Question

What happens when zinc, iodine and acidified water are mixed? Is there a reaction? If a reaction does take place, will the chemical and physical properties of the new substance be the same or different from iodine and zinc?

Answer 1

What happens when zinc, iodine and acidified water are mixed? Is there a reaction? If a reaction does take place, will the chemical and physical properties of the new substance be the same or different from iodine and zinc?

**Answer:**

Zn+I₂ $\xrightarrow{H^+}$ ZnI₂

The appearance of ZnI₂ is white powder different from iodine (dark brown crystals) and zinc (light grey granule or grey powder).

The anhydrous form is white and readily absorbs water from the atmosphere.

The structure of crystalline ZnI₂ is unusual, and while zinc atoms are tetrahedrally coordinated, as in ZnCl₂, groups of four of these tetrahedra share three vertices to form "super-tetrahedra" of composition {Zn₄I₁₀}, which are linked by their vertices to form a three dimensional structure. These "super-tetrahedra" are similar to the P₄O₁₀ structure.

The melting point and boiling point for ZnI₂ are 446 °C and 1150 °C decomp. respectively. ZnI₂ is well soluble in water 450 g/100mL (20 °C), different I₂ weak soluble in water.