Question

Acidity of diprotic acids in aqueous solutions increases in the order:

• A. H₂Se < H₂S < H₂Te
• B. H₂Te < H₂S < H₂Se
• C. H₂Se < H₂Te < H₂S
• D. H₂S < H₂Se < H₂Te

Answer 1

The Correct Option is D

The given problem asks us to determine the order of acidity for the diprotic acids: H₂S, H₂Se, and H₂Te. The acidity of these acids is dependent on the stability of the anion formed after dissociation and the bond strength between hydrogen and the respective non-metal (S, Se, Te).

Here is the step-by-step reasoning:

1. The acidity of hydrides of group 16 elements typically increases down the group. This is because larger atoms have more diffuse orbitals, which leads to weaker H-X bonds, thus making it easier to donate protons.
2. Among H₂S, H₂Se, and H₂Te, the size of the central atom increases from S to Te: S < Se < Te.
3. The larger the atom bonded to hydrogen in a diprotic acid, the weaker the bond due to decreased overlapping of orbitals, making the acid stronger as it can dissociate more easily to release hydrogen ions.
4. Hence, the order of strength of the acids is determined by the ability of the molecule to lose H⁺ ions: \text{H}_2\text{S} < \text{H}_2\text{Se} < \text{H}_2\text{Te}

Thus, the correct order of increasing acidity for these compounds is given by the option H₂S < H₂Se < H₂Te.