a mixture of fuel plus oxidant. Its combustion takes place, in a definite and controlled manner with the evolution of a huge volume of gas.

6. Sensitivity: of an explosive to impact or friction or heat or electric spark or detonator wave. Sensitivity is determined by dropping a standard weight from a height on to the detonator. The lesser the height from which the fall of the standard weight triggering the detonation, better is the sensitivity of the detonator. : 

6. Sensitivity: of an explosive to impact or friction or heat or electric spark or detonator wave. Sensitivity is determined by dropping a standard weight from a height on to the detonator. The lesser the height from which the fall of the standard weight triggering the detonation, better is the sensitivity of the detonator.

REFERENCES : 

REFERENCES ENGINEERING CHEMISTRY BY SHASHI CHAWLA ENGINEERING CHEMISTRY BY JAIN & JAIN ENGINEERING CHEMISTRY BY B.K.SHARMA

THANK YOU : 

THANK YOU N.V.RAVI SHEKHAR