Apparent and partial molar volumes of long-chain alkyldimethylbenzylammonium chlorides and bromides in aqueous solutions at T=15 deg. C and T=25 deg. C

Density measurements of dodecyl- (C12DBACl), tetradecyl- (C14DBACl), hexadecyldimethylbenzylammonium chloride (C16DBACl) and of decyl- (C10DBABr) and dodecyldimethylbenzylammonium bromide (C12DBABr) in aqueous solutions at T=15 deg. C and T=25 deg. C have been carried out. From these results, apparent and partial molar volumes were calculated. Positive deviations from the Debye-Hueckel limiting law provide evidence for limited association at concentrations below the critical micelle concentration. The change of the apparent molar volume upon micellization was calculated. The relevant parameters have been presented in function of the alkyl chain length. Apparent molar volumes of the present compounds in the micellar phase, Vphim, and the change upon micellization, ΔVphim, have been discussed in terms of temperature and type of counterion