Question

arrange the following : HCl,HBr,HI and HF in order of their decreasing reactivity towards alkene

Answer 1

HI>HBr>HCl>HF.........

Answer 2

Explanation:

All F, Cl, Br, and I atoms belongs to the same group. It is known that down the group there is increase in the size of atoms. Thus, fluorine will be smaller in size and iodine will be largest in size.

Therefore, as the size of anion increases there will be increase in the bond length of acid as the cation is same in all the cases given here.

As a result, energy required to break the bond length will decrease with increase in the size of anion. As a result, ionization will increase which will further increase the reactivity.

Thus, we can conclude that decreasing reactivity towards alkene will be in the order HI > HBr > HCl > HF.