When copper(II) sulfate pentahydrate (CuSO₄·5H₂O) is heated, it undergoes a series of dehydration reactions, losing its water molecules one by one. Here's a breakdown of the process:

1. Initial Dehydration (Low Heat):

* Reaction: CuSO₄·5H₂O(s) → CuSO₄·H₂O(s) + 4H₂O(g)

* Observation: The blue crystals of copper(II) sulfate pentahydrate will start to turn white or pale blue as water molecules are released.

2. Further Dehydration (Moderate Heat):

* Reaction: CuSO₄·H₂O(s) → CuSO₄(s) + H₂O(g)

* Observation: The white or pale blue solid will become completely white as the remaining water molecule is lost.

3. Anhydrous Copper(II) Sulfate (High Heat):

* Reaction: CuSO₄(s) → No further reaction at this stage.

* Observation: The white anhydrous copper(II) sulfate (CuSO₄) remains stable at this temperature.

Important Notes:

* The exact temperature at which each dehydration step occurs can vary depending on the heating rate and conditions.

* The anhydrous copper(II) sulfate is hygroscopic, meaning it readily absorbs water from the air, turning back into the blue pentahydrate form.

Uses of Anhydrous Copper(II) Sulfate:

* Water Detection: Anhydrous copper(II) sulfate is used as a desiccant (drying agent) because it turns blue when it absorbs water. This property makes it useful for detecting moisture.

* Fungicide: It is also used as a fungicide in agriculture.

Overall, the heating of copper(II) sulfate pentahydrate is a good example of a dehydration reaction where water molecules are removed from a hydrated compound.