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.
1

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.
2

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.
3

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
4

LABELING

Chemical identity and/or trade name of the hazardous material.

Hazard warning(s).

Name and address of chemical manufacturer.
5

NFPA
704
4
3
W
2
HMIS
6

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
7

Chemical Names with
Potential Hazard
 aluminum
 barium
 chlorine
 copper
 lead
 mercury
8

Word Fragments

-ite

-ate
 nitro-
 acryl-
 chloro-
 isocyan-
9

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”.
10

Corrosive Class Chemicals
 acids (corrosives)
 bases (caustics)
11

Corrosives
CORROSIVES
Acids
HCl
Bases (caustic)
NaOH
Hydrogen ion (
When dissolved in water
-
H )
+
NaOH Na + OH
-
Hydroxide ion ( OH )
12

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
13

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
14

Acid-Base Neutralization
NEUTRALIZATION
Mixing an Acid with a Base
+ +
HCl + NaOH H + Cl + Na + OH
-
+ + -
H + Cl + Na + OH NaCl + HOH + Energy
Acid + Base Salt + Water + Heat
The energy or heat may be sufficient to cause a violent reaction releasing toxic vapors and/or irritating gases.
15

Strong vs Weak
Strength of a Corrosive: is the % dissociation of the corrosive when mixed with water.
HCl 100%
+
H & Cl
( Strong : 100% dissociation)
-
CH
3
+
COOH 2% H & CH
3
-
COO + 98% CH
3
COOH
( Weak : only 2% dissociation)

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
17

Strength vs Concentration
 strong vs weak
• amount of dissociation
 concentrated vs dilute
• amount of additional solvent (H
2
O)
18

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
19

Corrosive Hazards

Vapor - far reaching
• Inhalation

Liquid
• skin/eye contact - splash

Solid
• Inhalation of dust
• skin/eye contact
20

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
21

Treatment for Skin Exposure
 flush with water:
• physically remove corrosive
• dilution of corrosive
22

Hazardous Mixtures

Corrosives and Poisons
• release toxic gases

Corrosives and Ignitable Materials
• many possible reactions depending on chemicals
• some corrosion are oxidizers
23

Hazardous Mixtures

Corrosives and Water
• violent reaction
• generation of heat
• production of a vapor cloud
• over-pressurization of container

Corrosives and Metal
• destruction of metal
Never store corrosives in a metal container!
• production of hydrogen gas
HOT
24

Polychlorinated Biphenyls - PCBs
 found in plants, animals, and soil around the world
 transported throughout the biosphere by several pathways
 suspected human carcinogen
25

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.)
26

Solvent Hazards

Primary Hazard
• Chemical Physical hazard

Secondary hazard
• Chemical Health hazard
27

Fire and Explosion

Oxidizer

Fuel

Ignition source
28

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
29

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
30

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
31

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.
32

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.
33

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.
34

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.
35

Treatment for Solvent Exposure
 wash skin with soap and water

15 minute flush at a minimum
36

Oxidizers
 oxidizing elements
• O
2
, Cl
2
 oxysalts
• NO
3
, ClO
3
 inorganic peroxides
 certain acids
 organic peroxides
37

Hazards of Oxidizers
 intensify combustion
 spontaneous ignition
 explosion
 produce toxic fumes
 gaseous oxidizers
38

Water Reactive Metals
 lithium
 sodium
 potassium
 beryllium
 magnesium
 calcium
39

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
40

Explosives
Main
Charge
 igniter
 primer
 detonator
 booster charge
 main charge
Booster
Charge
Detonator
Primer
Igniter
41