TELEEDUCATION: VOLUMETRIC CHEMICAL ANALYSIS
Last Update 14/8/1998
TITRATION: Volumetric analytical quantitative chemical practice. The objective of the titration is the determination of the concentration or the formula weight mass from the titrated chemical material composing a pure liquid or a solution. The titrant chemical material, composing another liquid or solution is used to meet the objective above, by means of a chemical reaction that will present at least one observable change. Generally the buret is filled with the titrant, while the titrate is in the conical flask. Next, the titrant is added by carefully opening the stopcock on the buret. The chemical reaction of the titrate with the titratant enables the titration. On every titrant addition, the reaction consumes part of the titrate. If all the titrate is consumed by the last titrant addition, the equivalence point is reached. It is very easy to reach the equivalence point with the simulator, but not so easy in the experiment with the chemical reagents. Experimentally approximations are acceptable, they depend on the precision of the analytical balance used to prepare the solutions, on the precision of the volumetric vessels and on the stability of the temperature on the surroundings. Best result quality is achieved when the chemical energies of attraction between the titrate component and titrant forming the reaction product are high and when the chemical energies of attraction between titrate and solvent and titrant and solvent will not compete to revert the product into the reagents. Additionaly impurities in the materials and in the environment, particulates in suspension in the air, liquid evaporation, the chemical stability of the components, reaction speed and the operator’s technical performance play a role on the result quality. Opening the simulator stopcock with the cursor by a push and drag mouse action counter clokwise, ten different microlitres values of NaOH 0.1 mole L-1 are liberated over 50 mL HCl on each vertical mouse pulse displacement. Horizontal displacements liberate equal microliters quantities of NaOH. To restart the experiment click on the repeat button (after washing electronically the vessels). New Java applet.
Please, send your comments to Prof. Dr. Roberto Andrea Müller
Universidade Federal de Viçosa - Viçosa - Minas Gerais - Brazil - 36571-000