Why is tertiary carbon atom more reactive towards sn1 reaction even though it is the most stable one??
BECAUSE the formal cation that results from the tertiary carbon is intrinsically the MOST stable...
The fast step is the reaction of some nucleophile,
Now because secondary carbocations are stabilized with respect to methyl, and primary carbocations, and tertiary carbocations are stabilized with respect to secondary carbocations, the order of reactivity in terms of
And this order reflects the stability, the lifetime if you like, of the reactive carbocation intermediate. Sterically encumbered carbocations thus have faster rates of reactions in bond-breaking scenarios.