The electrophilic addition of hydrogen bromide HBr to propene is a two-step process involving the formation of a carbocation intermediate. Here's the mechanism:Step 1: Protonation of the alkeneThe alkene propene acts as a nucleophile and attacks the electrophilic hydrogen atom of HBr. This leads to the formation of a carbocation intermediate and a bromide ion Br- . The carbocation can be formed at either the primary or secondary carbon atom, but the more stable carbocation is formed at the secondary carbon due to hyperconjugation.Propene + HBr [CH3-CH + -CH3] + Br-Step 2: Nucleophilic attack by bromide ionThe bromide ion Br- acts as a nucleophile and attacks the carbocation, forming a new C-Br bond. This results in the formation of 2-bromopropane.[CH3-CH + -CH3] + Br- CH3-CHBr-CH3The overall reaction is:Propene + HBr 2-bromopropaneThe electrophilic addition of hydrogen chloride HCl to propene follows a similar mechanism:Step 1: Protonation of the alkenePropene + HCl [CH3-CH + -CH3] + Cl-Step 2: Nucleophilic attack by chloride ion[CH3-CH + -CH3] + Cl- CH3-CHCl-CH3The overall reaction is:Propene + HCl 2-chloropropaneThe main difference between the addition of HBr and HCl to propene is the identity of the halogen atom bromine vs. chlorine and the corresponding halide ions Br- vs. Cl- . Both reactions follow the same mechanism and result in the formation of haloalkanes 2-bromopropane and 2-chloropropane, respectively . However, the reactivity of HBr and HCl may differ due to the difference in bond strength and electronegativity between hydrogen and the halogen atoms. HBr is generally more reactive than HCl in electrophilic addition reactions due to the weaker H-Br bond compared to the H-Cl bond.