All of the hydrogen halides (H-X) are gaseous in their natural state, but dissolve in water to form the aqueous phase.
Entropies (S) for the gaseous H-X molecules (before reaction) are:
HCl (g): 186.79 J/mol
HI (g): 206.33 J/mol
Entropies (S) for the H-X molecules dissolved/solvated in water (after reaction) are:
HCl (aq): 143.17 J/mol
HI (aq): 219.8 J/mol
1. Calculate the ΔS that each of these H-X compounds undergoes as it transitions from the gas phase to the aqueous phase.

The ΔS value of HCl undergoing transitions from gas to the aqueous phase is -43.62 J/mol.

The ΔS value of HI undergoing transitions from gas to the aqueous phase is 13.47 J/mol.

Explanation:

Entropy of the reaction :

1) Entropies the gaseous HCl molecules=

Entropies the aqueous HCl molecules=

The ΔS value of HCl undergoing transitions from gas to the aqueous phase is -43.62 J/mol.

2) Entropies the gaseous HI molecules=

Entropies the aqueous HI molecules=

The ΔS value of HI undergoing transitions from gas to the aqueous phase is 13.47 J/mol.

the answer to this question is 3.