The effect of solute concentration on fluidity and structure in aqueous solutions of electrolytes—IV. Sulphates and carbonates

Abstract

Studies on the effect of concentration on the temperature dependence of fluidity in solutions of sulphates and carbonates show that hydration of the anion contributes to the inhibition of fluid motion in these systems. Where the hydration structure of the anion is such that hydrogen bonding can occur with cationic hydration shells there is gross inhibition of flow; even where anionic hydration does not form such bonds and both ion species exist as discrete hydrated entities, fluidity is strongly suppressed. Where the solution contains positively hydrated anions and negatively hydrated cations its fluid characteristics are generally similar to one that contains positively hydrated cations and negatively hydrated anions. In solutions of MgSO 4, CuSO 4 and Li 2SO 4 up to about 0·05 m and to a lesser extent Na 2SO 4, intrinsic water structure is enhanced, but above this concentration water structure is destroyed and the total water of the system is influenced by the forces responsible for hydration.