Molal Volume
NO.
Nomographs for
I '1
n
I
1-/o
t
5-10
3
6-10
4 5
7-9 5-9 7-10
6-9 8-10
Aliphatic
7-10 8-10 7-8 2-6
Hydrocarbons
2'8
Norma/ olKunes 2Methyl 3 3- ftny/ 2,2-Dlmethyl 2,Z''' 2,32.3'*
-
-
..
-
33-
"
2,2,2'-Trlmethyl
&2,3-
ea
*
Alkenes /norma/)
I1-
Alkynes
*
NO
D. S. DAVIS Wayne University, Detroit, Mich.
F
OLLOWING a study of the molal volume relations of aliphatic hydrocarbons a t their boiling points, Egloff and Kuderl presented the equations : V = ~ ( n 4.4)" - 37.00 (1 ) log (V 37.00) = At B' (2)
+
+
+
1 Egloff, Gustav, and Kuder, R. C., J. P h f f s . Chem., 46 836 (1941).
FIGURE 2
No. n
-9j
2-/o
2
5-/O 6-/O 7-9 6-9
3fthyJ 2 , z - Dimethyl
6-9
2,3-
3 4 5
-50
Norma/ a~'Kanes
1
2- Methy/ 3" 1,
"
7 /O 13
7-/O
3>3-
3-6
I-
AtKenes (normal)
/4
5-8
I-
AlKyneS
e
eB
NO
---.
50
i
.-
--.
.lu*
/5
IB
FIGURE 1 351
i
250
200
where V = molal volume of liquid, ml. n = number of carbon atoms in moolecule t = temperature at boiling point, C. In these equations a is characteristic of the branching, B' depends upon the series, and c and A are characteristic of the unsaturation. The published values of the constants enabled construction of the two line coordinate charts. Figure 1, based upon Equation 1, holds closely for sixty-three aliphatics of the series and ranges of n indicated in the legend; Figure 2, predicated upon Equation 2, covers forty-three of these compounds reliably. The index line in Figure 1 shows that the molal volume of liquid pentyne ( n = 5) is 100 ml. a t the boiling point, while the index line in Figure 2 shows that the molal volume of liquid pentyne (boiling point, 40" C.) is 101 ml. at the boiling point, The standard deviations range from 0.2 to 1.1ml. per mole; Figure 1yields slightly better values than Figure 2 since, as pointed out by Egloff and Kuder, Equation 1 is a function of n, a pure number, while Equation 2 depends upon experimental boiling points.
