Hazardous Materials

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TABLE 8.12 Shipping Descriptions of Perchloric Acid

fORM Of PERCHLORIC ACID SHIPPING DESCRIPTION hloric acid (contains not more than 50% acid by mass) UN1802, Perchloric acid, 8, (5.1), PG II perc

hloric acid (contains more than 50% acid but not more UN1873, Perchloric acid, 5.1, (8), PG I perc 72 % acid by mass) than

10.c OXIDIZING POTENTIAL OF PERCHLORIC ACID S, d hl . 'd · ,-1 t concentrate perc one aci is a powerful oxidizing acid but when it is diluted with nO, . 'd ' water, perchlor~c ac_i reacts a_s a weak ?xidizing agent even when hot. The hot, _concen-

ated perchlonc acid reacts v10lently with organic compounds including cellulosic mate- ~als such as sawdust. In fact, a mixture of perchloric acid and sawdust ignit~s spontaneously. Every m~asure s~ou~d b~ taken to segregate perchloric acid and orgaruc compounds, because their combmation is regarded as a fire and explosion hazard.

S.10-D TRANSPORTING PERCHLORIC ACID When shippers offer perchloric acid for transportation, DOT requires them to identify it on the accompanying shipping paper in one of the ways shown in Table 8.12, as relevant. All labeling, marking, and placarding requirements apply.

8.11 HYDROFLUORIC ACID Hydrogen fluoride is a colorless, fuming liquid or vapor having the chemical formula HF(/) or HF(g), respectively. Its anhydrous form is typically represented by the acronym AHF. Solutions of hydrogen fluoride in water are denoted by the chemical formula HF(aq ).

Hydrofluoric acid solutions are used for a variety of purposes. In the household, they are found as components of rust removers and aluminum-cleaning products. In the glass industry, they are used to polish, etch, and frost glass. In the metallurgical and steel indus- tries, they are used to pickle brass, copper, and certain steel alloys. In the computer indus- try, they are used to etch silicon wafers during the manufacture of computer chips. In the chemical industry, they are used as catalysts and fluorinating agents.

8.11-A PRODUCTION OF HYDROFLUORIC ACID Hydrofluoric acid is prepared by reacting sulfuric acid with calcium fluoride, a constituent of the naturally occurring ores fluorspar and fluorite. This production reaction is represented as follows:

CaF2(s) + H 2SO4(conc) CaS04(s) + 2HF(aq) Calcium fluoride Sulfmic acid Calci um sulfate Hydrofluoric acid

The concentrated hydrofluoric acid of commerce is a liquid solution containing 70% hydrogen ~~ride ~y mass. A solution containing 49% hydrofluori~ aci~ is also ava~able commercially.

Physical properties of these three forms of hydrofluoric acid are noted m Table 8.13. fl ~he calcium sulfate is filtered from the resulting mixture, and the solution of hydro- Uoric acid is boiled until the desired concentration is achieved.

8 ' 11

·8 ILL EFFECTS CAUSED BY EXPOSURE TO HYDROFLUORIC ACID Altha h · 'd · k 'd b h h 1· 'd andi ug the data in Table 8.1 show that hydrofluoric aci 1s a wea aci , ot t e iqw the st~ Vapor permeate the skin and produce severe burns t~at heal very slowly. Although u kin damag · ll . bl as external destruction to the outermost layer, the nder[ . e 1s genera y not1cea e

Ying tissues may also be severely damaged.

Hydrofluoric acid

Chapter 8 Chemistry of Some Corrosive Materials 2S

hypocalcemia The adverse health condi- tion associated with low concentrations of calcium in the bloodstream

Anhydrous hydrogen fluoride

TABLE 8.13

ANHYDROUS HF(/) (AHF} HF(aq} (49%} HF(aq) (70%)

Melting point -118°F (-84°C) -34°F (-37°() -96oF (-71'C) Boiling point 67°F (20°C) 224°F (106°C) 151 °F (66'C) Specific gravity at 70°F (21 °C) 0.97 1.16 1.225 Vapor density (air = 1) 70°F (21 °C) 2.21 1.175 1.76 Vapor pressure at 70°F (21 °C) 776 mmHg 27 mmHg 110 mmHg Solubility in water Infinitely soluble Infinitely soluble Infinitely soluble

Exposure of the skin to hydrofluoric acid may be fatal because it can cause hypocalce . during which calcium fluoride precipitates in the body's tissues and removes calcium frornrn~, bloodstream. Calcium is essential for blood clotting and normal muscle and nerve funct' t e Its absence in the bloodstream may cause cardiac arrest. To avoid or reduce the impact ins. the ill effects caused by exposure to hydrofluoric acid, it is essential to follow the first-o~d · · d a1 mstruct:J.ons note in Figure 8.5.

The pain associated with exposure to hydrofluoric acid may not be iillillediately expe- rienced, and the visible signs of corrosion may be unapparent until hours after the initial exposure. At this point, the area of contact may appear blanched and bloodless. Gangrene may develop if the wound is left unattended. The acid may penetrate into the bones where decalcification can also occur. Specialized medical treatment following exposure t~ the acid or its fumes is often necessary. This specialized medical treatment includes injec- tion of calcium-containing substances into burned areas or into the bloodstream.

8.11 -C REACTIONS OF HYDROFLUORIC ACID WITH SILICON COMPOUNDS

The most distinguishing chemical property of concentrated hydrofluoric acid is its ability to slowly react with silicon compounds to produce gaseous silicon tetrafluoride. Silicon compounds are components of ordinary glass. Hydrofluoric acid reacts with them to pro- duce silicon tetrafluoride. For example, hydrofluoric acid reacts with the sodium silicate and calcium silicate in glass as follows:

Na2Si03(s) + 6HF(conc) 2NaF(aq) + SiF4(g) + 3H20(l) Sodium silicate Hydrofluoric acid Sodium fluoride Silicon tetrachloride Water

CaSi03(s) + 6HF(conc) CaF2(s) + SiF4(g) + 3H20(l) Calcium silicate Hydrofluoric acid Calcium flumide Silicon tetrac hloride Water

Because hydrofluoric acid reacts with the components of glass, the acid is routinely stored and transported in polyethylene or other hydrofluoric acid-resistant plastic bottles and drums.

8.11 -0 ANHYDROUS HYDROGEN FLUORIDE dr fl . acid, is Anhydrous hydrogen fluoride (AHF), sometimes called anhydrous hy o uonc 'de

itself a commercial chemical product. Like its solutions, it is prepared from calcium :u;~us and sulfuric acid. The physical properties listed in Table 8.13 illustrate that an Y r hydrogen fluoride readily vaporizes near room temperature. duce

Anhydrous hydrogen fluoride is used mainly in the chemical industry t_o 15). chlorofluorocarbons, hydrofluorocarbons, and hydrochlorofluorocarbons (Sectwn . ·

0 0 /

In the petroleum refining industry, it is used as an alkylate catalyst for the productJ~sses high-octane fuels (Section 12.13-E). It is also used during uranium-enrichment proc

292 Chapter 8 Chemistry of Some Corrosive Materials

/. ) I I FIRST AID a

:-.. f I ')

EXPOSURE FOR HYDROFLUORIC ACID

SEEK IMMEDIATE MEDICAL ATTENTION CALL 911

SERIOUS TISSUE DAMAGE WITH DELAYED ONSET

SKIN CONTACT • IMMEDIATELY (within seconds) proceed to the NEAREST SAFETY

SHOWER and wash affected area FOR 5 MINUTES . • REMOVE all contaminated CLOTHING while in the shower. • WITH NITRILE DOUBLE-GLOVED HANDS MASSAGE CALCIUM GLUCONATE GEL into the affected area. If calcium gluconate gel is not available, wash area for at least 15 minutes or until emergency medical assistance arrives .

• REAPPLY CALCIUM GLUCONATE GEL and massage it into affected area EVERY 15 MINUTES until medical assistance arrives or pain disappears.

EYE CONTACT • IMMEDIATELY (within seconds) proceed TO THE NEAREST EYEWASH

STATION. • Thoroughly WASH EYES WITH WATER FOR AT LEAST 15 MINUTES while holding eyelids open.

Ill • 00 NOT APPLY CALCIUM GLUCONATE GEL TO EYES.

INHALATION • GET MEDICAL ASSISTANCE by calling 911 ·

. . . f • d' 'duals who have been exposed to hydrofluoric acid. (Courtesy of the Department of FIGURE 8.5 This poster provides first-aid instructions or in iv_, Environmental Health & Safety, University of Washington, Seattle, Washmgton.)

(S · . fl · d a gas essential for the production of ection 16.9-D) to prepare uramum hexa uon e, Ura· 'd t

lllum fuel for the nuclear power m_ us r:: 15

m) of anhydrous hydrogen fluoride is . . Exposure to even low concentrations (_ PP ays and lung surfaces. Prolonged U:rit t' h b hial passagew el( a Ing to the eyes, skin, and t e ronc ment of pulmonary edema. .

Posure to the vapor may cause the develop h d en fluoride severely corrodes skm t. As With its solutions contact with anhydrouhs Yk_rogThe tissue corrosion may become issue d ' d beneath t e s m.

an produces severe burns eep Chapter 8 Chemistry of Some Corrosive Materials 293

(g ::--..~) FIRST AID 1 ,w I FOR HYDROFLUORIC ACID

1/~ EXPOSURE

SEEK IMMEDIATE MEDICAL ATTENTION CALL 911

SERIOUS TISSUE DAMAGE WITH DELAYED ONSET

SKIN CONTACT • IMMEDIATELY (within seconds) proceed to the NEAREST SAFETY

• REAPPLY CALCIUM GLUCONATE GEL and massage it into affected area EVERY 15 MINUTES until medical assistance arrives or pain disappears.

EVE CONTACT • IMMEDIATELY (within seconds) proceed TO THE NEAREST EYEWASH

STATION.

• Thoroughly WASH EYES WITH WATER FOR AT LEAST 15 MINUTES while holding eyelids open.

• DO NOT APPLY CALCIUM GLUCONATE GEL TO EYES.

INHALATION • GET MEDICAL ASSISTANCE by calling 911.

FIGURE 8.5 This poster provides first-aid instructions for individuals who have been exposed to hydrofluoric acid. (Courtesy of the Department of En~ronmental Health & Safety, University of Washington, Seattle, Washington.)

(Section 16.9-D) to prepare uranium hexafluoride, a gas essential for the production of urallJum fuel for the nuclear power industry. . . . . Exposure to even low concentrations ( < 15 ppm) of anhydrous hydrogen fluoride 1s Irritating to the k' d th bronchial passageways and lung surfaces. Prolonged ex eyes, s m, an e d

Posure to the vapor may cause the development of pulmonary_ e ema. . . As With its s I · 'th anhydrous hydrogen fluoride severely corrodes skm tissu o ut1ons, contact w1 . . b

e and prod b d b neath the skin. The tissue corrosion may ecome uces severe urns eep e Chapter 8 Chemistry of Some Corrosive Materials 293

Phosphoric acid

TABLE 8.14 Shipping Descriptions of Hydrofluoric Acid and Hydrogen Fluoride

HYDROFLUORIC ACID/HYDROGEN FLUORIDE SHIPPING DESCRIPTION

Hydrofluoric acid (contains not more than 60% strength)

UN1790, Hydrofluoric acid solution 8 (6 l) ' . • PG 11

Hydrofluoric acid (contains more than 60% strength)

Hydrogen fluoride, anhydrous

UN1790, Hydrofluoric acid solution 8 (6 l) ' ' • 'PG I

UN1052, Hydrogen fluoride, anhydrous, 8 16 PG I (Poison - Inhalation Hazard, Zone C) ' .l),

evident only hours following the initial exposure with no immediate experience of Pai Vapor burns to the eyes may result in the formation of lesions or may cause blindness. n.

8 .11 -E WORKPLACE REGULATIONS INVOLVING HYDROGEN FLUORIDE In the workplace, OSHA requires employers to limit employee exposure to a maxi- mum hydrogen fluoride vapor concentration of 3 parts per million, averaged over an 8-hour workday.

8 .11-F TRANSPORTING HYDROFLUORIC ACID AND ANHYDROUS HYDROGEN FLUORIDE

Hydrofluoric acid and anhydrous hydrogen fluoride are transported as liquids. When shippers offer these compounds for transportation, DOT requires them to provide the relevant shipping description shown in Table 8.14 on the accompanying shipping paper. All labeling, marking, and placarding requirements apply.

8.12 PHOSPHORIC ACID Although there are at least eight mineral acids containing phosphorus, phosphoric acid is the only one that is commonly encountered. Its chemical formula is H 3PO4 •

Phosphoric acid is most familiar to the general public as a constituent of certain household cleaning products like Lime-Away. In the chemical industry, it is used as a raw material for manufacturing organophosphate pesticides (Section 10.20) and a number of commercially important metallic phosphates. For instance, phosphoric acid is used to produce superphosphate fertilizer, a synthetic fertilizer consisting of a mixture of calcium dihydrogen phosphate and calcium sulfate. Phosphoric acid is also used to produce mono- ammonium phosphate, the dry-chemical fire extinguisher (Section 5.15-B). It is also used to prepare the surface of steel sheets before painting.

8 .12-A PRODUCTION OF PHOSPHORIC ACID Phosphoric acid is manufactured from phosphate rock, an ore containing calcium phos· phate, by either of the following methods:

In the first method, phosphate rock is reacted with sulfuric acid.

Ca3(P04)z(s) + 3H2S04(aq) - 3CaS04(s) + 2H3P04(aq) Calcium phosphate Sulfuric acid Calci um su lfate Phosphoric acid

The calcium sulfate is filtered from the acid. h In the second method, elemental phosphorus is produced from phosphate rock; then, t e phosphorus is burned to fo rm tetraphosphorus decoxide, which is reacted with water.

294 Chapter 8 Chemistry of Some Corrosive Materials

Melting point

soiling point

Specific gravity at 68°F (20° C)

vapor density (air = 1) vapor pressu re at 68°F (20°C)

solubil ity in water

108°F (42°C)

500°F (260°C)

1.69

3.4

0.0285 mmHg

Very soluble

P4(s) + 502(g) P40 1o(s) Phosp horus Oxygen Tetraphos phorus decoxide

P40 1o(s) + 6H20(l) 4H3P04(aq) Tetraphosphorus decox ide Water Phosphoric acid

The reaction between tetraphosphorus decoxide and water is especially violent and releases considerable heat, 41 kilojoules/mole.

Various grades of phosphoric acid are commercially available. When an aqueous solution of phosphoric acid is allowed to boil at atmospheric pressure, a syrupy solution containing about 85% phosphoric acid by mass is produced. This is the concentrated phosphoric acid of commerce, some physical properties of which are noted in Table 8.15. In addition, a commercially available food-grade phosphoric acid is used as an ingredient of certain soft drinks and other food products.

Phosphoric acid exhibits the hazardous features of all corrosive materials: It reacts with metals, metallic oxides, and metallic carbonates, and it damages skin tissue.

8.12-8 PHOSPHORIC ANHYDRIDE Tetraphosphorus decoxide, or phosphoric anhydride, is the acidic anhydride of phosphoric acid. Its chemical formula is P 4 010, This substance has such a strong affinity for water that it is used industrially as a drying agent.

Because its reaction with water releases 41 kilojoules/mole into the surroundings, phosphoric anhydride should be segregated from combustible matter to prevent its inad- vertent ignition. This amount of heat also causes thermal burns when the oxide comes in contact with the skin.

8.12-C TRANSPORTING PHOSPHORIC ACID AND PHOSPHORIC ANHYDRIDE

When shippers offer phosphoric acid or phosphoric anhydride for transportation, DOT requires them to provide the relevant shipping description shown in Table 8.16 on the accompanying shipping paper. All labeling, marking, and placarding requirements apply.

TABLE 8.16 Shipping Descriptions of Phosphoric Acid and Phosphoric Anhydride

PHOSPHORIC ACID/PHOSPHORUS ANHYDRIDE Phosphoric acid, solid

SHIPPING DESCRIPTION

UN1805, Phosphoric acid, solid, 8, PG 111

UN1805, Phosphoric acid solution, 8, PG Ill

UN1807, Phosphorus pentoxide, 8, PG II

Phosphoric acid solutions Phosphoric anhydride

Phosphoric anhydride

Chapter 8 Chemistry of Some Corrosive Materials

TABLE 8.15 Physical Properties of Concentrated Phosphoric Acid

Melting point soiling point Speci fic gravity at 68°F (20°C) vapor dens ity (air = 1) vapor pressure at 68°F (20°C)

solubility in water

Phospho rus

1 os·F (42°cJ 500°F c2Go 0 cJ 1.69 3.4

0.0285 mm Hg Very soluble

Oxygen Tetraphosphorus decoxide

P40 10(s) + 6H20(/) - 4H3P04(aq) Telraphosphorus decoxide Water Phosphoric acid

The reaction between tetraphosphorus decoxide and water is especially violent and releases considerable heat, 41 kilojoules/mole.

Phosphoric acid exhibits the hazardous features of all corrosive materials: It reacts with metals, metallic oxides, and metallic carbonates, and it damages skin tissue.

8.12-B PHOSPHORIC ANHYDRIDE Tetraphosphorus decoxide, or phosphoric anhydride, is the acidic anhydride of phosphoric acid. Its chemical formula is P4 0 10• This substance has such a strong affinity for water that it is used industrially as a drying agent.

8,12-C TRANSPORTING PHOSPHORIC ACID AND PHOSPHORIC ANHYDRIDE

TABLE 8.16

PfiOSPHORIC ACID/PHOSPHORUS ANHYDRIDE SHIPPING DESCRIPTION Phosphor~ic_a_c,:._:· d.:, s::o:.::li:_:d..:..::::~~.::::_:~::::~==-=----+-U- N- 18::--:0:-::5:--, ::Ph:--o- s-p:-h-or--:-ic_a_c--:-id-:-,-s-o;:-lid-:-,--:8:--, ::PG~ ll:-1 -

Phosphor-:-i_c~a-c_i..:::dt s:.:o~l:..::u~t~io; n; s~~~~~~~~~~~~~~~~~~~~~~ ~U~N~1~8~0::5--:-,~P~h~o~s~p--:-h~o~r-:--i_c~a~c:-i-::d~s~o~lu~t-:--i_o~n-,:--::8:-,~P~G~ -::-:I_II Phosph . 'd one anhydride UN1807, Phosphorus pentox, e, 8, PG II

Phosphoric anhydride

Chapter 8 Chemistry of Some Corrosive Materials 295

R, &

SOLVED EXERCISE 8.4

Glacial acetic acid

¢.

What UN marking is em bossed on the bottom of a lined, openhead steel drum used for the transport . phosphoric acid if the drum was manufacture d in 2010 in the United States by a manufacturer whose re ~tion of number is M-xxx?

915 lration

Solution: Based on t he information in Table 6.6, an openhead steel drum is identified by the code .. 1A2,, , is used to identify Packing Group Ill. The _s pecific_ gravity of phosphoric acid is ~rovided in Table a. 1 s as 7_·6 '2" 1 . 7. The test pressure for the steel drum 1s 1 00 kilopasca_ls; 10 1s t~e last two d1g1ts o'. the year in which the~· or drum was manufactured in the United States; and M-xxx 1s the reg1strat1on number of its manufacturer G' tee1 combination of information, DOT requ ires the following marking to be embossed on the bottom of a ·st~~~~ this intended for t he tra nsportation of phosphoric acid : ruin

(]) 1A2/Z1.7/100/10/USA/M-xxx, or UN1A2/Z7.1/100/10/USA/M-xxx

' £ . t J

8.13 ACETIC ACID Acetic acid is the most commonly encountered organic acid. Its chemical formula is CH 3COOH , or H C2H 30 2 • Each molecule of aceti~ acid is represented by the following Lewis structure:

H 0 I //

H-C-C I \

H OH

Acetic acid is the substance responsible for the sour taste and sharp odor of vine· gar, the common food product containing from 3 % to 6 % acetic acid by volume. It is used primarily by the chemical industry as a raw material for the synthesis of ethyl acetate, vinyl acetate, cellulose acetate, and other chemical and pharmaceutical products .

8.13-A PRODUCTION OF ACETIC ACID Chemical manufacturers produce acetic acid by a number of methods, the most popular of which involves the gas-phase combination of methanol and carbon monoxide.

Methano l Carbon monox ide Acetic ac id

When aqueous solutions of acetic acid are cooled to temperatures near 61 °F !1 6°C1'. a mixture of liquid and solid phases is produced. The liquid phase contains imPt ties and is recycled or discarded, but the solid phase typically contains more t a~ 99% acetic acid by mass. This component is the concentrated acetic acid of coJ1ld merce, called glacial acetic acid. When encountered, it is generally stored in glass an plastic containers.

296 Chapter 8 Chemistry of Some Corrosive Materials

TABLE 8.17 Physical Properties of Concentrated Acetic Acid

Melting point

Boil ing point specific gravity at 68°F (20°()

vapor density (a ir = 1) vapor pressure at 68°F (20 °C)

Flashpoint Auto ignition point Lower flammable lim it Upper flammable limit

Solubility in water

61°F (17°C)

244°F c11s 0 c)

1.05

2.1

11 mmHg 109°F (43°C)

soo·F (426°()

4% by volume 19.9% by volume Infinitely soluble

At room temperature, glacial acetic acid is a colorless, pungent liquid. Some of its important physical properties are noted in Table 8.17. Other varieties are also available commercially containing from 80 % to 99 % acid by mass.

8.13-B VAPORIZATION OF ACETIC ACID Concentrated acetic acid releases a vapor, which, when inhaled, is choking and suffocat- ing and can readily damage the bronchial tract. Exposure to other body tissues, particu- larly the eyes, results in severe burns.

8.13-C COMBUSTIBLE NATURE OF ACETIC ACID Co ncentrated acetic acid is an OSHA category 3 flammable liquid (NFPA class II co mbustible liquid ), but aqueous solutions of acetic acid containing less than 80% aci d are nonflammable. The complete combustion of acetic acid vapor is represented as follows:

0 //

CHrC(g ) + 20i(g) - 2COz(g) + 2H20(g) \ OH

Acet ic acid Oxygen Carbon d ioxide Water

Fires involving concentrated acetic acid may be extinguished by diluting the acid with water.

8,13-D WORKPLACE REGULATIONS INVOLVING ACETIC ACID the workplace, OSHA requires employers to limit employee exposu re to a maxi-

um acetic acid va por concentration of 10 parts per million , averaged over an ·hour workday.

,13-E TRANSPORTING ACETIC ACID en shippers offer acetic acid or its solutions for transporta tion, DOT requires them to

'.0vide the relevant shipping description shown in Table 8.18 on the accompanying ship- ing Pape r. All labeling, marking, and placarding requirements apply.

Chapter 8 Chemistry of Some Corrosive Materials 297

Sodium hydroxide

Potassium hydroxide

TABLE 8.18 Shipping Descriptions of Acetic Acid

FORM OF ACETIC ACID SHIPPING DESCRIPTION

Acetic acid (contains more than 10% but not more than UN2790, Acetic acid solution 8 50% acid by mass) ' • PG Ill -:----.----------------------------j------- - - A c et ic acid solution (contains not less than 50% but not UN2790, Acetic acid solution 8 more than 80% acid by mass) ' • PG II ----------------------------j-- - - ----- A c et i c acid, glacial (contains more than 80% acid by mass) UN2789, Acetic acid, glacial 8 (3) ' ' • PG II Acetic acid solution (contains more than 80% acid by mass) UN2789, Acetic acid solution 8 (3) , , , PG11

8.14 SODIUM HYDROXIDE, POTASSIUM HYDROXIDE AND CALCIUM HYDROXIDE '

There are three commercially important corrosive materials that are alkaline: sodi hydroxide, potassium hydroxide, and calcium hydroxide. Their chemical formulas urn N a OH , KO H , and Ca (OH )i, respectively. Their physical properties are noted collectiv:;e in Table 8.19. y

To the layperson, sodium hydroxide is best known as a constituent of consumer prod- ucts such as Drano and Liquid-Plumr, which are used to unclog drainage pipes, and oven cleaners like Easy-Off. Sodium hydroxide solutions are also used as industrial cleaners at car- and truck-washing facilities and garages, and they are used at wastewater facilities to isolate metallic compounds as water-insoluble metallic hydroxides.

Sodium hydroxide is industrially used in countless applications including the purifi- cation of petroleum products, the reclaiming of rubber, and the processing of textiles and paper. The chemical industry uses large amounts of sodium hydroxide as a raw material during the manufacturing of soap, rayon, cellophane, and numerous commercial chemical substances.

Potassium hydroxide is used mainly by the chemical industry for the production of compounds like fertilizers, soft soaps, and pharmaceutical products. It is also the electrolyte in alkaline storage batteries. Potassium hydroxide was formerly used in liquid drain cleaners, but at 16 C.F.R. §1500.17, CPSC now bans the manufacture and sale of cleaners containing potassium hydroxide at a concentration of 10% or more by weight.

Calcium hydroxide is primarily used as a raw material for the production of mor- tar, plaster, and cement, but it is also widely used commercially for other purposes. Emergency responders use it to neutralize acids when they have been unintentionally released from their containers. A food grade of calcium hydroxide is a component of some antacids.

TABLE 8.19 Physical Properties of Several Metallic Hydroxides

Melting point

Boiling point

Specific gravity at 68°F (20°C)

Solubility in 100 g of water

SODIUM HYDROXIDE

s99°F (31 s 0 c)

2534°F (1390°c)

2.13

42 g

POTASSIUM CALCIUM HYDROXIDE HYDROXIDE

680°F (360°() 1076°F (SBO'C)

24os°F c132o·ci Decomposes

2.04 2.50

107 g 0.18 g

298 Chapter 8 Chemistry of Some Corrosive Materials

S 14 . A PRO D UCTION OF SODIUM HYDROXIDE . AND POTASSIUM HYDROXIDE d' m hydroxide and potassium hydr 'd

So iu_ urrent through solut'o f odx_1 e are generally manufactured by passing an eJecrnc_ c I

I ns O so ium chloride (brine) and potassium chloride, respecnve y.

2N aC l (aq) + 2H20(i) ---. 2NaOH(a~/) Sodi,1111 c hl o ride Water + H2(g) + C l2(g )

Sod ium hydroxide 2KC l(aq) +

Po1ass ium hydroxide Hydroge n Chlorine Potassi um chl oride Water

2KOH(aq) + Hydroge n Chl o,inc

om temperature, they are comme · JI ·1 bl • ul At ro d . rcia Y ava1 a e as flakes pellets sucks gran es, d ncentrate aqueous solutions Th · d · I ' • ' • ' an co d . · e m ustna forms of sodium hydroxide are also as lye an caustic soda wherea th f f • • · known ' s e arms o potassium hydroXJde are called caustic potash and potash lye.

s.14-B PRODUCTION OF CALCIUM HYDROXIDE Calcium hydroxide is ind ustrially prepared by reacting calcium oxide and water as follows:

CaO(s) + Calciu m oxide

H 20(/) ---. Ca(OH)2(s) Water Calcium hyd roxide

This reaction is called slaking, which gives rise to slaked lime the industrial name of calcium hydroxide. Calcium oxide is called unslaked lime and quicklime.

8.14-C TRANSPORTING SODIUM HYDROXIDE, POTASSIUM HYDROXIDE, AND CALCIUM HYDROXIDE

When shippers intend to transport sodium hydroxide, potassium hydroxide, and cal- cium hydroxide, DOT requires them to provide the relevant shipping description in Table 8.20 on the accompanying shipping paper. All labeling, marking, and placarding requirements apply.

DOT regulates the transportation of calcium oxide by air only. Hence, shippers are obligated to affix a CARGO AIRCRAFT ONLY label in addition to the CORROSIVE label to its packaging.

When carriers transport 1001 pounds (454 kg) or more of these substances, DOT requires them to display CORROSIVE placards on the bulk packaging used for shipment as shown in Figure 8.6.

DOT does not regulate the transportation of calcium hydroxide.

TABLE 8.20 Shipping Descriptions of Some Alkaline Substances

~KALINE SUBSTANCE

~cium oxide (unslaked lime) Potassium hydroxide, solid

Potassium hydroxide solution Sodium hydroxide, solid

Sodium hydroxide, solution

SHIPPING DESCRIPTION

UN1910, Calcium oxide, 8, PG Ill

UN1813, Potassium hydroxide, solid, 8, PG II UN1814, Potassium hydroxide, solution, 8, PG II

UN1823, Sodium hydroxide solid, 8, PG II UN1824, Sodium hydroxide, solution, 8, PG II

slaking The chemical process associated with reacting calcium oxide (unslaked lime) with water to form calcium hydroxide

Chapter 8 Chemistry of Some Corrosive Materials 299

RCRA corrosivity characteristic For purposes of RCRA regulations, the characteristic of either liquid waste noted at 40 C.F.R. §261 .22

FIGURE 8 .6 When carriers transport a sodium hydroxide solution, DOT requires them to display the identifi- cation number 1824 across the center area of the CORROSIVE placards posted on the transport vehicle. DOT also permits the identification number to be displayed on orange panels or white square-on-point diamonds. (Courtesy of Bulk Transportation, Inc., Wa lnut, California.)

8.15 RCRA CORROSIVITY CHARACTERISTIC As first noted in Section 1.3-C, EPA uses the legal authority of RCRA to regulate the treatment, storage, and disposal of hazardous wastes that exhibit certain characteristics, one of which is corrosivity.

At 40 C.F.R. §261.22, a waste exhibits the RCRA corrosivity characteristic when it is either of the following:

An aqueous liquid that has a pH less than or equal to 2 or greater than or equal to 12.5. A liquid that corrodes steel at a rate greater than 0.25 inches/year (6.25 mm/y) at a test temperature of 130°F (55°C) using a specified test method.

A waste that exhibits the RCRA corrosivity characteristic is assigned the hazardous waste number D002.

8.16 WORKPLACE REGULATIONS INVOLVING CORROSIVE MATERIALS

Among its other responsibilities, OSHA is charged with protecting workers from the ill effects caused by exposure to corrosive materials. To accomplish this aim, it reqmres employers to display accident-prevention tags, warning labels, and worded signs that sig- nal the presence of corrosive materials in the workplace when exposure could damage property or cause accidental injury to workers. Some examples that relate to identifying corrosive acids and bases are shown in Figure 8. 7.

300 Chapter 8 Chemistry of Some Corrosive Materials

..........

ACID , QANGEFI'

Wear Gloves When Handling Acid or Caustics

·oANGEfL: - .

Caustic

. - DANGER '_,

Wear Gloves and Rubber Gloves When Handling

Chemicals

FIGURE 8.7 OSHA requires employers to post worded signs that warn employees of the presence of corrosive materials in the workplace , OSHA also requires employers at 29 C.F.R. § 1200(h)(3)(iv) to affix accident- prevention tags or warning labels to their in-plant containers of corrosive materials.

Corrosi ve materials are frequently used in science laboratories and in certain work environments. In all areas where individuals may be exposed to an injurious corrosive material, OSHA requires the availability of suitable facilities for quick drenching and flushing of the eyes and body. An example of a suitable eyewash station and shower is shown in Figure 8.8.

FIGURE 8 .8 OSHA requires employers at 29 C.F.R. §1910.Sl(c) to provide emergency-use eyewash units and drench showers in areas where employees may be exposed to corrosive materials. Each eyewash unit and shower should deliver 4 gallons/minute and 20 gallons/minute of water, respectively, during a 15-minute period.

Chapter 8 Chemistry of Some Corrosive Materials 301

8.17 RESPONDING TO INCIDENTS INVOLVING A RELEASE OF A CORROSIVE MATERIAL

First-on-the-scene responders may generally identify the presence of a corrosive at the emergency scene by reference to the NFPA hazard diamond affixed or imp ?1aterial its storage vessel. Any of the expressions ACID, ALK, or CORR may appear i:~~ed on tom quadrant of the hazard diagram. They rapidly convey the message that a co/ b?t• material is contained within the vessel. roSive

At a transportation mishap, emergency responders identify the presence of a corr . material by observing the following: OSive

The number 8 as a component of a shipping description of a hazardous material ll . . sted on a sh1ppmg paper The word CORROSIVE and the number 8 printed on black-and-white labels aff' d . d ll(e to containment evices The word CORROSIVE and the number 8 printed on black-and-white placards displayed on each side and each end of a transport vehicle containing 1001 pounds (454 kg) or more of a corrosive material

At an emergency scene involving a corrosive material, the members of the response crew should conduct their work only while wearing fully encapsulated entry suits with clear face shields . Because these suits are fabricated from a material through which the corrosive material cannot penetrate, they protect their wearers from bodily contact with it. The firefighter shown in Figure 8.9 is wearing an "Entry 1-suit," which provides suf- ficient protection to work without the fear of exposure to a corrosive material.

FIGURE 8 .9 This firefighter is wearing a fully encapsulating body suit for responding to an emergency incident involving the release of a cor- rosive material into the environment. The chemical nature of the fabric prevents bodily contact with the corrosive material. Self-contained breathing apparatus is also essential when responding to emergencies in which the corrosive material possesses a significant vapor pressure . (Courtesy of Lakeland Industries, Inc., Ronkonkoma, New York; Image O 2012, All Rights Reserved.)

302 Chapter 8 Chemistry of Some Corrosive Materials

Althou~h fu!ly enc~psulated entry suits are not themselves designed to protect their users from inhalmg to~ic vapors or fumes, apparel equipped with self-contained breath- ing apparatus (S_CBA) is n:iarketed for use _ by_ e_mergency responders. When a bulk quan- . of a corrosive matenal that has a s1gmficant vapor pressure is encountered, the

utY t SCBA . dd . · · · h responders mus ~se m a 1t10n to wearmg these suits. Examples of acids t at s ontaneously emit harmful vapors are oleum, fuming nitric acid, concentrated hydro- hJoric acid, and concentrated acetic acid.

c When they are called to a scene involving the release of a corrosive material, emer- gency responders should consider the following actions:

1 Dilute the corrosive material with an approximate volume of water equal to at least 10 times the volume of the material that has been released into the environment. This is usually an adequate response when relatively small quantities of an acid or base ha ve spilled o~ leaked. fr~m a co~tainer or storage tank. For instance, suppose that a I-gallon contamer of hqwd sulfunc acid has inadvertently been spilled on a laboratory floor and has flowed toward a drain leading to an off-site wastewater treatment plant. In this situation, dilution of the spilled acid with a copious volume of water lessens the acid's corrosive nature.

Special care should be exercised to avoid inhaling the fumes that arise when diluting fuming sulfuric acid, fuming nitric acid, concentrated hydrochloric acid, and concentrated acetic acid. The inhalation of these fumes poses the risk of inhalation toxicity because the fumes can seriously damage the respiratory system.

I Neutralize the corrosive material. This action is recommended when a crew re- sponds to the environmental release of a relatively large volume of a corrosive material such as a leak of 10,000 gallons (38 m 3) of an acid from a storage tank or during a transportation mishap. It generally is impractical to dilute such a large volume of a cor- rosive material with water, because an even larger volume of water is needed to effectively reduce its corrosiveness.

A large volume of an acid may be effectively neutralized with solid substances such as either slaked lime or soda ash, the common names for calcium hydroxide and anhy- drous sodium carbonate, respectively. As noted in Section 8.3, an acid reacts with a base to produce a salt of the acid and water; and an acid reacts with a metallic carbonate to produce a salt of the acid, water, and carbon dioxide.

When slaked lime or soda ash is used to neutralize a spill of hydrochloric acid, the resulting chemical reactions may be represented by the following equations:

Ca(OH)z(s) + 2HCl(aq) CaClz(aq) + 2H20(l) Calcium hydroxide Hydrochloric acid Calcium chloride Water

Na2C03(s) + 2HCl(aq) 2NaCl(aq) + C02(g) + H20(l) Sodium carbonate Hydrochloric ac id Sodium chloride Carbon dioxide Wate r

The use of slaked lime or soda ash results in reducing or eliminating the corrosive nature of hydrochloric acid by chemically converting it into a group of relatively benign substances. . W_hen first-on-the-scene emergency responders are called to a transportation mishap involving the release a bulk shipment of hydrogen chloride or hydrogen fluoride, they :ust acknowledge that the vapor could cause serious respiratory damage to the team, r/nsportation personnel and the general public. The Emergency Response Guidebook

commend · 1 · ' · · f 1 ·11 f h b tn ulf 1

5 iso at1on and evacuation distances or arge spt s o t ese su stances from or tr

1 ~1 e srnall cylinders or single ton cylinders, multiple ton cylinders, highway tank trucks

ton ttJ and rail tankcars (for hydrogen chloride) and multiple small cylinders or single yin ers, highway tank trucks or trailers, and rail tankcars (for hydrogen fluoride). 1

~E , merge Pp. 354_355 ncy Response Guidebook (Washington, DC: U.S. Department of Transportation, 2012),

Chapter 8 Chemistry of Some Corrosive Materials 303

r I SOLVED EXERCISE 8.5

First-on-the-scene responde rs arriving at a domestic transportation _mishap _obse~e· th at a 5000-gallon (lg. 3 overturned tank truck is leaking its liquid contents. The transportation marnfeSt 1nd1 cates that the consign rn I consists solely of concentrated hydroc hlo ric acid . The hi ghway o n which the truck was traveling is located ap:~nt imately 250 feet (76.2 m) from th e e dge of a la ke . What procedures should th ese flrS t responders impleme nt ~ save lives , property, and the environment? Solution: Hydrochloric acid is a corrosive material. Co nsequently, first responders must don an acid-impeo,;0, 1 su it that has been designed to prevent bodily conta ct with a corrosive material. Anoth er hazard assooated . concentrated hydrochlor ic acid is exposu re to the vapor that_ spontaneo_usly evolves from the liquid . To a:: inhaling this vapor, emergency responders must use se lf-contained breathing apparatus . . .

To save lives, property, and the environment , fi rst -o n-the-scene responders should consider implementation of the following procedures:

• Use self-conta ined breathing ap paratu s. Wear special protective clothing.

• Use water fog or foam to reduce toxic ga s f umes in the air. Dike or dam the spilled material t o pre vent it s spread. Use slaked lime to neutralize the aci d withi n t he diked area .

8.18 RESPONDING TO INCIDENTS INVOLVING ACID AND ALKALI POISONING

Paramedic teams are often called to assist in situations in which individuals have inadver- tently been exposed to corrosive materials. In such incidents, a member of the paramedic team should immediately contact the American Association of Poison Control Centers.2

In addition, the following actions are appropriate: Because corrosive materials can irreversibly alter skin tissue at the site of contact,

the affected area should be thoroughly flushed with water. When a corrosive material has been inadvertently splashed into an individual's

eyes, pain, swelling, corneal erosion, and blindness can rapidly ensue. Consequently, it is vital to immediately flush the eyes with a gentle stream of running water for at least 30 minutes (lifting the upper and lower lids occasionally). If the individual is wearing contact lenses, the eyes should first be irrigated for several minutes, and then, the lenses should be removed and the eyes again irrigated. The individual should be advised to promptly contact an ophthalmologist for professional eye treatment.

When a corrosive material has been ingested, the individual may experience difficulty in swallowing, nausea, intense thirst, shock, difficulty in breathing, and death. Vomiting should not be induced unless advised by a physician. The stomach wall is relatively tough and normally capable of withstanding the presence of gastric juices having a pH of less than 2. Vomiting should not be induced, because the individual's stomach contents could inadvertently be channeled into the bronchial tract, where they could cause serious damage. However, paramedics may attempt to neutralize the individual's stomach contents. Milk 0( magnesia, a white suspension of magnesium hydroxide in water, may be used to neutraliz_e acids. A popular brand is Phillips' Milk of Magnesia, which is often found in home medt· cine cabinets. Acidic foods such as vinegar and citrus fruit juices may be used to neutralize bases. To ensure that the corrosive material has been completely neutralized, the individual should consume a volume of the neutralizing agent at least equal to the amount ingeSted.

2The America_n Association of Poison Control Centers can be accessed by telephone at (800) 222-1 222, lt is ~ssenttally a library staffed by no~edical personnel. Be prepared to give the name of the poisonous producr involved '.nth~ emergency and any information provided on the label. The poison hotline may also be conrac ted when an ind1v1dual overdoses on medication.

304 Chapter 8 Chemistry of Some Corrosive Materials