= 143.19 x – 0.165
CHM171L / A11 Physical Chemistry Laboratory 2
Quarter S.Y. 2010-2011
Conductimetry: Determination of the Electrical Properties of Solutions
, Co, Argenia B.
Professor, CHM171L/A31, School of Chemical Engineering, Chemistry and Biotechnology, Mapua Institute of Technology;
CHM171L /A31 , School of Chemical Engineering, Chemistry and Biotechnology, Mapua Institute of Technology
The experiment mainly focused on Conductimetry, particularly in determination of electrical properties of certain solutions. The experiment aims
to determine relative mobility of some monovalent ions through measuring the conductance of solutions of electrolytes, also to acquire
dissociation constant of a weak electrolyte. The experiment was actually divide into two parts, and from part A (Electrolytic Conductance and
Ionic Mobility) based from the values
obtained, it is found that HCL has the highest conductance, followed by NaOH, NaCl, NH
has the lowest conductance. For part B (Determination of dissociation constant of a weak electrolyte), the experiment
concentration of KOH and water, from that
of concentration vs conductance enable the computation for dissociation constant of NH
at 1 M and O.01 M. also, from the graph it shows the conductance changes proportionally with the concentration. KOH was used since its
concentration is equal to the concentration of Ammonia ionized in the solution.
Conductimetry is concerned with the electrical conductivity of electrolytes. Measurements are made indirectly across the resistance of the
solution with alternating current, since direct current would alter the composition of the sample solution by electrolysis. Conduction or electrical
conduction is the mechanism by which charge flows or the movement of electrically charged particles through a transmission substance
(electrical conductor). This movement of charge constitutes an electric current and the physical parameters governing this transport depend upon
the substance. Therefore, conductivity (electrical conductivity or specific conductivity) is a measure of the ability of a substance to conduct an
electric current. In solutions, current is carried by free moving ions (positive and negative). A conductive solution is known as an 'electrolyte' and
includes solutions of ionic salts or of compounds that ionize in solution (e.g. acids and bases). Conductivity is the reciprocal (inverse) of
electrical resistivity and has the SI units of siemens per metre (S•m
). Electrical conductivity is commonly represented by the Greek letter .
Experience has shown that for reasons related to the measuring technique (polarization phenomena) better results are obtained when the
measuring frequency is adapted to the range of measurement.
The conductivity of a solution depends on: