chapter one the estimation of physical properties

PURE COMPONENT CONSTANTS
2.28 CHAPTER TWO
T 102.425 ln N (tƒp1k) W M (tƒp2j ) (2-4.3)
ƒp k j
k
j
T 204.359 ln N (tb1k) W M (tb2j ) (2-4.4)
b k j
k
j
The group values tƒp1k, tƒp2j, tb1k, and tb2j for Eqs. (2-4.3) and (2-4.4) are given
in Appendix Tables C-2 and C-3 with sample assignments shown in Table C-4.
Examples 2-11 and 2-12 illustrate this method.
Example 2-11 Estimate T ƒp and T b for 2,4-dimethylphenol using Constantinou and
Gani’s group method.
solution The First-Order groups for 2,4-dimethylphenol are three ACH, two ACCH 3 ,
and one ACOH. There are no Second-Order groups so the First Order and Second
Order calculations are the same. From Appendix Tables C2 and C3
Group k N k N k tƒp1k N ik tb1k
ACH 3 4.4007 2.7891
ACCH 3 2 3.7270 3.9338
ACOH 1 13.7349 4.4014
5
k1
N k F k
21.8626 11.1243
T
ƒp
102.425 ln (21.8626) 315.96 K
T 204.359 ln (11.1243) 492.33 K
b
Appendix A values for these properties are T ƒp 297.68K and T b 484.09 K. Thus
the differences are
T Difference 297.68 315.96 18.28 K or 6.1%
ƒp
T
b
Difference 484.09 492.33 8.24 K or 1.7%
Example 2-12 Estimate T ƒp , and T b for five cycloalkanes with formula C 7 H 14 using
Constantinou and Gani’s group method.
solution
The First- and Second-Order groups for the cycloalkanes are:
cycloheptane
methyl
cyclohexane
ethyl
cyclopentane
cis-1,3-
dimethyl
cyclopentane
trans-1,3-
dimethyl
cyclopentane
First-Order
groups, N k
CH 3 0 1 1 2 2
CH 2 7 5 5 3 3
CH 0 1 1 2 2
Second-Order
groups, M j
7-ring 1 0 0 0 0
6-ring 0 1 0 0 0
5-ring 0 0 1 1 1
Alicyclic
Side Chain
0 1 1 0 0
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