secondary cells with lithium anodes and immobilized fused_salt

. .- .
- ..... . .
I
,caving the reactor, T is the average residence time in the reactor, and n is the
orOer of the reaction.'
6 plot of ab-cy) vs T, where a is the fraction reacted, should be linear with a
80.
It can be shown from eq 2 that for a first-order reaction,
slope equal to the rate constant. Figure 1 shows that the decomposition of ClF5
follows first-order kinetics up to 80$ reaction at 293O. "he data in Figure 1 were
c'stained at temgeratures of 29l.5-294.Oo, md corrected to 293.0' using an activation
energy of 41 kcal/mole. The rate constant, 1x1 from each experiment is listed
In Table 1. The best first-order rate constant, klA, at each temperature, obtained
fro3 a ?lot of the type shown in Figure 1, is given in the last colm of Table 1
ad plotted in the Arrhenius fonn in Figure 2. A least squares fit of the data to
the Arrhenius expression yields the line shown in Figure 2 which represents the rate
expression:
-1
kl = exp(-41,330/RT) sec (3)
:.e mceytainty in activation energy is about 2 kcal./mole.
n; -,e ~Lxing requirements for a stirred flow reactor do not allow a convenient
3roce5ure for varying widely the surface-to-volume ratio, but the high values of
the activation enera and preexponential factor suggest that the reaction is hao-
geneous in nature.
reactor, containing products of reaction, had been allowed to sit at 280° for 1
Lonth .
21scuss10s
Three possible mechanisms may be written which are compatible with the observed rate
expression, i.e., first order in ClF5 with no apparent inhibition as the products
accwulate :
A) Unimolecular Elimination of F2
ClF5 4 CLF3 + F2
B) Non Chain Radical Mechanism
CLr5 0 CLF4 + F
C1F4 0 ClF3 + F
F + F + M -. F2 + M
C) Long Chain Radical Mechanism
ChF5 - clP4 + F
F + Clr 5 -. ClF4 + F2
CL"4 0 ClF3 + F
F + ClF4 0 CLF3 + F2
Also, it was found that the rates were unchanged after the
"he long chain mechanism (C) may be questioned on the bagis of the observed rate
parameters A and Z. Mechanism (C) requires that
1
A = (!*)+
and E P &(E5 + E6 + ET - E$
?he A factors for the 1-dividp steps can be estimated fran the generalizations
yoposed by Benson aad Demore . nus,
0. S. W. 3,enson anC Y. 3. Sezore, Ann. Rev. Phys. Chem., 16,426 (1965).