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Three simple cases are discussed, in which adsorption calorimetry provides information about the structure of the adsorbent surface: i) hydrophilicity and hydrophobicity of various SiO 2 ; ii) occurrence of different types of crystal faces on ZnO; iii) state of oxidation of Copper in a Cu/ZnO catalyst.

The decomposition of solid solutions of CaCO 3 -SrCO 3 , covering the whole range of composition, has been studied by simultaneous TG-DTA. In all cases a two-stage decomposition occurs and the presence of strontium stabilizes CaCO 3 . The effect of the different amounts of calcium and strontium ions present in the samples has been separately evaluated by comparison with the results obtained by decomposing mechanical mixtures of CaCO 3 and SrCO 3 of the same composition.

The measurement of the energy of interaction of a molecule with a surface as a function of coverage provides information on the state of the surface and on the thermodynamic characteristics of the adsorption process. Access to Δads H is usually obtained on polycrystalline materials by means of a microcalorimeter connected to a dosing device which enables the simultaneous measurement of small uptakes and related heats. Small increments in the adsorba te from the lowest coverage to saturation can thus be evaluated. Successive adsorption-desorption cycles allow the separation of effects due to reversible and irreversible phenomena. The adsorption of the same adsorptive onto variously pretreated solids or on materials of different origin yield evidence of differences in the state of the surface. The application of this technique in various fields of surface science will be reported and the usefulness of joint use of microcalorimetry with other techniques will be stressed.