posted by mejo .
i nned to know the reason for crystal formation in magnesium sulphate salt.
It is a minimum energy configuration.
The technical answer is that the energy going into the formation of the Mg ion and the SO4 ion is less than the energy of formation of the solid crystal; therefore, the delta H for the entire process is negative and energy is released with the crystal is formed. Look up the Born-Haber cycle for a complete explanation of the process.