Turbidity of deuterated isobutyric acid and heavy water in the one-phase region near the critical solution point

Abstract

We have measured the total light scattered from a mixture of deuterated isobutyric acid and heavy water (deuterium oxide, D2O ) near its upper critical solution point. The resulting turbidity was measured in a reduced temperature region 10−6<t<10−2, where t=(T−Tc)/Tc and Tc is the critical solution temperature, in a sample close to the critical composition. This completely deuterated mixture near its critical point exhibits similar properties to the undeuterated mixture and the turbidity can be explained using an Ising model. When the critical exponents ν and γ were fixed at the values predicted from renormalization-group theory, the amplitude ξ0 of the correlation length was determined to be 0.343±0.024 nm, while the amplitude of the turbidity τ0 was (3.51±0.03)×10−6 cm−1, which seem consistent with two-scale-factor universality predictions.