Non-isothermal dehydration of copper chloride dihydrate and nickel chloride hexahydrate were studied by using TG, DTG, DTA
and DSC measurements. The copper chloride salt loses its two water molecules in one step while nickel chloride salt dehydrates
in three consecutive steps. The first two steps involve the loss of 4 water molecules in two overlapped steps while the third
step involves the dehydration of the dihydrate salt to give the anhydrous NiCl2.
Activation energies (ΔE) and the frequency factor (A) were calculated from DTG and DTA results. We have also calculated the different thermodynamic parameters, e.g. enthalpy
change (ΔH), heat capacity (Cp) and the entropy change (ΔS) from DSC measurements for both reactants.
The isothermal rehydration of the completely dehydrated salts was studied in air and under saturated vapour pressure of water.
Anhydrous nickel chloride was found to rehydrate in three consecutive steps while the copper salt rehydrated in one step.