Conductimetric Properties of Benzoic Acid in Water and 1-Propanol Mixtures at the Temperatures from 298.15 to 313.15K

Abstract

Molar conductance of benzoic acid in 1-propanol-water mixtures has been measured in the composition of 0, 5, 10, 15, 20, 30 and 40 wt % of 1-propanol at 5 K interval from 298.15 to 313.15 K. The limiting molar conductance Λ o and the thermodynamic dissociation constant constant pKa were estimated from the measured conductance data using Bray-Kraus and Fuoss-Kraus equations. An approximate linear dependence of pK a with the reciprocal of the dielectric constant of the media was observed and this trend may be due to the dominating effect of the coulombic forces of attractions between the opposite ions over the other types of attractions. The gradual decreases of Λ o with the increase of 1-propanol fraction in the binary mixtures of 1-propanol and water may be attributed to relative increase in the viscosities of 1-propanol-water mixtures. The Walden product and normalized Walden product (nwp) of the benzoic acid in the seven binary mixtures have been calculated and a qualitative proposal has been made regarding their variation with wt% of 1-propanol. The free energies of transfer ΔG°t r, also have been computed for the acid in the solvent mixtures. The change of pK a with the solvent composition has been discussed in terms of the free energy of transfer from water to the 1-propanol-water mixtures.

Volumetric and Ultrasonic Velocity Studies of Urea and Thiourea in Aqueous Solution

“…Hepler [17][18] argued that a positive value of (∂ 2 ϕ v 0 /∂T 2 ) p is associated with structure making nature, whereas a negative value of (∂ 2 ϕ v 0 /∂T 2 p is associated with a structure braking nature. It is apparent that the values of (∂ 2 ϕ v 0 /∂T 2 ) p are negative for urea and thiourea in aqueous solution are negative and (∂ 2 ϕ v 0 /∂T 2 ) p value for thiourea is more negative than urea solution.…”

Dissociation Constant Studies of 2-Substituted 4-Formylbenzoic Acid based on Conductometric Parameters using Fuoss-Hsia Theories

“…The stability of substitution in 4-position of benzoic acid, and stability of the mentioned compound at different solvent was estimated [13,14]. The conductometric study of benzoic acid has been studied with the use of many equations for finding dissociation constant, thermodynamic parameters and equivalent conductance at infinity dilution [15,16]. The other studies show that the temperature, type of electrolytes, solvents and conductometric equations play an important role in shaping conductometric curve at different solvents [17,18].…”