Question

Are SN1 reactions faster than SN2?

Answer 1

There are cases for this answer..!!

Explanation:

SN1 will be faster if:

1.Reagent is weak base.

2.C connected to the Leaving Group is tertiary (sometimes
secondary) i.e. the leaving group must be a better
leaving group. the leaving ability is inversely proportional to
the bacisity of the compound (its basic character

3.The solvent used is polar protic (water and alcohols, etc.)

SN2 will be faster if:
1..Reagent is a strong base.

 2.C connected to the LG is primary or a methyl group                         
    (sometimes secondary)

 3.The solvent used is polar aprotic (DMF, DMSO, etc.)

  4. SN2 reactions need space to inter into the molecule and to
     push the leaving group that's why the molecule must not be
      bulky.