19its a first order reaction , just as we get in haloform reaction !(this one is not haloform, though)
We're looking at the reaction:
RCl + OH- → ROH + Cl- (R being the (CH3)3C-radical)
The reaction is supposed to follow the mechanism:
RCl → R+ + Cl- (k1 forward reaction; k-1 backward reaction)
R+ + OH- → ROH (k2 forward reaction)
The carbonium ion R is at such low concentrations that the steady-state approximation applies. The rate law is then
d[ROH]/dt = k1k2[RCl][OH-]/(k-1[Cl-] + k2[OH-]) (eq. 1)
1st question: Decide if the reaction has a reaction order towards the species RCl, OH- and Cl-. Find the total reaction order, if any.
2nd question: Show that eq. 1 is in fact true.
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6 Answers
19
11The reaction has a reaction order towards R C l
The first step is slow and rate determining step where as step II is fast.
Therefore, r = k1 [R C l ]
106d[ROH]/dt = k1k2[RCl][OH-]/(k-1[Cl-] + k2[OH-])
prove this relation is true...
this is the actual question
anyone?
1For this reaction , when R=C(CH3)3
the OH- does not appear in the rate law,indicating that it must be involved after the rate limiting step .
A possible mechanism will be
(CH3)3CCl → Intermediate
slow
Intermediate +OH- → (CH3)3COH +Cl-
final rate law will be as
rate =k[(CH3)3CCl]
order will be first .
the rate law itself does not prove that this is the correct mechanism because other mechanism would also be consistent with the first order rate law .Moreover the law does not tells us anything about the nature of the intermediate ,other than the fact that it is unstable .
1it is a first order reaction
but the rate law surely gives us the order3
But the equation (i) can be proved by simply solving it using the usual technique