Halogen acids strength
When halogen elements
are reacts with hydrogen gas, the compound produce, are known as halogen
acids or halogen hydracids with general formula HX.
There are four halogen acids or hydracids are known which are, hydrofluoric acid ( HF ), hydrochloric acid (HCl),
hydrobromic acid ( HBr ) and hydro iodic acid (HI).
The acidic strength of halogen acid depends on the degree of ionization in aqueous solution as well as bond dissociation energy of halogen acid.
Generally, the degree of dissociation decreases with increasing bond dissociation energy.That is with increasing bond dissociation enthalpy, acidic strength decreases.
Since, the order of bond dissociation energy of halogen acids are, HI < HBr < HCl < HF.Therefore, the increasing acidic order of the above halogen acids are,
HF < HCl < HBr < HI .
Addition of
halogen acids to alkenes
Owing to the
presence of a double bond, the alkenes undergo a large number of addition
reactions. But, under special conditions, they also undergo substitution reaction.
The high
reactivity of the alkenes are due to
presence of pi-bond, that is, due to
presence of loosely bounded olefinic bond electrons.
