TABLE 2-1 Physical and Chemical Properties of Some Toxicologically Relevant Mercury Compounds

Chemical Name

Elemental Mercurya

Mercuric Chloride

Mercurous Chlorideb

Methylmercuric Chloridec

Dimethylmercury

Molecular formula

Hg0

HgCl2

Hg2Cl2

CH3HgCl

C2H6Hg

Molecular structure

 

Cl-Hg-Cl

Cl-Hg-Hg-Cl

CH3-Hg-Cl

CH3-Hg-CH3

Molecular weight

200.59

271.52

472.09

251.1

230.66

Solubility

5.6 × 10-5 g/L at 25°C

69 g/L at 20°C

2.0 × 10-3 g/L at 25°C

0.100 g/L at 21°C

1 g/L at 21°C

Density

13.534 g/cm3 at 25°C

5.4 g/cm3 at 25°C

7.15 g/cm3 at 19°C

4.06 g/cm3 at 20°C

3.1874 g/cm3 at 20°C

Oxidation state

+1, +2

+2

+1

+2

+2

aAlso known as metallic mercury.

bAlso known as calomel.

cMethylmercuric chloride is used experimentally to investigate the effects of methylmercury.

tion on some toxicologically relevant Hg compounds discussed later in this chapter.

At 25° C, elemental Hg has a water solubility of 5.6×10-5 g/L. Mercuric chloride is considerably more soluble, having a solubility of 69 g/L at 20° C. In comparison, an organic Hg compound, such as methylmercury chloride, is much less water soluble, having a solubility of 0.100 g/L at 21° C. Dimethylmercury, a very toxic by-product of the chemical synthesis of MeHg (Nierenberg et al. 1998), also has a relatively low water solubility (1.0 g/L at 21° C). Due to its low water solubility, MeHg chloride is considered to be relatively lipid soluble. As discussed later in this chapter, the solubility of the different forms of Hg might play a role in their differential toxicity.



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