2462
LEOXARD F. DRUDINC AND Jorriv D. CORBETT 16 14
12
-10 ? i ON I:
-- 8 U
N
I
r 2
..r
-. z
4
Y
-
-a 2
-0 +N
[r
I
~
0
j
1
2 4 6 CHLORiDE CONCN-
+
8 1 0 1 2 1 4 MOLES/ I. x I O 3
Fig. 4.-Plots of (Rz R”)/[Pt(NH&Cl(K~O)+] vs. chloride concentration. Indicated AH” = 20.3 kcal., A S * = -11 e. u.
values of the parameter less than 1.0. In Fig. 4 has been plotted the quantity (& R”)/[Pt(SI-I1)lCI(H20)+] vs. [Cl-] for all cases in which i t W I S calculated Although the values do increase somewhat with [ C Y ] ,it was felt that the increase was not significant in view of the uncertainty in the pxameter a t the higher chloride concentration. I t has been concluded, therefore, that the reaction rate sum (Rl I?”) is substantially 7ero order in chloride. The weighted averages for the indicated first order rate constants ( k , k”), together with
+
+
+
[CONTRIUUTIOS NO.
971
Vol.
s::
values for AH* and AS* have been included with the data in Fig. 4. I t has not been possible to separate the individual reaction rates R,and R”. Since reaction 12, with the rate R”,is chloride independent and is not LL solvation process, it presumably woultl have t C J proceed by a dissociative mechanism. I t is possiblc that the entire exchange is carried by the acid hydrolysis, i.e., k”
