Diffusivity of ammonium dihydrogen phosphate in aqueous solutions

Empirical relationships commonly used for the prediction of liquid diffusivity data are shown to be unreliable for aqueous solutions of solid solutes. An interferometric technique suitable for diffusivity measurement in such solutions is described. For the system ammonium dihydrogen phosphate‐water over the temperature range 15–50° diffusivities can be estimated from the relationship Dζ × 108 = 4.7 + 0.16θ The activation energy for diffusion in near‐saturated solutions over this temperature range is ∼10 kcal./mole.