Viscosity behavior of benzoic acid and benzoate ion in aqueous solution

Relative viscosities of aqueous solutions of benzoic acid and benzoates of lithium, sodium, potassium, and ammonium are measured. In the temperature range 25–35°C, the Jones-Dole viscosityB coefficients of the benzoate ion decrease with increasing temperature, indicating a net structure-making effect. The somewhat larger value of theB coefficient for the benzoate ion than that for the benzoic acid molecule confirms similar behavior for the acetate ion and acetic acid in aqueous solutions although the effect is much smaller.