Chapter 5 Review PART II: EXPLOSIVES

Kinetic Molecular Theory of Gases— (Recognize the parts)  Gases are made up of many particles moving in rapid, random motion  Most of the volume of a gas is empty space  When gas particles collide with each other or the container, they do not lose energy  There is no force of attraction between gas particles or between the particles and their container  As temperature increases, so does the average kinetic energy of the gas particles

Properties of Gas 3

Concept check: IF temperature increases and volume is constant then…. A. Pressure decreases B. Pressure increases C. Pressure stays constant D. None of the above

Concept Check: If volume increases, and temperature is constant then…. A. Pressure decreases B. Pressure increases C. Pressure stays constant D. None of the above

Combined Gas Law P 1 x V 1 = P 2 x V 2 T 1 T 2

Concept Check You have a helium-filled balloon on a warm day. The temperature is 300 K. The volume of the balloon is 25 L. The pressure is kPa. Now, imagine that you carry the balloon into your air-conditioned home. The temperature changes to 293 K and the pressure remains constant. What is the new volume of the balloon?

Answer: V2 = L

Explain the procedures for determining the identity of an explosive 1. Microscopic examination ◦Unexploded material—Ex. smokeless powder ◦Pieces of explosive device ◦ Ex. wrapper from dynamite, metal from a pipe, pieces of wire, shrapnel 2. Presumptive tests ◦Color Spot tests ◦Thin Layer Chromatography (TLC) 3. Confirmatory tests ◦Gas chromatography/mass spectroscopy

Color Spot Tests 10 Presumptive Tests

How does a color spot test work? Wash explosive debris with acetone because it dissolves the explosives easily. The mixture is then mixed with a reagent (Griess, KOH, dipenylamine) and depending on the color, it narrows down the explosive.

COLOR SPOT TESTS Modified Griess Test—tests for presence of NITRITE compounds – turns ORANGE Alcoholic Potassium Hydroxide (KOH)—tests for TNT only-- Turns RED TO VIOLET Diphenylamine—tests for most explosives (except TNT and RDX) Turns BLUE/BLACK

Thin Layer Chromatography (TLC) Presumptive Tests ◦R f values from TLC provide tentative identification of the components of the mixture ◦A cellulose or silica gel plate as the stationary phase

Confirmatory Tests Both use physical properties of samples to identify the explosives:  Infrared spectroscopy  Gas chromatography/mass spectroscopy

High Explosives Vs. Low Explosives High explosives: -detonate easily - produce pressure waves up to 8500 m/s - don’t need to be confined to detonate Low explosives: - need to be in a confined space to explode - produce pressure waves of less than 340 m/s - often used as propellants

The pressure wave that spreads rapidly away from high explosives is called a: A. longitudinal wave B. compression C. rarefaction D. shock wave

Materials that burn rapidly but explode only when confined in a container are called? A) Low Explosive B) High Explosive C) Deflagration D) Medium Explosive

Low explosives are often uses as what? A) Deflagration B) Propellants C) Compressions D) Waves

______ detonates easily and produces a pressure wave that moves a fast as 8,500 m/s A) High Explosive B) Medium Explosive C) Low Explosive D) Extreme Explosive

Question… Give an example of a high explosive and low explosive.

High explosive: - TNT - dynamite - nitroglycerin Low explosive: - fireworks - warning flares - smokeless gunpowder or black powder

What is the difference between Primary High Explosives and Secondary High Explosives?

High Explosives Primary  extremely sensitive to heat, pressure and movement (too volatile for most uses) nitroglycerine Secondary  not as sensitive to shock and heat Can cause very violent explosions Military explosives: PTEN + TNT—granades, small projectiles RDX: pliable plastic, C-4 Commercial: mining, road construction, demolition Black powder, dynamite, ANFO

Collection of evidence Why can collecting evidence be dangerous? Because shards of glass or sharp pieces of metal may be left after the explosion. Toxic or flammable vapors remain in the air after explosions and there’s always a risk that a second explosion device could detonate.

Terrorism cont. Why are terrorist attacks designed? A.To cause damage to others homes B.To cause injury & death C.To take over the world D.All of the above