TABLE 2-1 Physical Properties of Nerve Agents

Agent Characteristic

GB

VX

Chemical formula

C4H10FO2P

C11H26NO2PS

Molecular weight

140.10

267.38

Boiling point (°C)

150 (extrapolated)

292 (extrapolated)

Freezing point (°C)

−55

≤51

Vapor pressure at 25°C (mm Hg)

2.48

0.000878

Volatility at 25°C (mg/m3)

18,700

12.6

Surface tension at 20°C (dynes/cm)

26.5

32.0

Kinematic viscosity (cSt)

1.28 at 25°C

12.26 at 20°C

Liquid density at 25°C (g/cm3)

1.0887

1.0083

Solubility (g/100 g of distilled water)

100; soluble in organic solvents

5 at 25°C; best solvents are dilute mineral acids

Heat of vaporization (cal/g)

82.9

71.8

Heat of combustion (cal/g)

5,600

8,300

SOURCE: NRC, 2005; Abercrombie, 2003.

TABLE 2-2 Physical Properties of Mustard Agentsa

Agent Characteristic

HD

HTb

Chemical name

Bis (2-chloroethyl) sulfide or 2,2'-dichlorodiethyl sulfide

Same as HD with 20 to 40 wt% agent T, bis[2(2-chlorethylthio) ethyl] ether

Chemical formula

C4H8Cl2S

Not applicable

Molecular weight

159.07

188.96 (based on 60/40 wt%)

Vapor density (relative to air)

5.5 (calculated)

6.5 (calculated based on 60/40 wt%)

Boiling point (°C)

218 (extrapolated)

No constant boiling point

Decomposition temperature (oC)

180

165 to 180

Freezing point (°C)

14.45

1.3 (measured as melting point)

Vapor pressure at 25°C (mm Hg)

0.106

7.7 × 10–2 (calculated based on Raoult’s law equation)

Volatility at 25°C (mg/m3)

9.06 × 102 (calculated from vapor pressure)

7.83 × 102 (calculated from vapor pressure)

Diffusion coefficient for vapor in air (cm2/sec)

0.060 at 20°C (68°F)

0.05 at 25°C (77°F)

Flash point (°C)

105

Flash point range 109 to 115

Surface tension (dynes/cm)

43.2 at 20°C (68°F)

44 at 25°C (77°F)

Viscosity at 20°C (cSt)

3.52

6.05

Liquid density at 25oC (g/cm3)

1.2685

1.263

Solubility (g/100 g of distilled water)

0.092 at 22°C (72°F); soluble in acetone, carbon tetrachloride, chloroform, tetrachloroethane, ethyl benzoate, ether

Slightly soluble in water; soluble in most organic solvents

Heat of vaporization

 

Not available

(Btu/lb)

190

 

(J/g)

82

 

Heat of combustion

 

Not available

(Btu/lb)

8,100

 

(J/g)

3,482

 

aMustard agents are labeled H, HD, and HT. The active ingredient in all these blister agents is bis(2-chloroethyl) sulfide, or (ClCH2CH2)2S. HD, called the distilled mustard, is nominally pure mustard agent. H, often called Levinstein mustard, was approximately 70% pure mustard agent and 30% impurities at the time of manufacture. However, the stored H mustard agent has deteriorated over time and its physical properties are highly variable. H is the only form of mustard agent stored at Blue Grass Army Depot.

bOverall proportional composition of the mixture. HT is prepared by a chemical process that synthesizes the HT directly in such a way that it contains both the HD and T constituents without further formulation.

SOURCES: Adapted from U.S. Army, 1988; Abercrombie, 2003; BPT, 2004.



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