Table 3.

Default physiochemical constants for BTEXN and TPH carbon ranges.

Chemical/Carbon Range 1	Molecular Weight	Vapor Pressure (atms)	Solubility in Water (mg/Lf)	Henry’s Constant (unitless)	Partition Coeff, koc (cm3/g)	Diffusion Coefficient (cm2/s)
						air	water
Benzene	78	0.1	1,790	0.23	146	0.09	1 × 10−5
Ethylbenzene	106	0.01	169	0.32	446	0.068	8.5 × 10−6
Toluene	92	0.04	526	0.27	234	0.078	9.2 × 10−6
Xylenes	106	0.01	161	0.29	375	0.068	8.4 × 10−6
Naphthalene	128	1.0 × 10−4	30	0.018	1,540	0.06	8.4 × 10−6
C5-C8 Aliphatics	93	0.1	11	54	2,265	0.08	1 × 10−5
C9-C12 Aliphatics	149	8.7 × 10−4	0.07	65	150,000	0.07	1 × 10−5
C13-C18 Aliphatics	170	1.4 × 10−4	3.5 × 10−4	69	680,000	0.07	5.0 × 10−6
C19-C36 Aliphatics	280	1.1 × 10−6	1.5 × 10−6	110	4.0 × 10−8
C9-C10 Aromatics	120	2.9 × 10−3	51	0.33	1,778	0.07	1 × 10−5
C11-C22 Aromatics	150	3.2 × 10−5	5.8	0.03	5,000	0.06	1 × 10−5

¹ Constants for BTEXN from USEPA RSL guidance [22]; vapor pressures from TOXNET [27]; Carbon range values from Massachusetts DEP [2] except C13-C18 Aliphatics (based on EC > 12–16) and C19-C36 Aliphatics (based on EC > 16–35 aliphatics) [20].