Although elemental aluminum is stable in the form of foil and sheets, alu :, and powder are pyrophoric materials that pose the risk of fire and explosion ~~tun dust num burns violently in air with an intensely bright, white and orange flame · e alutni. mixture of aluminum oxide and aluminum nitride. producing a 4Al(s) + 30z(g) 2Al203(s) Alnminum Oxygen Aluminum oxide 2Al (s) + N2(g) 2AIN(s) Aluminum Nitrogen Aluminum nitride These reactions may be initiated by the combustion of hydrogen, produced when th and powder react with atmospheric moisture. e dust 2Al(s) + 3H20(/) Al203(s) + 3H2(g) Aluminum Water Aluminum oxide Hydrogen Powdered aluminum burns spontaneously on contact with liquid oxygen. Ahunin oxide is the sole product of combustion. UJn The reactivity of aluminum powder is put to use in the formulations of many fir _ ~arks, i~ whic~ the metal, when activated, burns to pro~uce a bri_lliant disp~ay of oran:e light. It is also mcorporated into certain paints and varmshes for its decorative and heat- reflective features; but consideration must be given to their use, because these coatings may behave as flammable solids once the paint solvent has evaporated. Aluminum pow- der is also a component of solid rocket fuels, in which it is mixed with ammonium nitrate and ammonium perchlorate. The mixture of powdered aluminum and ammonium nitrate is an explosive called ammonal. The catastrophe of the German dirigible Hindenburg may have been linked with the combustion of aluminum powder. The exterior surface of the dirigible consisted. of a cloth cover impregnated with a doping mixture of aluminum powder and ferric oxide. The presence of aluminum powder provided a surface having high reflectivity. The cover was intended to serve an important purpose: The aluminum particles reflected heat off the vessel and prevented the hydrogen from expanding. The prevail- ing theory is that the aluminum powder first caught fire at an isolated location, per- haps triggered by static electricity or lightning. Once initiated, the fire then rapidly spread across the entire covering, ultimately igniting the reserves of hydrogen. The resulting inferno consumed the vessel. In circumstances where the temperature is substantially elevated compared with the norm, even bulk aluminum acts as a fast-burning fuel. The skin of shuttle aircraft, for example, must be armored with heat shielding to protect the shuttle when it reen· ters Earth's atmosphere from outer space, experiencing temperatures in excess of 3000°F (1650°C). If this shielding is pierced in any way, the underlying aluminum becomes superheated. Aluminum melts at 1220°F (660°C) and vaporizes at 4221°F (2327°C). At these temperatures, aluminum fires occur when oxygen is available to support the combustion. In 2003, the space shuttle Columbia disintegrated on reentry into Earth's atmosphere, killing the seven astronauts onboard. The shuttle was covered with more than ...

1. Although elemental aluminum is stable in the form of foil and
sheets, alu :,
and powder are pyrophoric materials that pose the risk of fire
and explosion ~~tun dust
num burns violently in air with an intensely bright, white and
orange flame · e alutni.
mixture of aluminum oxide and aluminum nitride. producing a
4Al(s) + 30z(g) 2Al203(s)
Alnminum Oxygen Aluminum oxide
2Al (s) + N2(g) 2AIN(s)
Aluminum Nitrogen Aluminum nitride
These reactions may be initiated by the combustion of
hydrogen, produced when th
and powder react with atmospheric moisture. e dust
2Al(s) + 3H20(/) Al203(s) + 3H2(g)
Aluminum Water Aluminum oxide
Hydrogen
Powdered aluminum burns spontaneously on contact with liquid
oxygen. Ahunin
oxide is the sole product of combustion. UJn
The reactivity of aluminum powder is put to use in the
formulations of many fir _
~arks, i~ whic~ the metal, when activated, burns to pro~uce a
bri_lliant disp~ay of oran:e
light. It is also mcorporated into certain paints and varmshes for

2. its decorative and heat-
reflective features; but consideration must be given to their use,
because these coatings
may behave as flammable solids once the paint solvent has
evaporated. Aluminum pow-
der is also a component of solid rocket fuels, in which it is
mixed with ammonium nitrate
and ammonium perchlorate. The mixture of powdered aluminum
and ammonium nitrate
is an explosive called ammonal.
The catastrophe of the German dirigible Hindenburg may have
been linked with
the combustion of aluminum powder. The exterior surface of the
dirigible consisted. of
a cloth cover impregnated with a doping mixture of aluminum
powder and ferric
oxide. The presence of aluminum powder provided a surface
having high reflectivity.
The cover was intended to serve an important purpose: The
aluminum particles
reflected heat off the vessel and prevented the hydrogen from
expanding. The prevail-
ing theory is that the aluminum powder first caught fire at an
isolated location, per-
haps triggered by static electricity or lightning. Once initiated,
the fire then rapidly
spread across the entire covering, ultimately igniting the
reserves of hydrogen. The
resulting inferno consumed the vessel.
In circumstances where the temperature is substantially elevated
compared with
the norm, even bulk aluminum acts as a fast-burning fuel. The
skin of shuttle aircraft,
for example, must be armored with heat shielding to protect the

3. shuttle when it reen·
ters Earth's atmosphere from outer space, experiencing
temperatures in excess of
3000°F (1650°C). If this shielding is pierced in any way, the
underlying aluminum
becomes superheated. Aluminum melts at 1220°F (660°C) and
vaporizes at 4221°F
(2327°C). At these temperatures, aluminum fires occur when
oxygen is available to
support the combustion.
In 2003, the space shuttle Columbia disintegrated on reentry
into Earth's atmosphere,
killing the seven astronauts onboard. The shuttle was covered
with more than 20,000
interlocking ceramic tiles designed to protect the aluminum
alloy shell from the heat
0
~
reentry. Experts who examined debris from the accident
wreckage observed droplets
0
aluminum and stainless steel. This observation suggests that the
cause of the accident w~s
linked with the loss of the thermal protective system on the left
wing, especially alo~g its
leading edge. Without its protective covering, the underlying
aluminum alloy most likelY
burned, ultimately destroying the entire shuttle.
322 Chapter 9 Chemistry of Some Water- and Air-Reactive
Substances

4. E IVIETALLIC ZINC
9 3· d · ·1 b • -
5
produce pnman Y Y means of the following two-step thermal
process·
z;inC I . . .
11
First, the zinc sulfide ore sphaler,te, or zinc blende, is roasted
in air to produce zinc oxide.
2ZnS(s) + 302(g) - 2ZnO(s) + 2S02(g)
Zinc sulfide Oxygen Zinc oxide Sulfur dioxide
11
Then, the oxide is reduced with carbon monoxide.
ZnO(s) + CO(g) - Zn (g) + C02(g)
Zinc oxide Carbon monoxide Zinc Carbon dioxide
The zinc vapor _produced by the reaction is then distilled,
condensed, and cast into ingots.
The zinc depos~ts on the walls of the distillation apparatus as a
gray, finely divided pow-
d known as zmc dust. er uf . The zinc man acturmg process is
complicated by the presence of the metal impuri-
ties silver, lead, copper, arsenic, antimony, and manganese, all
of which occur naturally in
sphalerite. These ~etals are rem?ved by a combination of
chemical processes. The manu-
facturing process 1s also complicated by the simultaneous

5. production of the pollutant
sulfur dioxide (Section 10.12), which must be scrubbed from the
off-gas plume generated
during the roasting process.
Metallic zinc is used for several purposes. The metal is coated
on iron products to
protect them from corrosion by the air. This zinc-coated iron is
said to be galvanized.
Zinc is also used as a component of several alloys; for example,
zinc and copper are com-
bined in the molten state to produce brass. Metallic zinc is also
used in the manufacture
of dry-cell batteries and a variety of structural materials. Zinc
dust is a component of
certain primers and rust-resistant paints.
Zinc is hazardous only as its dust. Especially when it is hot,
zinc dust is a pyrophoric
material that poses a fire and explosion hazard. It ignites
spontaneously in air with a green
flame, producing zinc oxide as the sole combustion product.
2Zn(s) + 02(g) 2Zn0(s)
Zinc Oxygen Zinc oxide
The reaction may be initiated by the combustion of hydrogen,
produced when the dust reacts
with atmospheric moisture.
Zn(s) + H20(/) ZnO(s) + H2(g)
Zinc Water Zinc oxide Hydrogen
9.3-F TRANSPORTING COMBUSTIBLE METALS
When shippers offer a combustible metal for transportation,
DOT requires them to iden-

6. tify the appropriate material on the accompanying shipping
paper. Some examples for
several representative combustible metals are listed in Table
9.5. DOT also requires ship-
pers and carriers to comply with all labeling, marking, and
placarding requirements.
When molten aluminum is transported in bulk packaging by
highway or rail, DOT
requires carriers at 49 C.F.R. § 172.325 to mark the packaging
with the expression MOLTEN
ALUMINUM and the identification number 9260 on orange
panels, white square-on-point
diamonds, or HOT markings. The following examples illustrate
the nature of these markings:
Zinc metal
powder/dust
galvanize The process
of coating a metal with
a protective layer of
elemental zinc
Chapter 9 Chemistry of Some Water- and Air-Reactive
Substances 323
TABLE 9.5
COMBUSTIBLE METALS SHIPPING DESCRIPTION
Aluminum, molten NA9260, Aluminum, molten, 9, PG I
Aluminum powder UN1309, Aluminum powder, coated, 4.1, PG
11

7. or
UN1396, Aluminum powder, uncoated, 4.3, PG 11 (Dan
Magnesium (with more than 50% magnesium in pellets
turnings, or ribbons) '
UN1869, Magnesium, 4.1, PG Ill
Magnesium alloys (with more than 50% magnesium in UN1869,
Magnesium alloys, 4.1, PG Ill
pellets, turnings, or ribbons)
Magnesium granules (particle size not less than 149 microns)
UN2950, Magnesium granules, coated, 4.3, PG Ill (Dan
When Wet) Qerous
Magnesium powder UN1418, Magnesium powder, 4.3, (4.2), PG
I (Dangerous
When Wet)
or
UN1418, Magnesium powder, 4.3, (4.2), PG 11 (Dangerous
When Wet)
or
UN1418, Magnesium powder, 4.3, (4.2), PG 111 (Dangerous
When Wet) -Titanium powder UN2546, Titanium powder, dry,
4.2, PG I
Titanium (powder), wetted with not less than 25% water
UN1352, Titanium powder, wetted, 4.1, PG II
(a visible excess of water must be present) (a) mechanically
produced, particle size less than 53 microns; (b) chemically
produced, particle size less than 840 microns
Titanium sponge granules UN2878, Titanium sponge granules,
4.1, PG Ill

8. Titanium sponge powders UN2878, Titanium sponge powders,
4.1, PG Ill
Zinc dust UN1436, Zinc dust, 4.3, (4.2), PG I (Dangerous When
Wet)
Zinc powder UN1436, Zinc powder 4.3, (4.2), PG I (Dangerous
When Wet)
Zirconium, dry (finished sheets, strip, or coil wire) UN2008,
Zirconium, dry, 4.1 PG Ill
Zirconium powder, wetted with not more than 25% water
UN1358, Zirconium powder, wetted, 4.1, PG II
[(a visible excess of water must be present) (a) mechanically
produced, particle size less than 53 microns; (b) chemically
· m'crons produced, particle size less than 840 1
9.4 ALUMINUM ALKYL COMPOUNDS
AND THEIR DERIVATIVES
aluminum alkyl • A
compound whose
molecules are composed
of an aluminum atom
covalently bonded to
three carbon atoms,
each of which is a
component of an
Organometallic substances are compounds whose molecules
have one or more metal
atoms covalently bonded directly to a nonmetal atom. Examples
of organometallic sub·
stances include the aluminum alkyls, whose molecules have an

9. aluminum atom covalently
bonded to three carbon atoms. An example of an aluminum
alkyl compound is triethyl-
aluminum, whose chemical formula is Al(CH2CH3)J, or
Al(C2H5)).
alkyl group
CH2CH3
I
CH3CH2 - Al-CH2CH3
Triethylaluminum
(TEA)
324 Chapter 9 Chemistry of Some Water- and Air-Reactive
Substances
is instance, the ~lkyl grou~ is na~ed ethyl, which has the
formula -CH2CH3. In the
Jo th ical industr~, tnethY1alummum is often designated as
TEA. Its properties are repre-
chern ·ve of aluminum alkyl compounds.
eorau · I r ps of I · lk I I h I'd s rwo specia g ou . a ummum a yl
compounds are the aluminum a ky a es
JUJllinum alkyl hydrides. These compounds are the halide and
hydride derivatives
aod t JJJinum alkyl compounds, respectively, in which one or
two halide or hydrogen
of au substitute for an alkyl group. Examples of these
derivatives are diethylaluminum
at0~:de and diisobutylaluminum hydride, whose formulas are

10. (C2H5 )zAICI and
chi~ ) cHCH2]zAIH, respectively.
[(CP 3 2
Cl H
I I
CH3CH2-Al - CH2CH3 (CH3)zCHCH2-AI - CH2CH(CH3h
Diethylaluminum chloride Diisobutylaluminum hydride
(DEAC) (DIBAH)
The alkyl group having the formula _(CH3)zCHCH2- is named
isobutyl. In the che1?ical
. dustrY, these compou?ds are sometimes designated as DEAC
and DIBAH, respectively.
;~ this section, we consider them as representative of the halide
and hydride derivatives of
all aluminum alkyl ~ompounds. . .
Table 9.6 provides some physical properties of
triethylaluminum, diethylalununum
hloride, and diisobutylaluminum hydride. Chemical
manufacturers display the flame
;icrogram on la_bel~ affixed to containers holding the
aluminum alkyls and their halide
and hydride derivatives.
g,4-A COMMERCIAL USES OF THE ALUMINUM ALKYL
COMPOUNDS
AND THEIR DERIVATIVES
The aluminum alkyls are used by the chemical industry
primarily as polymerization cata-
lysts, one of which is a mixture of titanium(IV) chloride and an

11. aluminum alkyl. It is
called a Ziegler-Natta catalyst, after Karl Ziegler and Giulio
Natta, the chemists who
first discovered its catalytic capability. Aluminum alkyl halides
and aluminum alkyl
hydrides are also primarily used as catalysts in the chemical
industry.
Aluminum alkyl compounds have also been used by the
military, albeit rarely, as
incendiary agents. For example, triethylaluminum has been used
as the active component
in flamethrowers. Trimethylaluminum has also been used to
produce luminous trails in
the upper atmosphere for tracking the location of rockets.
Physical Properties of an Aluminum Alkyl Compound
TABLE 9.G and Two Metal Alkyl Derivatives
Melting point
Boiling point
Specific gravity
Vapor pressure
Flashpoint
Autoignition
temperature
'At 3 mmHg (0.3 kPa).
bAt 68'F (20'C).
'At 77'F (25'C).
TRIETHYLALUMINUM
-62°F (-52°C)

12. 367°F (186°C)
0.837b
0.0147 mmHgb
-63°F (-53°C)
Spontaneously
flammable in air
DIETHYLALUMINUM DIISOBUTYLALUMINUM
CHLORIDE HYDRIDE
-121 °F (-85°C) -112°F (-80°C)
417°F (214°C) 237°F (114°C)a
0.961' 0.798'
0.17 mmHg'
-9.4°F (-23°C)
Spontaneously Spontaneously
flammable in air flammable in air
Triethyl-
aluminum
Ziegler-Natta catalyst
Any of a group of
compounds produced
from titanium
tetrachloride and an

13. aluminum alkyl
compound that is used
mainly as a catalyst
Chapter 9 Chemistry of Some Water- and Air-Reactive
Substances 325
I /I
: I
I I I I I
I/ I I Ill
i I
I I
111 I
I
I I
9 .4-B PROPERTIES OF THE ALUMINUM ALKYL
COMPOUNos A
THEIR DERIVATIVES "'~[)
The aluminum alkyl compounds and their derivatives are
spontaneous!
b_le, pyrophoric, violently water-reactive, and highly toxic
liquids. They y cornbllsr
cially available as individual compounds and solutions in which
they are~~ comm/
organic solvents. When triethylaluminum, diethylaluminum
chloride, and ~~~0 lved t'
aluminum hydride spontaneously ignite, their combustion

14. reactions are re lisobllty~
as follows: Presented
2(C2H5)3Al(l) + 2102(g) Al203(s) + 12C02(g) + 15H20(g)
Triethylalurninum (TEA) Oxygen Aluminum oxide Carbon
dioxide Water
2(C2HshAICl(l) + 1402(g) Al203(s) + 8C02(g) + 9H20(g) +
2BC!(g)
Diethylaluminurn chloride (DEAC) Oxygen Aluminum oxide
Carbon dioxide Water Hydrogen chloride
2 [(CH3)iCHCH2hAIH(s) + 2702(g) Al203(s) + · I6C02(g) +
19H20 (g)
Diisobutylaluminum hydride (DlBAH) Oxygen Al uminum
oxide Carbon dioxide Water
When triethylaluminum and diethylaluminum chlor~de react
with water, the fl
mable gas ethane (Section 12.2) is produced as a hydrolysis
product. a111•
Triethylaluminum (TEA) Water Aluminum hydroxide Ethane
Diethylaluminum chloride (DEAC) Water Aluminum hydroxide
Ethane Hydrogen chloride
Diisobutylaluminum hydride, however, is a reducing agent.
When it reacts with water, the
flammable gases isobutene and hydrogen are produced.
Diisobutylaluminum hydride (DIBAH) Oxygen Aluminum
hydroxide Isobutene Hydrogen
When water is applied to these reactive substances, the gaseous
hydrolysis prod-

15. ucts immediately burst into flame as they are generated. The
considerable heat evolved
to the environment often triggers secondary fires. Bulk
quantities of aluminum alkyl
compounds burn so vigorously and persistently that they pose
an especially dangerous
risk of fire and explosion. The heat of combustion that evolves
necessitates that fire-
fighters wear special protective gear like the silvers shown in
Figure 9.4 when combat·
ing these fires. .
To prevent their accidental ignition, the aluminum alkyl
compounds and their halide
and hydride derivatives often are stored within electrically
grounded containers under an
atmosphere of nitrogen in a cool, well-ventilated area.
9.4-C TRANSPORTING ALUMINUM ALKYL COMPOUNDS
AND THEIR DERIVATIVES
When shippers offer an aluminum alkyl compound or a halide or
hydride derivative for tr:·
portation, DOT requires them_ to id~ntify it with the proper
shipping ~ame, "organomet F.R~
substance," on the accompanymg shipper paper. The Hazardous
Materials Table at 49 C. .
§172.101 lists several shipping names for organometallic
substances. Because triethylal~:
num is both water- and air-reactive, its most appropriate
shipping description is the followmg.
UN3394, Organometallic substance, liquid, pyrophoric, water-
reactive (triethyl-
aluminum), 4.2, (4.3), PG I (Dangerous When Wet).

16. 326 Chapter 9 Chemistry of Some Water- and Air-Reactive
Substances
FIGURE 9 .4 When responding to fires involving
aluminum alkyl compounds and their halide and .
hydride derivatives, firefighters should wear special
protective clothing such as alum1nized suits tha:
reflect heat and provide protection against bodily
contact with the reactive substances as they burn .
(Courtesy of Lakeland Industries, Inc., Ronkonkoma, New
York; Image © 2012, All Rights Reserved.)
FIGURE 9.5 When a carrier transports an alumi-
num alkyl compound or its halide or hydride deriva-
tive in an amount exceeding 1001 pounds (454 kg),
DOT requires SPONTANEOUSLY COMBUSTIBLE and
DANGEROUS WHEN WET placards to be displayed
on the transport vehicle . AKZX is the reporting
mark of AKZO Nobel Chemicals, Inc., Chicago, Illi -
nois, a distributor of triethylaluminum and other
class 4 compounds.
When transporting aluminum alkyl compounds or their halide or
hydride derivatives,
shippers and carriers must also comply with all applicable
labeling, marking, and placard-
ing requirements. Figure 9 .5 illustrates that DOT requires
carriers to display DANGER-
OUS WHEN WET placards on the bulk packaging used for
shipment regardless of the
amount transported.
When 387 gallons (829 L) of liquid diisobutylaluminum hydride
is transported in a 400-gallon (857-L) portable

17. tank by highway:
(a) What sh ipping description does DOT require the shipper to
enter on the accompanying shipping paper?
(b) How does DOT require the carrier to placard and mark the
tank?
Solution
:
(a) There are two regulations in Table 6.2 that are pertinent to
preparing the shipping description . First,
when a hazardous material is described with a generic
description in the Hazardous Materials Table
shippers must include the name of the substance in parentheses
in the shipping description . Second:
when a hazardous material, by chemical interact ion with water,
is liable to become spontaneously
Chapter 9 Chemistry of Some Water- and Air-Reactive
Substances 327

18. ionic A
compound composed
of a metallic ion and a
simple or complex
hydride ion
Sodium hydride
flammable or give off flammable gases in dangerous quantities,
the _w~rds "Dangerous Wh
must be included with the shipping description. Consequently,
the shipping description of d" en 'Net•
luminum hydride is entered on a shipping paper as follows:
iisobu~la.
SHIPPING DESCRIPTION
(IDENTIFICATION NUMBER, PROPER SHIPPING NAME,
PRIMARY HAZARD CLASS OR DIVISION, SUBSIDIARY
VOLU••,
_ _:_U::_N.::_IT:_:S:_--1-_.:_H::.:M~___:_::HAZ~
A_R_D_C_LA_S_S_O_R_D-:-IV_I_SI_O--::N,_A-:-:N_D_P_A-
;-C-:K_IN_G_G_R_O_UP...:...)-+- (gal)'
1 portable tank x UN3394, Organometallic substance, liquid,
pyrophoric, water-reactive 387 (diisobutylaluminum hydride),

19. 4.2, (4.3), PG I (Dangerous When Wet)
(b) Since the amount transported exceeds 1001 pounds, DOT
requires carriers to display side b .
SPONTANEOUSLY COMBUSTIBLE and a DANGEROUS
WHEN WET placard on each side and eac~ side a
the cargo tank. Because the tank has a capacity of less than 1
OOO ~allo~s (3785 L), DOT requires t~: ~:
mark the tank with the identification number 3394 on two
opposing si?es on orange panels, across the
center area of the SPONTANEOUSLY COMBUSTIBLE
placards, or on white square-on-point diamond I ,
9.5 IONIC HYDRIDES
Approximately ten ionic hydrides are encountered commerciall!.
T_hey are compounds
consisting of metallic ions bonded to simple or complex hydnde
ions. Some metallic
hydrides are not ionic hydrides. For example, although tin(IV)
hydride is a metallic
hydride, ·it is composed of molecules. Each molecule consists
of a tin atom covalently
bonded to four hydrogen atoms. Its chemical formula is S~. ·
Ionic hydrides are used as powerful reducing agents by the

20. chemical industry. They
can be classified according to their general chemical
composition as simple ionic hydrides,
ionic borohydrides, and ionic aluminum hydrides.
9.5-A SIMPLE IONIC HYDRIDES
Simple ionic hydrides are compounds consisting of metallic ions
bonded to hydride ions
(H-). They are lithium hydride, sodium hydride, calcium
hydride, magnesium hydride,
and aluminum hydride, whose chemical formulas are LiH, NaH,
CaH2, MgH2, and AlH3,
respectively. They are produced by reactions between the
corresponding metal and hydro-
gen. For example, sodium hydride is a simple ionic hydride
produced by the union of
sodium metal and hydrogen.
2Na(s) + H2(g) 2NaH(s)
Sodium Hydrogen Sodium hydride
9.5-B IONIC BOROHYDRIDES
Ionic borohydrides are ionic hydrides in which metallic ions are
bonded to borohydride
ions (BH4). The commercially important ionic borohydrides are

21. lithium borohydride,
sodium borohydride, and aluminum borohydride, whose
chemical formulas are LiBl-Li,
NaBH4, and Al(B~ h, respectively. The ionic borohydrides are
produced by relatively
complex chemical reactions.
9.5-C IONIC ALUMINUM HYDRIDES
Ionic alu~inu?1 hydrides are ionic hydrides in which metallic
ions are bonded to ahuni·
num hydnde ions (A1H4 ). Two commercially import t · · 1 • h
drides are
1. h' 1 · h d 'd . an tome a ummum y it mm a ummum y n e and
sodium aluminum h d 'd h h . 1 f ulas are . . Y n e, w ose c
emica orm .
L1Al:I4 and NaAlH4, respe~tlvely. They are produced by
reacting the relevant ionic
hydnde and anhydrous aluminum chloride (Section 9.S-A).
328 Chapter 9 Chemistry of Some Water- and Air-Reactive
Substances
,NATER REACTIVITY OF THE IONIC HYDRIDES

22. 9,S·D h the ionic hydrides are relatively stable compounds they
possess several com-
I houg f Of . I · ' At hazardous eatures. specia interest here is
the fact that they react with water to
f!l00 flammable hydrogen.
oduce h . . h . d . pr '[o prevent t e1~ contact wit atmosphenc
moisture, all ionic hydrides are store . m
. hrlY sealed containers. When enc?untered commercially, they
are often covered with
ng I um oil. The presence of the 011 lends an element of safety
when handling and stor-
etrO e h d h . P them- Howeve~, t _ese compoun s_ are also
encountered as ethereal solutions; t _at 1s,
ing are dissolved m diethyl ether, a highly flammable liquid.
The combination of diethyl
and an io~ic hydri~e po~es the risk of fire and explosion. . . .
'[he following equations illustrate the water reactivity of several
representative 1omc
hydrides:
LiH(s) + H20 (/) - LiOH(aq) + H2(g) Lithium hydride Water

23. Lithium hydroxide Hydrogen
3NaBH4(s) + 6H20(I) - 3NaB02(aq) + l 2H2(g) Sodium
borohydride Water Sodium borate Hydrogen
LiAIHi s) + 4H20(l) - Al(OH)3(s) + LiOH(aq) + 4H2(g) Lithium
aluminum hydride Water Alumi num hydroxide Lithium
hydroxide Hydrogen
Al(BH4)3(s) + 12H20( I) - Al(OH)3(s) + 3H3B03(aq) +
12H2(g) Aluminum borohydride Water Aluminum hydroxide
Boric acid Hydrogen
As these ionic hydrides react with water, the evolved hydrogen
absorbs the heat of reaction
and spontaneously bursts into flame.
Because the ionic hydrides are water-reactive substances,
precautions should be exer-
cised to avoid exposing them to humid air or other potential
sources of water. Experts
recommend that firefighters use water as a fire extinguisher
only when they encounter
small spills of these substances.
9.5-E TRANSPORTING IONIC HYDRIDES
When shippers offer an ionic hydride for transportation, DOT
requires them to provide the

24. appropriate shipping description on the accompanying shipping
paper. Table 9.7 provides
TABLE 9.7 Shipping Descriptions of Some Representative Ionic
Hydrides
IONIC HYDRIDE SHIPPING DESCRIPTION
Aluminum borohydride UN2870, Aluminum borohydride, 4.2,
(4.3), PG I (Dangerous When Wet)
or
UN2870, Aluminum borohydride in devices, 4.2, (4.3), PG I
(Dangerous
When Wet)
Calcium hydride UN1404, Calcium hydride, 4.3, PG I
(Dangerous When Wet)
Lithium aluminum hydride UN1410, Lithium aluminum hydride,
4.3, PG I (Dangerous When Wet)
Lithium aluminum hydride
dissolved in ether
UN1411, Lithium aluminum hydride, ethereal, 4.3, (3), PG I
(Dangerous
When Wet)

25. Lithium borohydride UN1413, Lithium borohydride, 4.3, PG I
(Dangerous When Wet)
Lithium hydride UN1414, Lithium hydride, 4.3, PG I
(Dangerous When Wet)
Sodium aluminum hydride UN2835, Sodium aluminum hydride,
4.3, PG II (Dangerous When Wet)
Sodium borohydride UN1426, Sodium borohydride, 4.3, PG I
(Dangerous When Wet)
Sod ium hydride UN1427, Sodium h dride, 4.3, PG I (Dan erous
When Wet y g
Sodium borohydride
Lithium aluminum
hydride
Chapter 9 Chemistry of Some Wate r- and Air-Reactive
Substances 329
metallic phosphide
• An inorganic
compound composed

26. of metallic and
phosphide ions
Calcium
phosphide
some representative examples. When the shipping description is
not listed at 49 C
§ 172.101, DOT requires them to identify the commodity
generically and include th •P.R.
of the specific compound parenthetically. DOT also requires
shippers and carriers t: nallle
ply with all applicable labeling, marking, and placarding
requirements. coll).
9.6 METALLIC PHOSPHIDES
Metallic phosphides are produced by combination reactions in
which a given metal u .
with elemental phosphorus. Calcium phosphide, for example, is
formed by heatingnitels
. d h h ca. c1um an p osp orus.
Calcium Phosphorus Calcium phosphide
These compounds once were popular fumigants used on grain

27. and other postharve
crops, but in the United States, their use is not nearly as po~ular
?ow as it was in the pas:'.
The metallic phosphides function as fumigants by reacting with
atmospheric moisture
to produce the toxic gas phosphine.
Ca3P2(s) + 6H20(l) 3Ca(OH)2(s) + 2PH3(g)
Calcium phosphide Water Calcium hydroxide Phosphine
When calcium phosphide is applied within an enclosure used for
the storage of crops, it~
the phosphine produced by hydrolysis that actually kills mice
and other unwanted pests.
9.6-A TRANSPORTING METALLIC PHOSPHIDES
When shippers offer a metallic phosphide for transportation,
DOT requires them to iden-
tify the appropriate material on the accompanying shipping
paper. Some examples of the
shipping descriptions for several representative metallic
phosphides are listed in Table 9.8.
DOT also requires shippers and carriers to comply with all
applicable labeling, marking, '

28. and placarding requirements.
SOLVED EXERCISE 9.3
What is the most likely reason that DOT requires shippers to
affix DANGEROUS WHEN WET and POISON labels to
packages of stannic phosphide?