exp3.phychem transference number - CHM171L Physical...

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CHM171L Physical Chemistry 2 Laboratory 1stQuarter SY 2010-2011 CONDUCTIMETRY: Determination of the Electrical Properties of Solutions Engr. Edna Calderon 1 ; MELLENDREZ, Kristine Jhalene; Ngan, Emil Joseph; Obien, Joanna Marie 2 1 Professor, School of Chemical Engineering, Chemistry and Biotechnology, Mapua Institute of Technology; 2 Students, CHM171L/A11, School of Chemical Engineering, Chemistry and Biotechnology, Mapua Institute of Technology ABSTRACT In this experiment, conductimetry was being tackled. Determination of the electrical properties of solutions was the main concern. Electrical conductivity or specific conductance is a measure of a material's ability to conduct an electric current . When an electrical potential difference is placed across a conductor, its movable charges flow. Consequently, there would be a rise to an electric current. The conductivity σ is defined as the ratio of the current density J to the electric field strength E. The objectives of the experiment were mainly to determine the relative mobility of some monovalent ions by measuring the conductance of solutions of the electrolyte and to determine the dissociation constant of a weak electrolyte. In order for the objectives to be accomplish or to be done is that one should have the proper equipment. In this case the only equipment that is to be use is the conductivity meter in which in this apparatus has an electrode that is to determine the conductivity level of the solution. Keywords : conductimetry, electrical conductivity, specific conductance, conductivity meter INTRODUCTION 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. The conductivity of a solution depends on: • The quantity of ions. The more ions a solution contains, the higher will be its conductivity. • The kind of ions. The smaller and more mobile an ion, the better will be its + - + - electrical conductivity. • The solvent. The more polar the solvent, the better the ionization of the solutes it contains. In relation to this, water is an ideal solvent, while methyl alcohol is also good. • The temperature. Ionic mobility increases with rising temperature. According to the type of ion, the conductivity increases by 1-3% / ºC. Pure water does not conduct electricity, but any solvated ionic species would contribute to conduction of electricity. An ionically conducting solution is called an electrolyte solution and the compound, which produces the ions as it dissolves, is called an electrolyte. A strong electrolyte is a compound that will
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exp3.phychem transference number - CHM171L Physical...

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