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Apparent molar heat capacities and volumes of aqueous solutions containing HClO4 and HNO3 have been determined from 10 to 55 °C. The temperature dependences of the standard state heat capacities and volumes of ClO4− (aq) and NO3− (aq) from 10 to 55 °C were found to be well represented by the following equations:[Formula: see text]Combination of the experimental results with semiempirical equations for ion–solvent interaction has led to predictions of the standard state volumes and heat capacities for these ionic species at higher temperatures. Keywords: heat capacities, volumes, nitric acid, perchloric acid.

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Uses of heat capacities of solutions of electrolytes are reviewed, with a particular emphasis on the standard state partial molar heat capacities and their applications to calculations of the effects of temperature on equilibrium constants, electrode potentials, enthalpies, and entropies. Methods of obtaining these standard partial molar heat capacities are summarized, followed by comparisons of values obtained in different ways. Many of the "best" such heat capacities are collected and then used as the basis for establishing single-ion heat capacities based on the convention that c p O (~+ ) = 0, followed by illustrations of the convenient use of these quantities. Finally, there is brief discussion of theoretical analysis of these standard partial molar heat capacities in relation to ion-solvent interactions.Key words: heat capacities, electrolytes; aqueous solutions, heat capacities; thermodynamics, electrolytes.RCsumC : On prksente une revue de l'utilisation des capacitCs calorifiques de solutions d'Clectrolytes en insistant d'une faqon particuliere sur les capacites calorifiques molaires partielles dans 1'Ctat standard et leurs applications aux calculs des effets de la temperature sur les constantes d'equilibre, les potentiels d'klectrode, les enthalpies et les entropies. On rksume les methodes d'obtenir ces capacites calorifiques molaires partielles standard et on prksente ensuite un comparaison des diverses valeurs obtenues d'aprks les diverses manieres. Plusieurs des ccmeilleuresa propriCtCs, comme les capacitks calorifiques, ont CtC rassemblCes et ont ensuite Ct C utilisees comme base pour I'Ctablissement des capacitks calorifiques d'un seul ion en se basant sur la convention que c,' (H+) = 0; elles sont suivies par des illustrations sur l'utilisation commode de ces quantitks. Enfin, on presente une breve discussion de I'analyse thiorique de ces capacitks calorifiques molaires partielles standard en relation avec les interactions ion-solvant.

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