Measurements of equilibrium water vapor pressures for the dehydration of magnesium, manganese and cobalt formate dihydrates by means of the transpiration method

摘要

The equilibrium water vapor pressures for the thermal dehydration of Mg(HCO_2)_2 centre dot 2H_2O, Mn(HCO_2)_2 centre dot 2H_2O and Co(HCO_2)_2 centre dot 2H_2O were measured by means of the transpiration method. These hydrates form isomorphous crystals with space group P21/c. In this structure, the water molecules lie in the planes parallel to the (100) planes. Thermodynamic data such as ΔG, ΔH and ΔS were derived from the values of the water vapor pressures. The relationship between these thermodynamic data and the crystal structures is discussed.