Discussion Forum



1)

The correct order of the thermal stability of hydrogen halides (H-X) is


A) HI > HCI < HF > HBr

B) HCl< HF > HBr < HI

C) HF > HCI > HBr > HI

D) HI< HBr > HCI < HF

Answer:

Option C

Explanation:

The H-X bond strength decreases from HF to HI. i.e. HF > HCl > HBr > HI. Thus HF is most stable while HI is least stable. The decreasing stability of the hydrogen halide is also reflected in the values of dissociation energy of the H-X bond

H-F                   H-Cl                  H-Br              H-I

135kcal mol-1 103kcal mol-1  87kcal mol-1   71kcal mol-1