Question

The correct increasing order of the stability of the tri halide ions

Answer 1

As we proceed down a coloumn in the periodic table, the Electronegativity of the Atoms of the elements Decreases but the stability of their conjugate bases Increases, which signifies that the Acid strength ( i.e. tendency to donate H+ ions ) increases.

HX + H2O → H3O+ + X-

( X = F, Cl, Br, or I )

Thus,

the relative orders of acidity is:

HI > HBr > HCL > HF

This tells that Hydroiodic acid dissociates fastly in aqueous medium and Hydrofluoric acid least.

the relative stability of the conjugate bases ( or halide ions in aqueous medium ) is:

I- > Br- > Cl- > F-

Furthermore this tells that in Nucleophilic substitution reactions, the Iodide ion will be a Good Leaving group while Fluorine is poor because of its small size and greater electronegativity.

I hope I have helped you :)

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