J.H. van ’t Hoffs theorie van de vaste oplossingen (1890)

Abstract

J.H. van 't Hoff’s theory of solid solutions (1890) Jacobus Henricus van 't Hoff’s theory of diluted solutions (1886), which was based on the analogy between solutions and gases, made it possible to determine molecular weights of substances in solution. A number of chemists however (a.o. J.F. Eykman and E. Paterno) found deviations from Van 't Hoffs theory for the depression of the freezing point by dissolved substances. In all cases, the depression was too small. To explain these irregularities Van 't Hoff published a theoretical article: "Ueber feste Losungen und Molekulargewichtsbestimmung an festen Korpern" (1890). In it he assumed that the dissolved substance crystallized out along with the solid solvent. The homogeneous mixed crystals thus obtained, which Van "t HotT called dilute solid solutions, showed a great resemblance in their behaviour to ordinary liquid solutions. Therefore they obeyed the laws applicable to diluted solutions, (the theory was experimentally verified by Van 't Hoffs student Albert van Bijlert.) It was Van 't Hoffs successor in Amsterdam, Hendrik Willem Bakhuis Roozeboom, who incorporated the solid solutions in his phase theory. He treated them theoretically in an article on the "Erstarrungspunkte der Mischkrystalle zweier Stoffe" and had it experimentally verified by a number of his graduate students.