Why when copper sulphate crystals are placed in water it dissolved?

Question

Why when copper sulphate crystals are placed in water it dissolved?

Answer 1

Copper sulphate crystals has a lattice.

Lattice is a three dimentional regular arrangements of ions ( or atoms or molecules). When lattice is formed then some energy is released. This energy is called lattice energy and this much energy will be needed to break the lattice.  

When copper sulphate dissolve, the regular arrangement of ions is broken and energy equal to lattice energy will be required to break the lattice.

Copper sulphate crystals in contact with water molecules and there is interaction between the two. Water is polar in nature. Therefore, copper and sulphate ions are attracted to water molecules to form some sort of bonding. There is a release of energy due to inteaction (bonding) between water molecules and copper and sulphate ions. This energy is called hydration energy. The lattice of copper sulphate will break ( dissolves) if hydration energy is more than lattice energy. thus energy required to break lattice is provided by hydration of ions. That is how copper sulphate (or any other water solublesalt) dissoves in water.

Answer 2

because copper sulphate is a salt and more specifically a soluble ionic compound and since it consist of ions in which water molucules are attracted to it the surroumding water molecules will break up the crystal lattice structure.