The electrophilic addition reaction of HBr with propene involves a two-step mechanism. Here's a step-by-step explanation of the mechanism:Step 1: Protonation of the alkene formation of carbocation 1. Propene CH3-CH=CH2 acts as a nucleophile due to the presence of the electron-rich double bond C=C .2. HBr acts as an electrophile because the hydrogen atom H is slightly positive + due to the polar bond between H and Br.3. The electron-rich double bond of propene attacks the slightly positive hydrogen atom of HBr, breaking the H-Br bond and forming a new C-H bond.4. This results in the formation of a carbocation intermediate, as one of the carbon atoms loses its share of electrons from the double bond and becomes positively charged. In this case, a secondary carbocation is formed CH3-CH + -CH3 because it is more stable than the primary carbocation.Step 2: Nucleophilic attack by bromide ion formation of the final product 1. The negatively charged bromide ion Br- that was generated in the first step acts as a nucleophile.2. The bromide ion attacks the positively charged carbon atom of the carbocation intermediate, forming a new C-Br bond.3. The final product is 2-bromopropane CH3-CH Br -CH3 , which is formed through the electrophilic addition of HBr to propene.Overall reaction: CH3-CH=CH2 + HBr CH3-CH Br -CH3