Explain why `I_(2)` can displace `Cl_(2)` from `KClO_(3)` but not from KCl.

Explanation

Since chlorine is a much stronger oxidising agent than iodine, it cannot be displaced by iodine from KCl . However, iodine can displace chlorine from `KClO_(3)`.
`I_(2)+KClO_(3)to2KIO_(3)+Cl_(2)`
Iodine is more electropositive than chlorine. In `KClO_(3)` , chlorine exists in oxidised state, i.e., it exists as the positive part. Highly electronegative oxygen atom has greater affinity towards iodine compared to chlorine and wants to place iodine nearby instead of chlorine. Because of this, iodine displaces chlorine from `KClO_(3)`.
[lnfact, the standard reduction potential `(E^(0))` of `ClO_(3)^(-)//1/2Cl^(2)` system (+1.40V) is greater than `IO_(3)^(-)//1/2I_(2)` system (+1.20V) and for this, such an abnormal reaction takes place.]