Chemistry for CUPA Inspectors

11 th CA Unified Program Annual Training Conference March 28, 2009

Jojo Comandante Hazardous Materials Specialist Los Angeles County Fire Department 323-890-4041

BASIC CHEMISTRY REVIEW

 Chemistry, definition – the study of matter and the changes it undergoes Matter Elements Pure Substances Mixtures Compounds Solutions Suspensions Heterogeneous Mixtures

PROPERTIES OF MATTER  Physical: describes the response of the substance to some external influence, such as heat, light, force, etc.

 Chemical: describes the interaction of the substance with another  Vapor Pressure: at 20 O C water has a V P = Acetone VP = 65 % Sulfuric Acid = 18 mm Hg 182 mm Hg 1.6 mm Hg

SPECIFIC GRAVITY

 unitless, because it is a ratio of densities; compares the density of a liquid or a gas with a reference material  For liquids, reference is water Water density at 20 O C = 1 g/ml or 8.34 lb/gal  For gases, reference is air Air density at 20 O C = 1.21 g/L or 0.075 lb/cu.ft.

 Some MSDS’s list the specific gravity as the density.

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SPECIFIC VOLUME

volume per unit mass, or the inverse of density.

ELEMENTS  The Periodic Table  Atomic weight vs. atomic number: Ex. Carbon has atomic number of 6, weight of 12  Family (Group) vs. Period     Oxidation states Charges the ions carry, positive (cations) or negative (anions) Free elements carry zero charge Depends on group in periodic table Some may exhibit more than two oxidation states

COMPOUNDS

 Formed based on the octet rule  Bonds may be ionic or covalent  There are rules in naming compounds 1.

Organic compounds follow the sequential prefix meth, eth, prop, but, etc.

2.

3.

4.

Root names of organic compounds based on the longest C-C chain, plus the functional groups.

Inorganic binary salts end in –ide, such as sodium chloride.

Oxysalts end in hypo –ate for the normal ion; per—ate for one more oxygen atom; -ite for one oxygen less; —ite for two oxygen atoms less

SOLUTIONS 

Solute vs. solvent

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Types of solutions based on solute and solvent : solid in liquid, liquid in liquid, gas in liquid, solid in solid, etc.

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Expressing concentrations

CALCULATIONS IN HAZMAT CHEMISTRY

      Involves concentrations of contaminant in environment, or of a solute in a solvent % concentrations by weight or by volume: Weight of solute X 100; Volume of solute X 100 Weight of solution Volume of solution Molarity – moles of solute per liter of solution; important in the expression of pH pH – negative logarithm of the hydrogen ion concentration expressed in moles per liter molality – moles of solute per kilogram of solvent; important in determining the change in colligative properties of solutions parts per million – weight of the contaminant per million weight parts of the mixture.

DIMENSIONAL ANALYSIS

 Be familiar with the prefixes: tera- 10 12 giga- 10 9 mega- 10 6 kilo- 10 3 hecto- 10 2 deca- 10 1 pico- 10 -12 nano- 10 -9 micro- 10 -6 milli- 10 -3 centi- 10 -2 deci- 10 -1  For ppm, any combination that will lead to a difference of 6 powers of ten is the ppm.

Ex. 3 gms of arsenic in 1 megagram of solution is 3 ppm 5 mL of HCl in 1 kiloliter of solution is 5 ppm 7 micrograms of meth in 1 gram of mixture is 7 ppm

  Question: An aqueous solution of 100 mL contains 0.02 gm of sulfuric acid. What is the ppm?

Answer: Assuming a density of 1g/mL, 100 mL is equivalent to 100 gms, and 0.02 gm is 20 mg or 20000 microgm. Divide 20000 microgm by 100 gm and you get 200 microgm per gm of solution. Answer is therefore 200 ppm.

  Question: The LEL of benzene is 1.1 %. Should you enter a room with a known benzene atmosphere when your 4-gas meter reads 2200 ppm?

Answer: 1.1 % is 11,000 ppm. The safety factor for entry is 10% of LEL. 10% of 11000 is 1100. Since the room is 2200 ppm, then the answer is no, you should not enter the room.

 Be familiar with conversion factors, English to metric and vice versa.

Ex.

1 inch = 2.54 cm 1 gal = 3.785 liters; 1 cu ft = 7.481 gals 1 pound = 454 grams  Be aware that you multiply and divide so you can cancel units as numerator and denominator.

Ex. 1 g X 1000mL X 3.785 L X 1 lb = 8.34 lbs mL 1 L 1 gal 454 gm gal

 Estimation of Vapor Density based on ideal gas law PV = nRT P(MW) = ρRT where ρ = density and MW = molecular weight  Average MW of air is 29  If MW of contaminant is greater than 29, will most likely behave as a heavy gas  Assuming ideal gas behavior, conversion of g/m3 into ppm: g/m 3 = ppm X MW 24,500

 Question: 0.5 lb of chlorine was released inside a 10,000 sq ft warehouse with a 12 ft. ceiling height. Assuming chlorine behaves as an ideal gas and it mixes homogeneously with air in the room, what is the ppm concentration?

 Answer: Convert 0.5 lbs; X 454 = 227 gms.

Convert 120,000 cu ft; X [12 in/ft X 0.0254 m/ in] 3 3398 m 3 g/m 3 = 227 ÷ 3398 = 0.0668 ppm = (0.0668 X 24, 500) ÷71 = 23 ppm IDLH = 10 ppm =

BUFFER SOLUTIONS

 A

buffer solution

is an aqueous solution consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. It has the property that the pH of the solution changes very little when a small amount of acid or base is added to it. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications.

REACTION CHEMISTRY  Types of chemical reactions a.

Synthesis or direct combination: A + B  AB b. Decomposition: AB  A + B c.

d.

Single Displacement or Substitution: A + BC  AC + B Double Displacement: AB + CD  AD + BC e.

Acid-Base Reaction: HCl + NaOH  NaCl + HOH (water) f.

g.

h.

Oxidation-reduction (Redox): 2 S 2 O 3 2 (aq) + I 2  S 4 O 6 2 Combustion: (aq) + 2 I Special redox reaction (aq) Organic reactions too many to mention

OXIDATION REDUCTION (REDOX)

    Involves a change in oxidation state (charge) Reminder: Oxidation state of free elements is zero. Some elements may exhibit more than 2 oxidation states.

GEROA – the oxidizing agent (oxidizer) gains electrons and is therefore reduced (the charge decreases: Oxygen from zero to negative 2) Non-metals act as oxidizer; metals act as reducing agents Group I metals react violently when oxidized  Activity series of elements a.

b.

c.

Elements which release Hydrogen from water: Cesium, Lithium, Rubidium, Potassium, Barium, Sodium, Calcium, Magnesium Elements which release Hydrogen from acids: Aluminum, Manganese, Zinc, Chromium, Iron, Nickel, Tin, Lead Elements which do not release Hydrogen from acids: Bismuth, Copper, Mercury, Silver, Platinum, Gold

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COMBUSTION

Slow versus Rapid: Rapid combustion releases large amounts of heat and light energy, resulting in fire. In addition, gases may also be evolved. Sudden evolution of gases creates excessive pressure – EXPLOSION!

Slow Combustion takes place at low temperatures. It occurs at the molecular level. Cellular respiration is an example.

 Complete versus Incomplete In complete combustion, all the elements in the fuel yield the most common oxides – carbon dioxide, sulfur dioxide, nitrogen dioxide, and water.

Incomplete combustion occurs when there isn’t enough oxygen to allow the fuel to react completely. The products of combustion may include carbon monoxide, unburned carbon or soot, and lower hydrocarbons.

 Combustion in air will result in nitrogen or oxides of nitrogen in the flue gas.

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CASE STUDIES

Hydrogen Peroxide spill Aluminum Powder Anhydrous Ammonia Release Spontaneous Combustion

HYDROGEN PEROXIDE SPILL

     Smoke coming out of delivery truck 50% hydrogen peroxide spilled from drum and reacted with wooden flooring of truck Freeway closed Leaking drum behind other items for delivery Challenge: Initial entry team in level A or level B?

RESOLUTION

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Hydrogen peroxide can remain as peroxide in vapor state

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Level A for the entry team Forklift used to locate leaking drum Overpack leaking drum Truck vented

ALUMINUM POWDER

      30 lb. container of aluminum powder found in foreclosed home Container clearly marked “Keep Away From Water” Literature on Aluminum powder – explosive dust formation possible Water reactive – producing hydrogen gas Bomb Squad on scene with HazMat Challenge: How to handle and dispose of Aluminum powder

RESOLUTION

 To avoid dust formation – need to stabilize the powder      To stabilize, choice between water, cooking oil Leave as is Best option (for recycling purposes): leave as is Actual option used – mixed with water Powder did not react with water because a.

b.

micron size not small enough most likely, already oxidized

ANHYDROUS AMMONIA RELEASE

     Release happened at ice plant, left overnight Brine water saturated with ammonia Middle school yards away from plant Melting ice also contaminated Melting ice and brine water acted as source of ammonia vapor

RESOLUTION

 Plant was closed as airtight as possible  Only one roll-off door was opened  Industrial blower used to vent  Vapors captured using water curtain  Runoff collected for possible sewer disposal  Ice removed as contaminated industrial

waste

SPONTANEOUS COMBUSTION

  Ambient temperature reached over 100 O F  Fire at SFD in a roll off bin of trash SFD being remodeled with paints and stains  Waste paints and rags scattered about

RESOLUTION

     Trash sorted No source of ignition found – cigarette butts, flares, matches, etc.

Rags contaminated with wood stains found in the bin, partly burnt Contractor and Homeowner cautioned about spontaneous combustion Slow oxidation of organic stains on a molecular level gave off heat, enough to ignite combustible materials nearby

Spontaneous Human Combustion?

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Any other questions?