The depression of freezing point in very dilute aqueous solutions

• Published in: Proceedings of the Royal Society of London. Series A, Containing papers of a mathematical and physical character Containing papers of a mathematical and physical character, 1910-04, Vol.83 (565), p.454-461
• Main Author: Bedford, T. G.
• Format: Article
• Language: English
• Subjects: Conductivity; Ethers; Freezing; Ice; Ions; Melting points; Molecules; Platinum; Potassium; Salts
• ISSN: 0950-1207; 2053-9150
• DOI: 10.1098/rspa.1910.0034

1. According to the ionisation theory, both the depression of the freezing point and the conductivity of a solution of an electrolyte are connected with the ionisation of the solute, and conclusions as to the degree of ionisation in dilute solutions may be drawn from both phenomena, on certain assumptions. The experiments on the depression of the freezing point of very dilute solutions, described in the paper, were planned in connexion with measurements of the conductivity of similar solutions which were made by Mr. W. C. D. Whetham, F. R. S., and have been described in papers communicated to the Royal Society in 1900 and 1902. It was intended to compare the conclusions, drawn from the results of the associated researches, as to the degree of ionisation of the solutions, especially at great dilution. If it be assumed that each molecule which dissociates in solution yields i ions, and that the osmotic pressure is equal to the pressure, according to the simple laws of gases, existing in a gas having the same number of molecules per unit volume as there are molecules and ions in unit volume of the solution, then the coefficient of ionisation (the proportion of molecules ionised in the solution) is given by α = ∆δ/δ(i-1).