Mutual-diffusion coefficients and viscosities for the water–2-methylpropan-2-ol system at 15 and 25 °C

Abstract

Mutual-diffusion coefficients have been measured by the Taylor dispersion technique and viscosities by capillary viscometry at 15 and 25 °C for dilute aqueous solutions of 2-methylpropan-2-ol (tert-butyl, alcohol or TBA). Comparison is made with other water–alcohol systems and water–2-butuxyethanol. Ornstein–Zernicke correlation lengths, ξ, for this system are compared with those for mixtures of water with methanol, ethanol, propan-1-ol and butan-1-ol and contrasted with those of systems representative of other classes of non-electrolyte mixtures. ξ for water–propan-1-ol rises to a maximum at a mole fraction (x) of 0.15, suggestive of the long-range correlation of molecular motion in this solution or pseudo-critical behaviour; water–TBA appears to behave similarly with a rapid increase in ξ above x= 0.05.