Question

How does temperature affect SN1 reactions?

Answer 1

A rise in temperature should accelerate a bond-breaking reaction......

Explanation:

Of course, temperature increase generally increases the rate of most chemical reactions, however, for a typical `S_N1` reaction, we may invoke the following elemental step:

`RCH(X)R'rightleftharpoonsRC^+HR' +X^-`

And this is the rate determining step of the reaction.........

And because this, the rate determining step, involves BOND-BREAKING, we would predict that an increase in temperature should result in the production of more `RC^+HR` species, and thus an INCREASE in the rate of reaction..........

Another way to look at this is to include heat, i.e. `Delta`, as a virtual reactant.............

`RCH(X)R' +DeltarightleftharpoonsRC^+HR' +X^-`

If we raise the temperature, we supply `Delta`, and, therefore, we should drive the equilibrium to the RIGHT as shown.