SODIUM CARBONATE-SULFATE-HYDROXIDE-WATER 1789
Sept., 1946 AKEAS O F
TABLE I METHOD O F HARKINS AND JURA TELLER= Areas in square meters per gram
SOLIDS CALCULATED BY THE N E W
AND BY
THAT O F BRUNAUER, EMMETT AND
- - ~ - ~
.--New NZ
method of Harkins and Jura-----. :z-Bun-HepHzO tane tanr
Nz r =
lG.l
HzO 14 8
B. E . T . method----11-BuHz0 tane 11.3
T,G.(i
..-
~
-.
-_
ii-Iiep.
tane 61 0
Ti& (Standard) 13.8 13.8 13.8 13.8 13.8 13.8 10.5 13.8 13.8 Ti02I1 8.7 8.4 8.7 8.6 11.7 8.8 8.7 S O l (Quartz) 3.2 3.3 3.3 3.2 4.2 3.2 3 . ti Bas04 2.4 2.3 2.2 2.3 2.4 2.8 2.1 2.7 2.4 ZrSiOr 2.9 2.7 2.8 3.5 2.7 T i 0 2 AI?O? 9.6 11.8 9.5 12.5 9.5 Thjs is Table 111 of the paper by Harkins and Jura (ref. 3) with, a column of calculations for the areas by B.E.T. method using water isotherms with an assumed cross-section of 11.3-4.*for the water molecule.
+
Harkin: and Jura plots where cross-sectional areas (in sq. A. per molecule) of 14.8 for water; 56.6 for n-butane; and 64 for n-heptane are arbitrarily a:signed. However, an assignment of 11.3 sq. A. to water in place of 14.8 gives, as shown in Table I, substantially as good average agreement as obtained by Harkins and Jura, there being only one serious discrepancy in each comparison. Nevertheless, one gets such good agreement only by assigning values of 11.3,56.6 and (34, for water, n-butape and n-heptane, rather than 10.3, 32 and 45 sq. A, that one would calculate from the density of the liquids in the prescribed manner. It, therefore, seems that the cross-sectional areas that have to be assigned to adsorbate niolecules t o obtain are;ts agreeing with those calculated from nitrogen isotherms are sometimes larger than those calculated fro:m liquid densities by factors of as much as 1.5. This is consistent with the results reported by 13eebe, Beckwith and Horiig's who found that values of about 19.5 sq. A. had to be assigned to krypto1l ItIolecules in 1IleaSurementS a t - 1950 t,o obtain surface area \Talues on ;i variety of adsorbents in agreetnerlt with those gotten fro111 (13) I k r , e .
Ilcck\rith
,iiiii
II
