Which of the following is the correct formula for copper (I) sulfate trihydrate?

CuSO4 · 3H2O

CuSO4 (H2O) 3

Cu2SO4 (H2O) 3

Cu2SO4 · 3H2O

CuSO₄ · 3H₂O

Explanation:

Sulfate, SO₄²⁻, has a charge of - 2, while copper (I) has a charge of + 1. For the charges to cancel and produce a neutral salt, there must be two copper (I) ions for every sulfate.

The copper (I) sulfate salt may absorb water from its environment to produce a hydrate. The water molecules can usually be removed from the salt by heating and are not bonded directly to the copper (I) ion, but instead are included in the lattice structure of the salt.

The number of water molecules per unit of the salt is indicated and written after the formula for the salt, separated by a dot.

The formula CuSO₄ (H₂O) ₃ indicates that the water is bonded directly to the copper (I) and is not a hydrate.

CuSO4 (H2O) 3 is the correct answer for your question.