Hazardous Materials

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CHAPTER 9 • \ i

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Courtesy of Tyro Fire Protection Products, Lansdale, Pennsylvania.

air-reactive substance (pyrophoric substance), p. 309 alloy, p. 313 aluminum alkyl, p. 324 amalgam, p. 313 chlorosilane, p. 334 combustible metal, p. 316 dangerous-when-wet material, p. 310 ductile, p. 321

Chemistry of So me Water- and Air-Reactive Substances

flammable solid, p. 310 galvanize, p. 323 hydrolysis, p. 309 ionic hydride, p. 328 malleable, p. 320 metal fume fever, p. 318 metallic carbide, p. 331 metallic phosphide, p. 330 metallic superoxide (metallic hyperoxide), p. 314

silane, p. 334 spontaneously combustible material, p. 310 thermite, p. 321 thermite reaction, p. 321 water-reactive substance, p. 309 Ziegler-Natta catalyst, p. 325

Associate the physical and health hazards of the water- and air-reactive materials noted in this chapter with the information provided by their hazard diamonds and GHS pictograms. Identify the industries that use the water- and air-reactive materials noted in this chapter. Identify the labels, markings, and placards that DOT requires on packaging of water- and air-reactive materials and the transport vehicles used for their shipment. Identify the response actions to be executed when water- and air-reactive materials are released from their packaging into the environment.

308

rhe members of several classes of substances are likely to pose special problems w.he~ they are_ encou?tered by eme_rgency responders. Two such classes are water-reacuve and a1r-react1ve (pyrophonc) substances. • A water-reactive substance is an element or compound that reacts with water to

produce either flammable gases that ignite spontaneously or toxic or corrosive com- pounds chat ?1ay endanger one's health upon exposure. '

• An air-reactive substance (pyrophoric substance) is an element or compound that ignites spont~neousl~ upon _exposure to the oxygen or moisture in the ambient air, rypically posmg the nsk of fire and explosion.

When a substa?ce is water- or air-reactive, the use of water as a fire extinguisher is not only inappropriate, but could be dangerous. Fires involving these substances usually must be fought using special fire extinguishers, not water. As we progress through this chapter, these special extinguishers will be noted.

9.1 WATER- AND AIR-REACTIVE SUBSTANCES When water reacts with another substance, the chemical phenomenon is called hydrolysis. In chemistry, this process is represented by the following general equation:

A + H20(l) -----+ C + D Here, A represents a water-reactive substance, and C and D are the substances produced when A reacts with water. Exposure to the hydrolysis products can be harmful, because C and D may be flammable, corrosive, or toxic. The application of water should always be avoided during emergency response actions at which A is present, especially when either C or D is a flammable or toxic substance.

Consider the metals displayed in Figure 9.1. They react with water, including atmos- pheric moisture, to produce flammable hydrogen; others are so chemically reactive that they spontaneously ignite in air without exposure to an ignition source. As the hydrogen forms, it absorbs the heat of reaction, self-ignites, and triggers the combustion of the met- als. These metals constitute the fuels of class D fires.

As noted, the hydrolysis of a substance may result in the formation of a solution that is corrosive. For example, ferric chloride reacts with water to produce ferric hydroxide and hydrochloric acid.

FeCl3(aq) + 3Hz0(/) -----+ Fe(OH)}(s) + 3HCl( aq) Ferric chloride Water Ferric hydroxide Hydrochloric acid

1A 2A 3A 4A 5A

4 5 6 7

Be B C N

12 13 14 15

Mg 68 78 18 28 Al Si p

3B 48 58

20 21 22 23 24 25 26 27 28 29 30 31 32 33

Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As

38 39 40 41 42 43 44 45 46 47 48 49 50 51

Sr V Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb

water-reactive substance A substance that, by its chemical reaction with water, is likely to become spon- taneously flammable, emit flammable or toxic gases, or generate suf- ficient heat to self- ignite or cause the ignition of nearby com- bustible materials

air-reactive substance (pyrophoric substance)

A substance that ignites spontaneously upon exposure to the air

hydrolysis • The chemi- cal reaction between a substance and water

Ferric chloride

6A 7A BA

8 9 10

0 F Ne

16 17 18

s Cl Ar 34 35 36 Se Br Kr

52 53 54 Te I Xe

FIGURE 9. 1 The symbols of the metals whose background shading are blue and yellow, respectively, represent the alkali metals and combus- tible metals noted in this chapter. Their finely divided physical forms may self-ignite upon exposure to air.

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 309

dangerous-when-wet material For purposes of DOT regulations, a material that by inter- action with water is likely to become spon- taneously flammable or to release a flammable or toxic gas or vapor at a rate greater than 28 in. 3/lb (1 L/kg) per hour when subjected to prescribed test procedures

spontaneously combus- tible material For pur- poses of DOT regulations, either a pyrophoric material or a self-heating material

flammable solid For purposes of DOT regu- lations, any of the fol- lowing types of materials: wetted explosives; thermally unstable compounds that can undergo a strongly exothermic decomposition even without the participa- tion of atmospheric oxygen; and readily combustible solids

Ferric hydroxide is insoluble; hence, the character of the solution is pr . acid. For this reason, aqueous solutions of ferric chloride are corrosive. R~vi~ed by th volumes of the_m are tr~nsported in tank truc~s to ~a.cili~ies that treat water a:tely lar; ter. DOT reqmres earners to display the UN 1dent1ficat10n number 2582 on Wast~ I oran L es, across the center of CORROSIVE placards, or on white square-on-point di ge Pan.

posed on each side and each end of the trucks . alllo% When the hydrolysis of a substance produces a toxic vapor, emergency respo d

to be especially cautious to avoid inhaling it. Some dangerous-when-wet substan n ers need sufficient toxic vapor when they undergo hydrolysis that they pose an inhalatio:~s Prodllce to individuals who are located 0.3 to 6.0 miles (0.5-10 km) downwind. A list of t~althrisk stances is provided in DOT's Emergency Response Guidebook, and several repr ese 8Ub. dangerous-when-wet materials are reproduced in Table 9.1. When these substesentative involved in emergencies, first-on-the scene responders should give special attentio:~ces are and select appropriate actions to reduce or eliminate the potential for their inhalatio O thein

n. 9 .1-A IDENTIFYING AIR-REACTIVE (PYROPHORIC) SUBSTANCES Pyrophoric substances pose the risk of fire and explosion because they ignite rapidly wh exposed to at~osphe_ric oxygen. This inherent hazard may be initiated ':"hen they react wi:~ the atmospheric moisture encountered as they are released from their containers. l'h su~stances not only burn spontaneously, but their fires are so exothermic that they pos:se umque challenge to firefighting efforts. To prevent their premature ignition, pyrophort su_bs~ances sometimes are stored and processed under oil or other nonaqueous liquids

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within enclosed, oxygen-free, dry atmospheres. To avoid their premature ignition during storage and transportation, manufacturers seal them hermetically in airtight containers.

Fortunately, few pyrophoric substances are used as commercial chemical products and they are almost always stored in nonbulk amounts. OSHA requires their manufactur'. ' ers, distributors, and importers to post the GHS flame pictogram on the labels of pyro- phoric liquids or solids, and the flame and explosive pictograms on t_he labels of substances or mixtures that form flammable gases upon contact with water.

9.1-B TRANSPORTING WATER-REACTIVE SUBSTANCES When water-reactive substances are transported, DOT regulates their transportation as dangerous-when-wet materials, spontaneously combustible materials, flammable solids, or corrosive materials. Individual water-reactive substances may be members of one or more of these hazard classes. DOT requires their shippers and carriers to comply with relevant labeling, marking, and placarding requirements.

SOLVED EXERCISE 9.1

310

What information regarding water reactivity is immediately conveyed to responding firefighters by a hazard dia- mond displayed on the exterior wall of a burning shed? Solution: Information regarding the water reactivity of a substance is conveyed on a hazard diamond in two ways . As first noted in Section 1. 11 , a substance 's relative degree of the health, fire, and instability hazards 15 conveyed through numbers in the three topmost quadrants of a diamond . The relative degree of water reactivity is conveyed by the number that appears in the rightmost yellow quadrant, as follows :

"3" means that the substance reacts explosively with water. "2" means that the substance may react violently with water or may form potentially explosive mixtures with water. "1" means that the substance may react with water with some release of energy, but not violently. "O" means that the substance does not react with water.

In addition, the prese_nce o'. a ~apital letter W with a line through i~s center ry,,J) in t~e bottommo~t qua~~:~t of the diamond serves to signal f1ref1ghters that they should avoid applying water when f1ght1ng a fire in the d

Responding firefighters use this combination of information to select an action appropriate to the incident at han ·

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

TABLE 9.1 Some Classes of Water-Reactive Substancesa CLASS OF SUBSTANCE EXAMPLE

CHEMICAL FORMULA HAZARDOUS HYDROLYSIS PRODUCT Acetyl halides

0 Acet yl bromide // Hydrogen bromide CH3- C

\ Br 0

Acetyl chloride // Hydrogen chloride CH3-C

\ Cl

Acids Fluorosulfonic acid F- 502-0H Hydrogen fluoride Nitrosylsulfuric acid

O=N- 0 - 50 2-0-H Nitrogen dioxide (h lorosilanes Methyldichlorosilane

CH3-Si- Cl2H Hydrogen chloride Methyltrichlorosilane CH3-Si- Cl3 Hydrogen chloride Trichlorosilane Cl3Si H Hydrogen chloride

Metallic amides Lithium amide Li NH2 Ammonia Magnesium diamide Mg(NH2h Ammonia

Metall ic halides Aluminum bromide, AIBr3 Hydrogen bromide anhydrous Aluminum chloride, anhydrous AICl3 Hydrogen chloride

Antimony pentafluoride, anhydrous SbFs Hydrogen fluoride

Metallic hypochlorites Calcium hypochlorite Ca(CI Oh Chlorine, hydrogen chloride Lithium hypochlorite LiCIO Chlorine, hydrogen chloride

Metallic nitrides Lithium nitride Li 3N Ammon ia Metallic oxychlorides Chromium oxychloride Cr(OClh Hydrogen chloride Metallic phosphides Aluminum phosphide AIP Phosphine

Calcium phosphide Ca3P2 Phosphine Magnesium aluminum Mg3P2 · AIP Phosphine phosphide Magnesium phosphide Mg3P2 Phosphine Potassium phosphide K3P Phosphine Sodium phosphide Na3P Phosphine Zinc phosph ide Zn 3P2 Phosph ine

Nonmetallic halides Iodine pentafluoride IFs Hydrogen fluoride Phosphorus pentachloride PCls Hydrogen chloride Silicon tetrachloride SiCl4 Hydrogen chloride Thionyl chloride SOC l2 Hydrogen chloride, sulfur dioxide

Sulfides Ammonium hyarosulfide NH4HS Hydrogen sulfide, ammonia Ammonium sulfide (N H4)iS Hydrogen sulfide, ammonia -

Others Chlorine dioxide (hydrate)b CI02 Chlorine Uran ium hexafluoride UF6 Hydrogen fluoride •

Adapted in part from Table 2, Emergency Response Guidebook (Washington, DC. U.S . Department of Transportation, 2012). bsection 11 .8.

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 311

Lithium metal

TABLE 9.2 Physical Properties of the Alkali Metals

LITHIUM SODIUM POTAss,u~ Melting point 354°F (179°C) 2os°F (9s 0 c) 147°F (54,C) Boiling point 2437°F (1337°C) 1618°F (881°C) 1425°F (774, Specific gravity at 68°F (20°C) 0.53 0.97

C) 0.86

Autoignition point 352°F (178°C) 2so°F (121°c)

9.2 ALKALI METALS We consider the properties of three alkali metals in this section: lithium, sodium potassium. The properties of these three metals illustrate the uniqueness of their reac~i~nd Some of their physical properties are noted in Table 9.2. ns.

The alkali metals spontaneously ignite. Furthermore, they displace hydrogen fro water as the following equations illustrate: tn

2Li(s) + 2H20(/) 2Li0H(aq) + Hz(g) Lithium Water Lithium hydroxide Hydrogen

2Na(s) + 2H20(l) 2NaOH(aq) + Hz(g) Sodium Water Sodium hydroxide Hydrogen

2K(s) + 2H20(l) 2KOH(aq) + Hz(g) Potassium Water Potassium hydroxide Hydrogen

When metallic lithium reacts with water, the hydrogen produced does not immediately ignite; but when metallic sodium and potassium react with water, the hydrogen bursts spontaneously into flame as it is produced.

Chemical manufacturers display the GHS flame pictogram on labels affixed to con- tainers holding the alkali metals.

9 .2-A METALLIC LITHIUM Lithium is a soft, silvery metal and is the least dense solid element at normal conditions. Metallic lithium is so light that pieces of it float even in low-density petroleum products like kerosene and gasoline.

Metallic lithium and lithium compounds are valuable raw materials used to manufac- ture porcelain, ceramics, castings, batteries, zero-expansion glass, fungicides, bleaching agents, pharmaceuticals, and greases. In contemporary times, they have become increas- ingly popular within the chemical industry as raw materials used to synthesize organic compounds. Metallic lithium itself is a component of a lightweight magnesium alloy.

There are two types of lithium batteries, called primary and secondary lithium batter- ies. Both types pose the risk of fire. They differ as 'follows:

Primary lithium-metal batteries. These are disposable, non-rechargeable batteries. Although they have variable compositions, the most common primary lithium batte~y uses metallic lithium and manganese dioxide as its electrodes, and lithium perchlorate dis· solved in propylene carbonate and dimethoxyethane as the electrolyte. Primary lithium· metal batteries are encountered mainly in the coin or button cells used in watches and digital cameras. Upon contact with water, they produce hydrogen. .

Secondary lithium-ion batteries. These are rechargeable batteries, also havi~g variable compositions. A typical type uses a lithium alloy as the positive plate, graphi~e as the negative plate, and lithium hexafluorophosphate (LiPF6 ) dissolved in an organic

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

C as the electrolyte. Exampl f h . • b d 0Jven es o t e orgaruc solvents are diethyl car onate an s I e carbonate. Secondary lith' · b . . 11 ethY en _ium-ion attenes are used m laptop computers, ce hones, powe~ t~ols, _a nd all-el~ctnc automobiles. When damaged, the liquid electrolyte

fn secondary hthmm-ion batteries may ignite. Both p~imary and secondary lithium batteries may short-circuit and ignite when they

have been u_nproperly packaged ?r damaged. Sufficient heat is generated to cause fire when they discharge sudden!! durmg short-circuiting. They are also potentially hazardous because the_ ~Jectrolytes used m them may ignite when exposed to the heat generated during short-circw~m~. .

When hthmm me~a1. reacts wuh water, the hydrogen is slowly displaced from the water. The h!drogen dissipates into the surrounding environment without ever achieving a concentrat_wn equ~l to 0 _r greater than 4% by volume, its lower flammable limit.

During its reaction with water, metallic lithium remains in the solid state of matter. Although the heat of the reaction initially is absorbed by the metal, it is transmitted to the surrounding wat~r, the _metal's temperature remains below the boiling point of water.

When metallic hthmm is left exposed to the air at room conditions, it does not spon- taneously ignite. Although the metal oxidizes in the air it does so very slowly. Even mol- ten lithium oxidizes so slowly that it can be poured from a container in the open air without losing its bright luster.

In an atmosphere of absolutely dry air, lithium metal does not spontaneously burn. When exposed to an ignition source, however, the metal burns in the air with a character- istic crimson color, forrning a mixture of lithium oxide and lithium nitride.

4Li(s) + Oz(g) 2Li20(s) Lithium Oxygen Lithium oxide

6Li(s) + Nz(g) 2Li3N(s) Lithium Nitrogen Lithium nitli de

9.2-B METALLIC SODIUM Like metallic lithium, sodium also is a soft, silvery bright metal. It is the most commonly encountered alkali metal and the only one produced in bulk. Sodium metal generally is available for commercial use in the form of solid bricks.

The majority of the metallic sodium produced in the United States formerly was used as a raw material for the manufacture of the vehicular fuel additives tetraethyllead and tetramethyllead. This use of metallic sodium was sharply curtailed in 1975, when EPA banned the use of leaded gasoline in vehicular fuels. Today, metallic sodium is used pri- marily as a raw material for the production of highly reactive sodium compounds such as sodium peroxide and sodium hydride. In addition, metallic sodium is used as a catalyst during the production of certain types of synthetic rubber.

Metallic sodium sometimes is encountered commercially in alloys such as sodium/ potassium alloys, sodium/lead alloys, and sodium amalgams. An alloy is a solid mixture of two or more elements, none of which can be separated by mechanical means. An amalgam is a special alloy in which one of these elements is elemental mercury. When a sodium alloy or amalgam is used instead of sodium alone, sodium reacts less vigorously. Consequently, chemical manufacturers often use sodium alloys and amalgams when the rate of a reaction requires careful control; notwithstanding this fact, the use of all amal- gams has lost its popularity owing to the toxicity of mercury.

Metallic sodium reacts rapidly with water. In fact, the reaction occurs so rapidly that the hydrogen produced is unable to dissipate before it ignites. Instead, it concentrates in the immediate vicinity of the metal, where, induced by the heat of reaction, it self-ignites and spontaneously burns. The metallic sodium absorbs the heat .of reaction and melts, thereby exposing an underlying surface of the solid metal for further reaction.

Sodium metal

A solid mixture of two or more mechanically inseparable elements

amalgam An alloy of mercury with one or more elements

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 313

Potassium metal

metallic superoxide (metallic hyperoxide)

An inorganic compound composed of metallic and superoxide ions

Unlike lithium, metallic sodium does not react with atmospheric nitrog sod~um burns in an atmosphere of oxygen, producing a mixture of sodiu~: ~eta.Ilic sodmm peroxide. Xide and

4Na(s) + 02(g) --+ 2Na20(s) Sodium Oxygen Sodium oxide

2Na(s) + 02(g) --+ Na202(s) Sodium Oxygen Sodi um peroxide

Because sodium peroxide is a powerful oxidizer (Section 11.16-A), it itself is ah material. azardaus

Although bulk sodium is not pyrophoric, nonbulk pieces of metallic sodiu . spontaneously at room temperature with a characteristic yellow flame . In absol 111 :gnite air, however, this oxidation does not occur at an appreciable rate, which suggest~~~ Y dry oxidation of metallic sodium in air is triggered by the reaction of metallic sod· at the

h . . 1 f . . . d' tum and atmosp enc water vapor. To reduce its potentia or Igmtton, so mm generally is st under kerosene. 0red

9.2-C METALLIC POTASSIUM Potassium is a soft, silvery metal. Although it formerly was used with sodium as a he exchanger fluid in nuclear reactors, metallic potassium now has so few commercial u at. h . . t at It IS rarely encountered.

The combustion of potassium metal in air is associated with the production of a cha _ acteristic purple flame. The combustion product is primarily potassium oxide. r

4K(s) + 02(g) --+ 2K20(s) Potassium Oxygen Potassium oxide

When potassium burns in an atmosphere of pure oxygen, however, a mixture of potassium oxide, potassium peroxide, and potassium superoxide is produced.

2K(s) + 02(g) --+ K202(s) Potassium Oxygen Potassium peroxide

K(s) + 02(g) --+ K02(s) Potassium Oxygen Potassium superoxide

A superoxide, more properly called a hyperoxide, is a compound containing the superoxide ion, whose chemical formula is 0 2. Metallic superoxides (metallic hyperoxides} are extraordinarily reactive oxidizing agents (Section 11.16-B).

Metallic potassium reacts with water even more rapidly than does sodium. The vigorous nature of this reaction most likely is due to the presence of minute amounts of potassium superoxide produced when potassium oxidizes. The hydrogen produced by the reaction of potassium and water initially concentrates around the metal, where it self-ignites; then,_ the heat of reaction triggers the burning of the potassium metal. The reaction between potassium superoxide and atmospheric moisture occurs with such ease that it has been employed com· mercially as a means of supplying oxygen in self-contained breathing apparatus.

9 .2-D TRANSPORTING ALKALI METALS AND PRIMARY LITHIUM BATTERIES

When shippers offer an alkali metal or its alloys, amalgams, or dispersions for transpo~a- tion, DOT requires them to identify the appropriate material on the accompanying shiP~0f paper. The shipping descriptions of some representative examples are listed in Table . · · DOT also requires shippers and carriers to comply with all applicable labeling, rnarklllg, and placarding requirements.

314 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

!(ALI METAL S, AL ERSIONS, ALLOYS, OR PRODUCTS SHIPPING DESCRIPTION 01SP

OR ITS AMALGAM

I' metal alloys (liquid) Alka 1 UN1421, Alkali metal alloy, liquid, n.o.s., 4.3, PG I

(Dangerous When Wet)

Alkali metal dispersions UN1391, Alkali metal dispersion, flammable, 4.3, PG I (Dangerous When Wet)

Alkaline earth metal alloys UN1393, Alkaline earth metal alloy, n.o.s., 4.3, PG II

Lithium UN1415, Lithium, 4.3, PG I (Dangerous When Wet)

Primary lithium metal battery UN3090, Lithium battery, 9, PG II (Dangerous When Wet)

Primary lithium metal batteries, contained UN3091, Lithium battery, contained in equipment, 9, in equipment PG II (Dangerous When Wet)

Primary lithium metal batteries, packed UN3091, Lithium battery, packed with equipment, 9, with equipment PG II (Dangerous When Wet) - potassium UN2257, Potassium, 4.3, PG I (Dangerous When Wet) - Sodium UN1428, Sodium, 4.3, PG I (Dangerous Whe nWet

The transportation of primary lithium batteries is subject to additional regulations published at 49 C.F.R. §173.185. DOT requires manufacturers, shippers, and carriers to implement certain safety precautions when offering lithium-metal batteries for transpor- tation. For example, shippers must package individual lithium-metal batteries in an inner packaging, separated by a divider and surrounded by noncombustible, nonconductive cushioning that prevents contact of the battery terminals with other batteries, metal objects, or conductive surfaces. Strong outer packaging or containment that complies with Packing-Group-II performance standards also is required.

When transporting primary lithium batteries domestically, DOT requires shippers to include the following statement on the shipping paper:

This shipment contains primary lithium batteries. Do not damage or mishandle the packages. If the package is damaged, flammability hazard may exist; batteries must be quarantined, inspected, and repacked.

When shippers intend to transport lithium-metal batteries by aircraft, DOT also requires them at 49 C.F.R. §172.102.188 to affix the lithium-battery-handling label shown in Figure 9.2 on two opposing sides or ends {other than the bottom) of the packag- ing, and to provide either of the following markings on its surface:

PRIMARY LITHIUM BATTERIES - FORBIDDEN FOR TRANSPORT

ABOARD PASSENGER AIRCRAFT

LITHIUM METAL BATTERIES - FORBIDDEN FOR TRANSPORT

ABOARD PASSENGER AIRCRAFT

When shippers intend to transport lithium-metal batteries by cargo aircraft, DOT also requires the CLASS 9 and CARGO AIRCRAFT ONLY labels shown in Figures 6.5 and 6.6,

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 315

TABLE 9.3 Shipping Descriptions of Some Representative Alkali Metals, Their Amalgams, Dispersions, Alloys, and Products

ALKALI METAL OR ITS AMALGAMS, DISPERSIONS, ALLOYS, OR PRODUCTS SHIPPING DESCRIPTION Alkali metal alloys (liquid) UN1421, Alkali metal alloy, liquid, n.o.s., 4.3, PG I

(Dangerous When Wet) Alkali metal dispersions UN1391, Alkali metal dispersion, flammable, 4.3, PG I

(Dangerous When Wet) - Alkaline earth metal alloys UN1393, Alkaline earth metal alloy, n.o.s., 4.3, PG II Lithium UN1415, Lithium, 4.3, PG I (Dangerous When Wet) Primary lithium metal battery UN3090, Lithium battery, 9, PG II (Dangerous When Wet) Primary lithium metal batteries, contained UN3091, Lithium battery, contained in equipment, 9, in equipment PG II (Dangerous When Wet) Primary lithium metal batteries, packed UN3091, Lithium battery, packed with equipment, 9, with equipment PG II (Dangerous When Wet)

Potassium UN2257, Potassium, 4.3, PG I (Dangerous When Wet)

Sod ium UN1428 S , odium, 4.3, PG I (Dangerous When Wet)

When transporting primary lithium batteries domestically, DOT requires shippers to include the following statement on the shipping paper:

When shippers intend to transport lithium-metal batteries by aircraft, DOT also requires them at 49 C.F.R. §172.102.188 to affix the lithium-battery-handling label shown in Figure 9.2 on two opposing sides or ends (other than the bottom) of the packag- ing, and to provide either of the following markings on its surface:

PRIMARY LITHIUM BATTERIES - FORBIDDEN FOR TRANSPORT

ABOARD PASSENGER AIRCRAFT

LITHIUM METAL BATTERIES - FORBIDDEN FOR TRANSPORT

ABOARD PASSENGER AIRCRAFT

When shippers intend to transport lithium-metal batteries by cargo aircraft, DOT also requires the CLASS 9 and CARGO AIRCRAFT ONLY labels shown in Figures 6.5 and 6.6,

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 315

FIGURE 9.2 When pack- ages of lithium-metal bat- teries are transported by cargo aircraft, DOT requires shippers to affix this lithium-battery han- dling label on opposing sides of each package adjacent to a CLASS 9 and a CARGO AIRCRAFT ONLY label. The printing on the lithium-battery- handling label is black with a red-hatching bor- der on a contrasting background.

combustible Any metal

whose distinct particles or pieces, regardless of size or shape, can read- · ily ignite to produce an NFPA class D fire

~,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,~ s s

CAUTION! Lithium Metal Battery

II A ! 111 ,= DO NOT LOAD OR TRANSPORT

PACKAGE IF DAMAGED For Emergency information, call CHEMTREC:

S 1-800-424-9300 - North America S 1-703-527-3887 - International

For product information, call 315-332-7100

~'''''''''''''''''''''''''''''''''''''''''"'

respectively, to be affixed adjacent to each other on two opposing sides or ends (other th the bottom) of the packaging. DOT also regulates the nature of the packaging to reduce t~n likelihood of short circuiting and damage to battery terminals. e

The Federal Aviation Administration does not permit large palletized shipments of primary lithium batteries on cargo or passenger aircraft. Furthermore, although DOT permits the transportation of primary lithium batteries contained in electronic equipment it does not permit air transport of loose lithium batteries in checked baggage. '

9.3 COMBUSTIBLE METALS Magnesium, titanium, zirconium, aluminum, and zinc possess a common hazardous fea- ture. Although bulk pieces of these metals typically are difficult to ignite, their finely divided forms may self-ignite in air without exposure to an ignition source. They are examples of combustible metals, some of which are also pyrophoric at elevated tempera- tures. These metals represent the fuels of class D fires. Some of their relevant physical properties are provided in Table 9.4.

Chemical manufacturers display the GHS flame pictogram on labels affixed to con- tainers holding hazardous forms of the combustible metals.

The finely divided forms of some combustible metals are regarded as water- and air- reactive substances to varying degrees. They include dusts, powders, chips, turnings, flakes, punchings, borings, ribbons, and shavings. These forms are commonly produced during metal-forging and metal-machining operations. Often, the heat retained from these processes is sufficient to cause the metals to spontaneously ignite. The finely divided forms of metals generated during machining, grinding, boring, and other fabrication processes are also likely to be coated with the cutting oils used as lubricants, which can ignite as the primary fuel. .

The finely divided forms of combustible metals react with water to produce hy~o- gen. The spontaneous ignition of the hydrogen kindles the burning of the underlying metal. The rate of hydrogen production is affected by a number of factors including the particle size, distribution and dispersion, purity, and ignition temperature of the metal, as well as the moisture content of the surrounding atmosphere. Some relevant physical prop· erties of these metals are provided in Table 9.4.

316 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

TABLE 9.4 Physical Properties of Several Combustible Metals

MAGNESIUM ZIRCONIUM

Melting point , 200°F (649°C) 3326°F (1830°()

soiling point 2012°F (11 oo•q 7911 °F (4377°C) 'fc gravity at 68°F (20°() 1.74 6.49 speCI I

,Autoignition point 883°F (472. 18°c) 662°F (3S0°C) (powder) (powder) 9S0°F (s10°c) (ribbons and shavings) 1202°F (6so 0 c) (massive chunks)

ALUMINUM ZINC

Melting point 1220°F (660°c) 786°F (419°C)

soiling point 4221 °F (2327°C) 1665°F (907°C)

Specific gravity at 68°F (20°() 2.70 7.14

Autoignition point 1400°F (760°() 860°F (460°c) ( owder owder p (p

9.3-A METALLIC MAGNESIUM As previously noted in Table 4.1, magnesium occurs to the extent of 1.9% by mass on Earth's surface, where it typically is found in such ores as magnesite, dolomite, soapstone, and brucite. Magnesium is also found extensively in underground brines, mainly as magnesium chloride. It is also present in seawater as magnesium chloride and magnesium sulfate.

Magnesium metal is produced mainly for commercial use by the electrolysis of a mol- ten mixture of anhydrous magnesium chloride and potassium chloride.

MgClz(/) Mg(/) + Clz(g) Magnesium chloride Magnes ium Chl01ine

The potassium chloride increases the conductivity of the salt mixture and reduces its melt- ing point. At the temperature of the electrolytic cell, molten magnesium floats on the salt mixture and is periodically removed through a trough and poured into molds.

Magnesium is an exceptionally lightweight metal. It therefore is often employed in the construction of aircraft, racing cars, transportable machinery, engine parts, automo- bile frames and bumpers, wheel rims, and other items for which the mass of the object is pertinent. Because of its popularity, magnesium is commercially available in a variety of sizes ranging from a dust or powder to massive ingots.

As illustrated by the following examples, magnesium is a very reactive metal:

1 Although it reacts slowly with cold water, magnesium reacts rapidly with warm and hot water, producing hydrogen.

Mg(s) + 2H2O(l) Mg(OH)z(s) + Hz(g) Magnesiu m Water Magnesium hydroxide Hydrogen

1 Metallic magnesium is also a strong reducing agent. This property is put to use in the metal manufacturing industry, where molten metallic magnesium is used to reduce the metals in certain ores such as those containing titanium and zirconium com- pounds. Magnesium powder is also used as a reducing agent in many fireworks in which its reactions contribute to the production of brilliant displays of light. '

TITANIUM 3034°F (1668°()

5948°F (3260°()

4.51 482°F (2so 0 0 (3. 175-mm-thick plate); >2192°F (>1200°C) (6.35-mm-diameter rod)

Magnesium metal turnings

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 317

metal fume fever The occupational disease associated with inhal- ing metal fumes and dusts, especially of magnesium and zinc

Titanium metal powder

1 The most well-known chemical property of magnesium metal is its comb ; emental magnesium burns, approximately 75% combines with atmosphe ~stibility A orm magnesium oxide . rte oicyge~ ·11

tG 2Mg (s) + 0 2(g) 2Mg0(s)

Magnesium Oxyge n Magnesium oxide

The remaining 25% combines with atmospheric nitrogen to form magnesium .. llttr1de

3Mg(s) + N2(g) Mg3N 2(s) . Magnesium Nitrogen Magnesiu m nit1i de

~agnesium ribbon once was used in one-time-use photo flashbulbs to illum· with a brilliant flash of light. Inate scenes

The burning of bulk pieces of magnesium is hazardous. When raised to ate of 1200°F (649°_C), massive_ingots, casting~, and ot~e_r bulk ~on!1s of metallic rn~P~ra~ure me~t and burn v~go~ously with the producu_o~ ?f bnll1~nt, blmdmg white flam.es. t est~lll as it flows, the hqmd metal drops from its m1t1al locat10n to lower levels where . ~ntng

b 'b ' 1t 1g · com ust1 le materials encountered in its pathway. ll!tes . ln~ividuals exposed to magnesium fumes are at risk of contracting metal furne f

This disease is characterized by a rise in body temperature, cough, sore throat, chest ~Ver. ness, headache, fever, metallic taste, nausea, vomiting, and blurred vision. tight-

9 .3-8 METALLIC TITANIUM As noted in Table 4 .1, titanium occurs on Earth's surface to the extent of 0.58% by mas The element occurs primarily as titanium(IV) oxide . One such ore, rutile, is abundant t' beach sands in Australia, South Africa, and Sri Lanka. n

The titanium manufacturing process consists of the following two steps:

First, rutile or a similar ore is reacted with chlorine and carbon at approximately 1112 °F ( 600°C) to produce titanium(IV) chloride.

Ti02(s) + 2C(s) + 2Cl2(g) TiCl4(g) + 2CO (g) Titanium(IV) oxide Carbon Chlorine Titan ium(IV) chloride Carbon monoxide

Then, titanium(IV) chloride is reacted with molten magnesium within a steel vessel under an atmosphere of an inert gas like helium or argon at approximately 1472°F (800°C).

TiCl4(g) + 2Mg (/) Ti (s) + 2MgC12(s) Titanium(IV) chloride Magnesium Titanium Magnesium chl oride

The magnesium chloride formed as a by-product is leached from the reaction mix· ture, leaving the basic form of the metal known as titanium sponge, so called because its physical appearance resembles the shape of a sponge. ·

These production steps are costly, which currently hinders the widespread use of titanium, Although it is 45% lighter in mass than steel, metallic titanium is just as strong as

steel. Because titanium possesses this combination of lightness and strength, it often 1~ alloyed with aluminum and vanadium, which then is used to manufacture air~~aft an r automotive p_arts,_ jet eng~nes, and_ miss~les. In mo~ern-~ay commerc~al and milit::i/:s aircraft, titaruum 1s replacmg alumm1,1m m blades, discs, rmgs, and engme cases, as bulkheads, tail sections, landing gear, wing supports, and fasteners. . and

In the automotive industry, titanium metal now is used in several consumer car·ngs motorcycle applications. It is used primarily for exhaust systems, suspension spri ' engine valves, connecting rods, and turbocharger compressor wheels.

318 Chapter g Chemistry of Some Water- and Air-Reactive Substances

atlic titanium is also found in everyday items such as jewelry, skis, and golf _M;:nr. Titanium prostheses often are selected by orthopedic surgeons for hip and

eqU1P lacements . kne~;:nium m_etal h~s a great a_ffinity for oxygen. Once exposed to air, a thin layer of

. n(IV) oxide quickly deposits on the surface of the metal and protects the underly- tifl1111~al from further chemical attack. Then, the metal is highly resistant to corrosion by ing uie 'ds chlorine, oxidizing agents, and seawater.

osr ac1 ' f . . h . . . 111 The resistance o tlta~mm to c em1cal attack has been put to good use m various •ocluding the followmg:

1113)'5, I

1 Because it is lightweight and resistant to corrosion by seawater, metall_ic tita~ium is used in the stru~ture of underwater machinery. Most likely, its corros10n resistance was an influencmg factor that prompted Russia in 2007 to mount a flag made from riranium on the ocean floor at the North Pole from a deep-submergence vehicle.

1 Because metallic titanium is resistant to corrosion by seawater, the U.S. Office of Naval Research ordered its first ship hull constructed entirely from it in 2012.

1 Because it is resistant to corrosion by most acids and chlorine, metallic titanium is also used in the construction of vessels in which these raw materials will be stored, transported, or reacted. One notable exception to this general observation, however, is hydrofluoric acid, which reacts with metallic titanium.

Although the bulk forms of titanium are not considered hazardous, Table 9.4 shows that titanium has the lowest auto-ignition point of the combustible metals. Finely divided titanium poses a dangerous risk of fire and explosion. It is generated when fabrication operations are conducted on titanium and its pieces are cut, formed, and welded.

When metallic titanium burns in air, a mixture of titanium(IV) oxide and titanium(III) nitride is produced.

Titanium Oxygen Titanium(IV) oxide

2Ti(s) + N2(g) - 2TiN(s) . Titanium Nitrogen Titanium(lll) nitride

The reactions may be initiated by the combustion of the hydrogen produced when the finely divided metal reacts with atmospheric moisture.

Ti(s) + 2H20(g) - Ti02(s) + 2H2(g) Titanium Water Titanium(lV) ox ide Hydrogen

9.3-C METALLIC ZIRCONIUM Metallic zirconium is produced primarily from zirconia, a naturally occurring ore con- taining zirconium(IV) oxide (ZrO 2 ), by the method just described for production of tita- nium. Today, the metal is used almost exclusively in the nuclear and steel industries. In the nuclear industry, tubes made of a zirconium alloy are used to hold the uranium(IV) oxide pellets needed as fuel for use in reactor cores (Section 16.9-C), and in the steel industry, zirconium is used to remove oxygen from molten steel. Zirconium dust formerly was used as the active component of specialized camera photoflash bulbs, and it has also been used militarily as an incendiary agent. · -

Zirconium dust constitutes a risk of fire and explosion. When it is transferred from one container to another, the dust particles absorb the heat generated by friction as the Particles move against one another. When these particles are hot, as when they are first Produced, the temperature of the dust can exceed its autoignition point, whereupon it spontaneously ignites.

Zirconium metal powder/dust

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 319

Aluminum metal powder/dust

malleable The prop- erty or capability of being rolled or ham- mered into shapes

The ease of ignition of zirconium dust is associated with its former use as~ diary agent in a shotgun round known as Dragon's Breath , The round, when inincen. into the magazine of a shotgun, burst into flame when the gun ~as fired and shors?ted the gun's barrel like a flamethrower. Zirconium dust, however, is extremely exp r.oni

. . ·1· f D ens1v Despite its fearsomeness in application, the routme mi itary use O ragon's Breath~- cost-prohibitive. . . . is

When zirconium dust burns in air, the resultmg fire provides an exceedingly b il]j· d . f . f . r ant white flame. The combustion results in the pro uction o a mixture o zirconium OJ( ,

d · · · 'd 1de an zircoruum rutn e. Zr(s) + Oz(g) Zr02(s)

Zirconium Oxygen Zirconium oxide

2Zr(s) + N z(g) 2ZrN (s) Zirconium Nitrogen Zirconium nitride

The reactions may be initiated by the combustion of hydrogen, produced when the dust reacts with hot atmospheric moisture.

Zr(s) + 2H20(g) Zr02(s) + 2Hz(g) Zirconium Water Zirconium oxide Hydrogen

Water does not react with the zirconium alloy used in nuclear reactors; in fact, under normal operating conditions, it cools their fuel assemblies. When zirconium or its alloy is red-hot, however, the metal decomposes water to form hydrogen. When hydrogen is pro- duced at malfunctioning nuclear reactor sites, it must be vented to the outside environ- ment to prevent the confinement vessel from exploding.

9.3-D METALLIC ALUMINUM Table 4.1 lists aluminum as the most abundant metal on Earth's surface, 7.5% by mass. As the element, aluminum is too reactive to be found in an uncombined form in nature. Instead, it is found in minerals like cryolite and in such materials as clay and feldspar, in which it is combined with silicon and oxygen.

Aluminum metal is produced by the electrolysis of aluminum oxide dissolved in fused cryolite, which serves as the electrolyte.

2Al203(s) 4Al(l) + 30z(g) Alu mi num oxide Aluminum Oxygen

The aluminum metal is denser than molten cryolite; therefore, it collects at the bottom of the electrolytic cell, from which it is tapped and cast into ingots.

Aluminum is an example of a malleable metal; that is, it can be rolled or ham· mered into a relatively thin sheet or foil. Aluminum foil is a popular kitchen item. Firefighters encounter aluminum foil bonded to fabric in aluminized protective suits that are worn when they must approach fires that release exceptionally high levels of radiant heat.

Because it is lightweight and durable, aluminum sheeting is used to produce a wide variety of commercial products including the common soda can. In building construction, aluminum sheeting is used as siding, eaves, screens, and window and door frames. During building fires, these aluminum components can melt and col· lapse, because the temperature attained often exceeds the melting point of aluminum, 1220°F (660°C).

The principal material employed as the metal skin of most standard aircraft is an alu· min_um_ or aluminum alloy sheet!ng. The metal cannot be used as the outer skin of supe~ some aircraft, however, because 1t becomes too hot and softens from the friction generate by the fast movement through the air.

320 Chapter 9 Chemistry of Some Water- and Air-Reactive Substances

Magnesium ribbon

T 10 in.

Pan of dry sand

GURE 9,3 In this laboratory demonstration, a mixture of powdered aluminum and iron(III) oxide is inserted ~~to a cone over a pan of dry sand (wh~ch protects the tabletop from possible damage). A magnesium ribb~n is . rted into the thermite mixture and ignited. The heat of combustion initiates the reaction between aluminum ;; iron(III) oxide. Molten iron spits from the reaction mixture and drips into the sand.

Aluminum is also a ductile substance; that is, it can be drawn into wires. Although aluminum wire is twice as effective as copper wire for conducting electricity, the use of aluminum electrical wiring is undesirable. This is because the heavy deposit of aluminum oxide produced on the surface of aluminum wiring restricts the flow of dectrical current and causes the metal to become overheated. This situation constitutes a fire hazard.

The deposition of aluminum oxide on the surface of aluminum wiring is associated with the extraordinary affinity that aluminum and oxygen have for each other. Aluminum exposed to air is covered with a thin, tenacious coating of aluminum oxide that gives the metal a dull, white luster. Although this oxide coating protects the underlying metal from further oxidation, the coating does not protect the aluminum from other forms of chemi- cal attack. Seawater, for instance, corrodes metallic aluminum.

This chemical affinity of metallic aluminum for oxygen is evident from the chemical reaction noted in Figure 9.3 involving powdered aluminum and iron(III) oxide. The mix- ture of 27% powdered aluminum and 73% iron(III) oxide is commonly called thermite. When the mixture is activated by a magnesium fuse, a reaction producing molten iron and aluminum oxide occurs.

Aluminum Ferric oxide Iron Aluminum oxide

This phenomenon is called the thermite reaction. It releases such considerable heat that temperatures of approximately 3990°F (2199°C) result. Because this temperature is above the melting point of iron [2800°F (1538°C)], it is produced by this chemical reaction as a molten, white-hot liquid. The thermite reaction cannot be stopped with water.

In the days of the old West, the thermite reaction was used to weld rails together during the construction of railroads. During World War II, thermite was used exten- sively as the incendiary agent in bombs, especially against the British during the London Blitz. In contemporary warfare, however, the use of thermite in incendiary ~eapons is essentially banned by Protocol III of the Convention on Certain Conven- tional Weapons (Section 7.3 ). Protocol III limits the use of all incendiary weapons against civilian targets.

ductile The property of metals associated with their capability of being stretched into wires

thermite The mixture of 27% powdered aluminum and 73% iron(lll) oxide

thermite reaction The chemical reaction used in some welding opera- tions and incendiary weapons during which elemental iron is pro- duced by the reduction of iron(III) oxide with elemental aluminum

Chapter 9 Chemistry of Some Water- and Air-Reactive Substances 321