What happens when blue solid CuSO4.5H2O is heated?

When blue solid CuSO4·5H2O is heated, it undergoes a dehydration process where it loses its water of hydration. The blue color is characteristic of the pentahydrate form of copper(II) sulfate, which contains five molecules of water for each molecule of CuSO4. Upon heating, the water molecules are released as vapor, leading to a significant change in the compound's appearance and properties.

As the water is removed, the hydrated copper(II) sulfate transitions to anhydrous copper(II) sulfate, which is white in color. This distinctive color change from blue to white serves as a clear visual indication that the hydration water has been effectively evaporated. Thus, observing this transformation provides evidence of the fundamental changes in the chemical structure as the compound loses its water content.

This process is a common demonstration in chemistry to illustrate concepts of hydration and dehydration. Understanding this transition can be helpful for chemists in practical laboratory settings when dealing with hydration states of substances and their subsequent thermal behavior.