CHEMISTRY: I. LANGMUIR 
257 
number of electrons in each molecule (including those in their kernels) is four- 
teen. Evidence is given in the paper in the Journal of the American Chemical 
Society that the structures of these two molecules is identical, except for the 
fact that in one case there are two nuclei of seven positive charges each, while 
in the other there are nuclei of six and eight charges, respectively. These 
molecules are, however, exceptional, in that the molecule consists of a single 
octet arranged around a complex kernel. 
Another example of a pair of compounds which according to the Octet 
Theor)^ should have similar structures occurs in the case of CO2 and N2O. 
For each of these molecules = 3, e = 16 and therefore p = A. The best 
method of testing this conclusion lies in comparing the 'physical' properties of 
the two substances. The 'chemical' properties depend primarily on the ease 
with which the molecules can be broken up, and thus is a measure of the in- 
ternal forces within the molecule, which depend to a large extent on the charges 
on the kernels. The so-called 'physical' properties on the other hand depend 
on the stray field of force outside of the molecule, and this naturally depends 
rather on the arrangement of the outside electrons. 
As a matter of fact we find that most of the physical properties of these two 
gases are practically identical. 
The following data taken from Landolt-Bornstein tables and Abegg^s 
hand book illustrate this. 
N2O 
CO2 
75 
77 atmos. 
35.4° 
31.9° 
Viscosity at 20°C 
148 X ia-« 
148 X 10^ 
Heat Conductivity at 100°C 
0.0506 
0.0506 
0.996 
1.031 
Density of Liquid at +10° 
0.856 
0.858 
1.193 
1.190 
Dielectric constant of liquid at 0° 
1.598 
1.582 
0.12 X 10-« 
0.12 X 10-* 
Solubility in water 0° 
1.305 
1.780 
3.25 
3.13 
Both gases form hydrates N2O.6H2O and CO2.6H2O. The vapor pressure of 
the hydrate of N2O is 5 atmospheres at — 6°G. while the hydrate of CO2 has 
this vapor pressure at — 9°C. The heats of formation of the two hydrates are 
given respectively as 14,900 and 15,000 calories per gram molecule. 
The surface tension of hquid N2O is 2.9 dynes per cm. at 12. °2, while CO2 
has this same surface tension at 9.0°. 
Thus N2O at any given temperature has properties practically identical 
with those of CO2 at a temperature 3° lower. 
These results estabhsh the similarity of outside structure of the molecules. 
