Transcript Slide 1

Chapter 7
Hallucinogens – mostly naturally
occurring substances that can change
normal thought processes,
perceptions, and moods.
Stimulants – act on the nervous
system to make the user feel better
and increase his/her energy/alertness.
Narcotics/analgesics – substances
affecting the central nervous system
to relieve pain.
Depressants – a drug that reduces
excitability and calms a person.
• Toxicology – the study of the adverse
effects of chemicals or physical agents
on living organisms.
Poison Effectiveness
The chemical form of the substance
(pure arsenic versus arsenic trioxide).
Method of entry (oral versus
Condition of victim (weight, age,
general health).
Poison Effectiveness
Time period of exposure
• chronic exposure – continuing
exposure over long periods of time
• acute exposure – large dosage at one
Poison Effectiveness
Presence of other chemicals.
• synergism – combined effect of
substances that exceeds the sum of
their individual effects.
• antagonism – combined effect of
substances that decrease their
individual effects.
Counteracting Poisons
• Chelating agent – an organic
compound that combines with a metal
to form a ring compound.
• Alcohol is the most abused depressant in the
United States.
• The chemical name for alcohol is ethanol or
ethyl alcohol.
• Ethanol, like all alcohols, is toxic.
• Ethanol effects the central nervous system.
• Alcohol circulates in the blood stream
immediately after consumption.
Alcohol and the Law
• The law is concerned with the level of
blood alcohol content (BAC).
• BAC is expressed as a percent weight per
• Federal and Kansas BAC limits are both
0.08 percent.
• This means that there is 0.08 grams of pure
alcohol for every 100 mL of blood.
Alcohol Laws
DUI – driving under the influence
DWI – driving while intoxicated
OUI – operating under the influence
OWI – operating while intoxicated
MIP – minor in possession
Alcohol Processing
• The average person removes 0.015 percent
per hour.
• About 5% of ethanol leaves the body through
respiration, perspiration, and urine.
• About 90% of alcohol is chemically
processed (metabolized) by the liver.
• It is changed first to acetaldehyde (a poison).
• Then it is changed to acetic acid and finally to
carbon dioxide and water.
Alcohol & the Liver
Calculating BAC
0.071 (volum edcon
sum ed, oz)  (%alcohol)
0.085 (volum edcon
sum ed, oz)  (%alcohol)
BAC Affects
0.02 divided attention, slowed reaction time
0.04 Eye movement control
0.05 Coordination
0.06 Judgment
0.08 Concentrated attention, speed control
Breathalyzer Tests
• Henry’s Law - At a constant temperature,
the amount of a given gas dissolved in a
given type and volume of liquid is directly
proportional to the partial pressure of that
gas in equilibrium with that liquid.
• According to Henry’s Law the
concentration of alcohol in the breath is
proportional to the concentration of alcohol
in the blood.
The Chemistry of Breathalyzers
• An orange dichromate ion is reduced to
a green chromium (III) ion.
8H++Cr2O72- +3C2H5OH→