Transcript Chemistry - Brownfields Toolbox

Chemistry
Instructional Goal: upon completion of
this topic, the student will have a
better understanding of potentially
hazardous
situations
involving
corrosives, solvents, oxidizers, and
reactive chemicals.
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Chemical Awareness
 Hazardous
substances are used in
business and industry. A basic knowledge
of chemical hazard classes, chemical
terms, and a basic chemical hazard
awareness is required by OSHA.
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HAZARD COMMUNICATION STANDARD
29 CFR 1910.1200
The employer’s Haz Com program must include:
 Conduct
a chemical inventory.
 Obtain and file MSDSs for all chemicals.
 Label all containers.
 Train employees about the hazards.
 The Haz Com program must be written and
available to employees.
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Material Data Safety Sheet
 Product ID and manufacturer name
 Hazardous ingredients
 Physical / chemical characteristics
 Fire and explosion hazard data
 Reactivity data
 Health hazard data
 Safe handling and use
 Control measures
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LABELING
 Chemical identity and/or
trade name of the
hazardous material.
 Hazard warning(s).
 Name and address of
chemical manufacturer.
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LABELING
NFPA
704
3
4
2
W
HMIS
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Chemical Awareness
 Chemical names and terms can be
very confusing and misleading, but
can alert a worker to a chemical that
has a potential to harm.
 Chemical names and hazards must
be verified with an MSDS or other
such source
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Chemical Names with
Potential Hazard
 aluminum
 barium
 chlorine
 copper
 lead
 mercury
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Word Fragments
 -ite
 -ate
 nitro acryl-
 chloro isocyan-
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Corrosive Class Chemicals
Corrosives are the second most
commonly used and transported group
of hazardous materials.
A corrosive material is defined as
“any liquid that has a severe
corrosion rate on steel”.
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Corrosive Class Chemicals
 acids (corrosives)
 bases (caustics)
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Corrosives
CORROSIVES
Acids
Bases (caustic)
HCl
NaOH
When dissolved in water
HCl
H + + Cl
Hydrogen ion (H +)
-
NaOH
+
Na +
Hydroxide ion
OH
(OH- )
-
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Chemical Awareness
 pH range is from 0 - 14
 Acids
• low pH number
• high concentration of (H+) ions
 Bases
• high pH number
• low concentration of (H+ ) ions
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pH Scale
Neutral
Acid
Base
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Increasing strength ( H+ )
_
Increasing strength (OH )
pH Scale
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Acid-Base Neutralization
NEUTRALIZATION
Mixing an Acid with a Base
HCl + NaOH
H
+
+
Acid
-
Cl +
+
Na
H
+
+ OH
Base
-
+
-
+ Cl +
+
Na
+ OH
-
NaCl
+
HOH + Energy
Salt
+ Water + Heat
The energy or heat may be sufficient to
cause a violent reaction releasing toxic
vapors and/or irritating gases.
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Strong vs Weak
Strength of a Corrosive: is the % dissociation
of the corrosive when mixed with water.
HCl
100% H
+
& Cl
-
(Strong: 100% dissociation)
+
CH3 COOH
2% H & CH3COO
(Weak: only 2% dissociation)
-
+ 98% CH3COOH
CONCENTRATION
• Percent
• Molar
The amount of material in a given
volume of water.
The larger the number before the
term the more concentrated the
solution.
1M soln > 0.1M soln
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Strength vs Concentration
 strong vs weak
• amount of dissociation
 concentrated vs dilute
• amount of additional
solvent (H2O)
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Corrosive Hazards
 destroy living tissue
 chemical burn is 9 times more damaging
than a thermal burn
 extent of injury from corrosive exposure:
•
•
•
•
concentration of corrosive
quantity of corrosive
body area affected
duration of contact
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Corrosive Hazards
 Vapor - far reaching
• Inhalation
 Liquid
• skin/eye contact - splash
 Solid
• Inhalation of dust
• skin/eye contact
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Protective Measures
 common exposures and protection
•
•
•
•
•
hands - gloves
nose, throat, airway - respirator
feet - closed toe shoes
face - faceshield
eyes - goggles or glasses with side-shields
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Treatment for Skin Exposure
 flush with water:
• physically remove corrosive
• dilution of corrosive
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Hazardous Mixtures
 Corrosives and Poisons
• release toxic gases
 Corrosives and Ignitable Materials
• many possible reactions depending on
chemicals
• some corrosion are oxidizers
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Hazardous Mixtures
 Corrosives and Water
•
•
•
•
violent reaction
generation of heat
production of a vapor cloud
over-pressurization of container
HOT
 Corrosives and Metal
• destruction of metal
Never store corrosives in a metal container!
• production of hydrogen gas
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Polychlorinated Biphenyls - PCBs
 found in plants, animals, and
soil around the world
 transported throughout the
biosphere by several
pathways
 suspected human
carcinogen
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Solvents
 halogenated
solvents
– hydrocarbon solvents that contain
one or more halogen atoms (Cl, F, or
Br) attached to the hydrocarbon
molecule.
 flammable solvents
• A hydrocarbon solvent having a
flashpoint below 100 deg. F. (37.8 deg.
C.)
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Solvent Hazards
 Primary Hazard
• Chemical Physical hazard
 Secondary hazard
• Chemical Health hazard
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Fire and Explosion
 Oxidizer
 Fuel
 Ignition source
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Acute Health Hazards
 Inhalation
• Nausea
• Headaches and drowsiness
• Irritation of mucous membranes of the
respiratory passage
• Muscular weakness
• Loss of coordination
• Disorientation and confusion
• Unconsciousness and sometimes death
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Acute Health Hazards
• Skin/eye contact
 Removal of skin oils resulting in irritation
 Cracking and Rashes on the skin
 Dermatitis
 Burning and Irritation of eyes
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Do’s for Solvents

Read the container label and MSDS
before you use the chemical.

Keep the work area clean. Fewer spills happen in
clean work areas.

Use protective clothing and equipment when
• operating procedures call for them
• MSDS recommends it
• over-exposures are detected or expected
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Do’s for Solvents

Use only approved and labeled containers for
storing and transporting solvents.

Make sure there is proper ventilation when
using solvents.

Keep flammables away from heat and ignition
sources.

Check that containers and hoses are in good
working condition.
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Don’ts for Solvents
 DON'T leave containers open when not in use.
 DON'T siphon by mouth.
 DON'T depend on a "funny smell" to detect
hazardous gases in the air - some are odorless.
 DON'T breathe gases produced from chemical
reactions.
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Don’ts for Solvents
 DON'T mix solvents - unless instructed to; follow
instructions exactly and double check
 DON'T smoke, eat or drink around hazardous
substances.
 DON'T wear contact lenses around toxic vapors.
 DON'T track hazardous materials from one
location to the next.
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Don’ts for Solvents
 DON'T store hazardous chemicals next
to each other without checking the
MSDS for possible reactions.
 DON'T work by yourself; have someone
nearby who knows where you are and
what you're doing at all times.
 DON'T cut corners on hazardous
substance handling procedures.
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Treatment for Solvent Exposure
 wash skin with soap and water
 15 minute flush at a minimum
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Oxidizers
 oxidizing elements
• O2, Cl2
 oxysalts
• NO3, ClO3
 inorganic peroxides
 certain acids
 organic peroxides
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Hazards of Oxidizers
 intensify combustion
 spontaneous ignition
 explosion
 produce toxic fumes

gaseous oxidizers
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Water Reactive Metals
 lithium
 sodium
 potassium
 beryllium
 magnesium
 calcium
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Unstable Materials
Unstable is defined as any material that
will spontaneously decompose,
polymerize, or self-react under conditions
of shock, temperature, or pressure
 Alkali Metals - Na, K, Li
 Organic peroxides - acetyl peroxide, MEK
peroxide
 Monomers - styrene, vinyl chloride
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Explosives
 igniter
 primer
 detonator
 booster charge
 main charge
Main
Charge
Booster
Charge
Detonator
Primer
Igniter
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