l h e parameters usually irivoked to explain the teiiiperature am1 concentration variation of riiffusioii are the viscosity arid the activity. I'licw f ,Ic*tors are coupled in the cxliression16
With tlie viscosity data o f Binghani arid Whitelx cJthers19~20 the first factor givrs computed ralues of the diffusivity (1)) iiiuch lower than those observed, and the second activity factor" ylevates these values only slightly, t ( J within only a third to ;I fifth of the :~ctuallyobserved values. This saiiie situation obtains in dilute sucrose solutions but to a lcss magnified exteiit." Apparently soiiic. factor is oper;Ltiiig which has a inore proriouncetf effect upon viscosity than upon diffusion.& A (hydrogen bonded) 1i cluster of sucrose molecules miglit offer tremendous fluid resistance to rnoveiiient through a medium, and yet lose or exchange its in~livid~ial niembers quite freely in diffusion. aiitl
1
L'
I
i
IV.
Summary
'l'hc. diffusioti covtricieiits oi aqueous sucrose SOI u t i i I I I S tiiniiiiish litiearly frc'miconcentrations above I J I I V niolar to a t least the saturation concentration. 'l'lit~Stctkes--Bilist.eiri inzplicatioii of ari inverse
clit~usivjty-visct,sity relation is elltirely iiiackqu;r te to cxplain the results obtained. IMTusioii cocflicierits of U. 1 .M potassiurn chloride exhibit a slight coiivexity on the usual semilogarithinic-reciprocal temperature plot,
I
A. I<
