PCC 274 Midterm Exam 2 Textbook Information

Excretion, p. 301

Elimination of alcohol from the body in an unchanged state; alcohol is normally excreted in breath and urine

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Horizontal-gaze nystagmus, walk and turn, and the one-leg stand constitute a series of reliable and effective psychophysical tests.

Oxidation, p. 301

The combination of oxygen with other substances to produce new products

Wavelength, p. 215

The distance between crests of adjacent waves

Electromagnetic Spectrum, p. 215

The entire range of radiation energy from the most energetic cosmic rays to the least energetic radio waves

Frequency, p. 215

The number of waves that pass a given point per second

Compound, p. 204

A pure substance composed of two or more elements

Periodic Table, p. 204

A chart of elements arranged in a systematic fashion; vertical rows are called groups or families, and horizontal rows are called series; elements in a given row have similar properties

Vein, p. 304

A blood vessel that transports blood toward the heart

Becke Line, p. 219

A bright halo that is observed near the border of a particle immersed in a liquid of a different refractive index

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A chemical property describes the behavior of a substance when it reacts or combines with another substance.

Absorption, p. 301

Passage of alcohol across the wall of the stomach and small intestine into the bloodstream

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Crystalline solids have definite geometric forms because of the orderly arrangement of the fundamental particle of a solid, the atom.

Artery, p. 304

A blood vessel that carries blood away from the heart

Base, p. 315

A compound capable of accepting a hydrogen ion (H+)

Acid, p. 315

A compound capable of donating a hydrogen ion (H+) to another compound

Physical State, p. 207

A condition or stage in the form of matter; a solid, liquid, or gas

Mass, p. 212

A constant property of matter that reflects the amount of material present

Radial Fracture, p. 223

A crack in a glass that extends outward like the spoke of a wheel from the point at which the glass was struck

Concentric Fracture, p. 223

A crack in a glass that forms a rough circle around the point of impact

Fuel Cell Detector, p. 305

A detector in which chemical reactions produce electricity

Monochromator, p. 287

A device for isolating individual wavelengths or frequencies of light

Birefringence, p. 214

A difference in the two indices of refraction exhibited by most crystalline materials

Summary

A drug can be defined as a natural or synthetic substance that is used to produce physiological or psychological effects in humans or other higher-order animals.

Analgesic, p. 263

A drug or substance that lessens or eliminates pain

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A fracture always terminates at an existing line of fracture.

Element, p. 204

A fundamental particle of matter; an element cannot be broken down into simpler substances by chemical means

X-Ray, p. 215

A high-energy, short-wavelength form of electromagnetic radiation

Sublimation, p. 207

A physical change from the solid state directly into the gaseous state

Density, p. 209

A physical property of matter that is equivalent to the mass per unit volume of a substance

Weight, p. 212

A property of matter that depends on both the mass of a substance and the effects of gravity on that mass

Intensive Property, p. 209

A property that is not dependent on the size of an object

pH Scale, p. 316

A scale used to express the basicity or acidity of a substance; a pH of 7 is neutral, whereas lower values are acidic and higher values are basic

Confirmation, p. 277

A single test that specifically identifies a substance

Photon, p. 216

A small packet of electromagnetic radiation energy; each photon contains a unit of energy equal to the product of Planck's constant and the frequency of radiation: E = hf

Crystalline Solid, p. 213

A solid in which the constituent atoms have a regular arrangement

Amorphous Solid, p. 213

A solid in which the constituent atoms or molecules are arranged in random or disordered positions; there is no regular order in amorphous solids

Liquid, p. 207

A state of matter in which molecules are in contact with one another but are not rigidly held in place

Gas (Vapor), p. 207

A state of matter in which the attractive forces between molecules are small enough to permit them to move with complete freedom

Solid, p. 207

A state of matter in which the molecules are held closely together in a rigid state

Stimulant, p. 270

A substance taken to increase alertness or activity

Depressant, p. 269

A substance that depresses the functions of the central nervous system; depressants calm irritability and anxiety and may induce sleep

Hallucinogen, p. 265

A substance that induces changes in mood, attitude, thought processes, and perceptions

Anticoagulant, p. 310

A substance that prevents coagulation or clotting of the blood

Preservative, p. 310

A substance that stops the growth of microorganisms in blood

Screening Test, p. 277

A test that is nonspecific and preliminary in nature

Capillary, p. 304

A tiny blood vessel across whose walls exchange of materials between the blood and the tissues takes place; it receives blood from arteries and carries it to veins

Phase, p. 207

A uniform body of matter; different phases are separated by definite visible boundaries

Matter, p. 204

All things of a substance; matter is composed of atoms or molecules

Laser, p. 216

An acronym for light amplification by stimulated emission of radiation; light that has all its waves pulsating in unison

Narcotic, p. 262

An analgesic or painkilling substance that depresses vital body functions such as blood pressure, pulse rate, and breathing rate; regular administration of narcotics produces physical dependence

Spectrophotometry, p. 287

An analytical method for identifying a substance by its selective absorption of different wavelengths of light

Ion, p. 290

An atom or molecule bearing a positive or negative charge

Toxicologist, p. 313

An individual charged with the responsibility of detecting and identifying the presence of drugs and poisons in body fluids, tissues, and organs

Chromatography, p. 279

Any of several analytical techniques for separating organic or carbon containing mixtures into their components by attraction to a stationary phase while being propelled by a moving phase

Summary

By analyzing the radial and concentric fracture patterns in glass, the forensic scientist can determine the direction of impact. This can be accomplished by applying the 3R rule: Radial cracks form a Right angle on the Reverse side of the force.

Summary

Chromatography, spectrophotometry, and mass spectrometry are all readily used by a forensic scientist to identify or compare organic or carbon containing materials. Chromatography is a means of separating and tentatively identifying the components of a mixture. Spectrophotometry is the study of the absorption of light by chemical substances. Mass spectrometry characterizes molecules by observing their fragmentation pattern after their collision with a beam of high-energy electrons. Gas chromatography (GC) separates mixtures on the basis of their distribution between a stationary liquid phase and a mobile gas phase. In GC, the moving phase is actually a gas called the carrier gas, which flows through a column. After a mixture has traversed the length of the column, it emerges separated into its components. The written record of this separation is called a chromatogram. A direct connection between the GC column and the mass spectrometer allows each component to flow into the mass spectrometer as it emerges from the GC. Fragmentation of each component by high-energy electrons produces a "fingerprint" pattern of the substance being examined.

Visible Light, p. 214

Colored light ranging from red to violet in the electromagnetic spectrum

Psychological Dependence, p. 260

Conditioned use of a drug caused by underlying emotional needs

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Density is defined as mass per unit volume.

Summary

Depressants are another class of drugs. These include alcohol (ethanol), barbiturates, tranquilizers, and various substances that can be sniffed, such as airplane glue and model cement. Stimulants include amphetamines, sometimes known as "uppers" or "speed," and cocaine, which in its freebase form is known as crack. The term club drugs refers to synthetic drugs that are used at nightclubs, bars, and raves (all-night dance parties). Substances that are often used as club drugs include, but are not limited to, MDMA (Ecstasy), GHB (gamma hydroxybutyrate), Rohypnol ("roofies"), ketamine, and methamphetamine. Yet another category of drugs is anabolic steroids, which are synthetic compounds chemically related to the male sex hormone testosterone. Anabolic steroids are often abused by individuals who want to accelerate muscle growth. Federal law establishes five schedules of classification for controlled dangerous substances on the basis of a drug's potential for abuse, potential for physical and psychological dependence, and medical value.

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Different materials always have distinctively different infrared spectra; each IR spectrum is therefore equivalent to a "fingerprint" of that substance and no other.

Summary

Dispersion is the process of separating light into its component colors. Each component bends, or refracts, at a different angle as it emerges from a prism. The large family of radiation waves is known as the electromagnetic spectrum. Two simple models explain light's behavior. The first model describes light as a continuous wave; the second depicts light as a stream of energy particles.

Summary

Faced with the prospect that the unknown substance may be any one of a thousand or more commonly encountered drugs, the analyst must employ screening tests to reduce these possibilities to a small and manageable number. Another consideration in selecting an analytical technique is the need for either a qualitative or a quantitative determination. The former relates just to the identity of the material, whereas the latter requires the determination of the percentage composition of the components of a mixture.

Tempered Glass, p. 217

Glass that is strengthened by introducing stress through rapid heating and cooling of the glass surfaces

Ultraviolet, p. 287

Invisible high frequencies of light beyond violet in the visible spectrum

Infrared, p. 290

Invisible short frequencies of light before red in the visible spectrum

Monochromatic Light, p. 287

Light having a single wavelength or frequency

Summary

Narcotic drugs are analgesics, meaning they relieve pain by depressing the central nervous system. Regular use of a narcotic drug leads to physical dependence. The most common source of narcotic drugs is opium. Morphine is readily extracted from opium and is used to synthesize heroin. Opiates, which include methadone and OxyContin (oxycodone), are not derived from opium or morphine, but they have the same physiological effects on the body as do opium narcotics. Another class of drugs is hallucinogens; marijuana is the most well-known member of this class. Hallucinogens cause marked changes in mood, attitude, thought processes, and perceptions. Marijuana is the most controversial drug in this class because its long-term effects on health are still largely unknown. Other hallucinogens include LSD, mescaline, PCP, psilocybin, and MDMA (Ecstasy).

Physical Dependence, p. 260

Need for a drug that has been brought about by its regular use; dependence is characterized by withdrawal sickness when administration of the drug is abruptly stopped

Summary

Other forms of chromatography applicable to forensic science are high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). HPLC separates compounds using a stationary phase and a mobile liquid phase and is used with temperature-sensitive compounds. TLC uses a solid stationary phase, usually coated onto a glass plate, and a mobile liquid phase to separate the components of the mixture. Most forensic laboratories use ultraviolet (UV) and infrared (IR) spectrophotometers to characterize chemical compounds. In contrast to the simplicity of a UV spectrum, absorption in the infrared region provides a far more complex pattern. Different materials always have distinctively different infrared spectra; each IR spectrum is therefore equivalent to a "fingerprint" of that substance. This objective is often accomplished by subjecting the material to a series of color tests that produce characteristic colors for the more commonly encountered illicit drugs. Once this preliminary analysis is completed, a confirmation is pursued. Forensic chemists use a specific test to identify a drug substance to the exclusion of all other known chemical substances. Typically infrared spectrophotometry or mass spectrometry is used to specifically identify a drug substance.

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Physical properties describe a substance without reference to any other substance.

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Preliminary, or field sobriety, tests are normally performed to ascertain the degree of the suspect's physical impairment and whether an evidential test is justified.

Chemical Property, p. 204

The behavior of a substance when it reacts or combines with another substance

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Radial cracks form a Right angle on the Reverse side of the force.

Alveoli, p. 304

Small sacs in the lungs through whose walls air and other vapors are exchanged between the breath and the blood

Physical Property, p. 204

The behavior of a substance without alteration of the substance's composition through a chemical reaction

Refraction, p. 212

The bending of a light wave as it passes from one medium to another

Anabolic Steroids, p. 273

Steroids that promote muscle growth

Microcrystalline Tests, p. 278

Tests to identify specific substances by the color and morphology of the crystals formed when the substance is mixed with specific reagents

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The fate of alcohol in the body is relatively simple - namely, absorption into the bloodstream, distribution throughout the body's water, and finally, elimination by oxidation and excretion. The elimination, or "burn-off," rate of alcohol varies in different individuals; 0.015 percent w/v (weight per volume) per hour is the average rate after the absorption process is complete. However, this figure is an average that varies by as much as 30 percent among individuals.

Summary

The flotation and immersion methods are best used to determine a glass fragment's density and refractive index, respectively. In the flotation method, a glass particle is immersed in a liquid. The density of the liquid is carefully adjusted by the addition of small amounts of an appropriate liquid until the glass chip remains suspended in the liquid medium. At this point, the glass will have the same density as the liquid medium and can be compared to other relevant pieces of glass. The immersion method involves immersing a glass particle in a liquid medium whose refractive index is varied until it is equal to that of the glass particle. At this point, known as the match point, minimum contrast between liquid and particle is observed.

Summary

The forensic scientist must constantly determine the properties that impart distinguishing characteristics to matter, giving it a unique identity. Physical properties such as weight, volume, color, boiling point, and melting point describe a substance without reference to any other substance. A chemical property describes the behavior of a substance when it reacts or combines with another substance. Scientists throughout the world use the metric system of measurement. The metric system has basic units of measurement for length, mass, and volume: the meter, gram, and liter, respectively. Temperature is a measure of heat intensity, or the amount of heat in a substance. In science, the most commonly used temperature scale is the Celsius scale. This scale is derived by assigning the freezing point of water a value of 0ºC and its boiling point a value of 100ºC.

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The physical properties of density and refractive index are most widely used for characterizing glass particles.

Refractive Index, p. 213

The ratio of the speed of light in a vacuum to its speed in a given substance

Dispersion, p. 214

The separation of light into its component wavelengths

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The smallest particle of an element that can exist and still retain its identity as that element is the atom.

Atom, p. 213

The smallest unit of an element, which is not divisible by ordinary chemical means; atoms are made up of electrons, protons, and neutrons plus other subatomic particles

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The temperature at which breath leaves the mouth is normally 34ºC. At this temperature, experimental evidence has shown that the ratio of alcohol in the blood to alcohol in alveoli air is approximately 2,100 to 1. In other words, 1 milliliter of blood will contain nearly the same amount of alcohol as 2,100 milliliters of alveolar breath. Henry's law thus becomes a basis for relating breath to blood-alcohol concentration.

Celsius Scale, p. 209

The temperature scale using the melting point of ice as 0º and the boiling point of water as 100º, with 100 equal divisions or degrees between

Fahrenheit Scale, p. 209

The temperature scale using the melting point of ice as 32º and the boiling point of water as 212º, with 180 equal divisions or degrees between

Metabolism, p. 300

The transformation of a chemical in the body to another chemical to facilitate its elimination from the body

Laminated Glass, p. 217

Two sheets of ordinary glass bonded together with a layer of plastic

Summary

To compare glass fragments, a forensic scientist evaluates two important physical properties: density and refractive index. Density is defined as the mass per unit volume. Refractive index is the ratio of the velocity of light in a vacuum to that in the medium under examination. Crystalline solids have definite geometric forms because of the orderly arrangement of their atoms. These solids refract a beam of light in two different light-ray components. This results in double refraction. Birefringence is the numerical difference between these two refractive indices. Not all solids are crystalline in nature. For example, glass has a random arrangement of atoms that forms an amorphous or noncrystalline solid.

Fluoresce, p. 285

To emit visible light when exposed to light of a shorter wavelength - that is, ultraviolet light

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When a volatile chemical (alcohol) is dissolved in a liquid (blood) and is brought to equilibrium with air (alveolar breath), there is a fixed ratio between the concentration of the volatile compound (alcohol) in air (alveolar breath) and its concentration in the liquid (blood), and this ratio is constant for a given temperature.

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Whenever substances can be distinguished by a visible boundary, different phases are said to exist.