Lithium perchlorate (LiClO4) is widely used as an
electrolytic salt. Lithium perchlorate and other Li-salts have been used in the
optimization of electrolyte solutions in organic aprotic solvents for primary
and secondary rechargeable lithium batteries. Conductance of Li-Picrate was
measured in different temperatures (25 oC, 35 oC, and 45 oC). The limiting
equivalent conductance (𝜆0) and the ion association
constant (KA) for Li-Picrate in propylene carbonate (PC) and tetrahydrofuran
(THF) mixture (PC+THF) solvents at different percentages were evaluated using
Debye-Huckel Onsager equation. It is observed that the limiting equivalent
conductance increased linearly with the increase in temperature and the
association constant values decreased with the rise in temperature.
Thermodynamic parameters [i.e., Standard Gibbs Free Energy Change (iG0),
Standard Enthalpy Change (iH0), and Standard Entropy Change (iS0) are estimated
from the temperature dependence of the ion-association constant. The positive
values of iS0 and positive values of iH0 indicate the ion-association process
occurred spontaneously as well as endothermic at all respective temperatures.
Supported by absorbance data from this primary study, it may be concluded that
room temperature solubility of Li-Picrate in mixed (PC+THF) solvents at
different percentages is higher than at higher temperatures. The entropy of
ionization decreases slowly with an increase in temperature. From this angle,
the ionization should decrease with temperature. Conductivity data helps us to
conclude that if we go from room temperature to higher temperature conductance
increases for Li-Picrate in (PC+THF) solvents at different percentages. This is
due to the switchover of ion-pair to ionic dissociation of Li-Picrate salt.
Author(s) Details
Ashoke Hazra
Department of Chemistry, A.K.P.C. Mahavidyalaya,
Subhasnagar, Bengai, Hooghly, India.
Please see the book here:- https://doi.org/10.9734/bpi/cmsdi/v9/3880
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