EXPERIMENT 2

# EXPERIMENT 2 - CHM170L/B41/GroupNo.6 Experiment No 2...

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MAPUA INSTITUTE OF TECHNOLOGY School of Chemical Engineering and Chemistry CHM170L / B41 / Group No. 6 Experiment No. 2 MEASUREMENT OF DENSITY AND DETERMINATION OF PARTIAL MOLAR VOLUME OF ETHANOL-WATER SYSTEM TAN, Aieocellis F. TANGARA, Neil Patrick P. VELASCO, Christel Charmaine D. VILLAFLOR, Arthur C. ABSTRACT This experiment intends to measure the density of a liquid, having different concentrations (10% by volume increments) of ethanol-water solutions with the use a pycnometer. Molecules that are mixed with different molecules would interact differently, that is why in this experiment, partial volumes are also considered due to ethanol and water mixture. The pycnometer was calibrated using a known standard (water) and prepared different solutions having 10% of increment of concentrations. Densities have been calculated using the mass of each sample and the known volume of the pycnometer. As the volume of water increased (volume of ethanol decreased), the density of the ethanol-water system has been observed to increase. The reason for such phenomena shall be explained further in the succeeding parts of this experiment.

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MAPUA INSTITUTE OF TECHNOLOGY School of Chemical Engineering and Chemistry CHM170L / B41 / Group No. 6 Introduction Density The density of a material is defined as its mass per unit volume . The symbol of density is ρ (the Greek letter rho ). Mathematically: Density = Mass Divided By Volume where: ρ (rho) is the density, m is the mass, V is the volume. Different materials usually have different densities, so density is an important concept regarding buoyancy , metal purity and packaging . In some cases density is expressed as the dimensionless quantities specific gravity (SG) or relative density (RD), in which case it is expressed in multiples of the density of some other standard material, usually water or air/gas. Pycnometer A pycnometer (from Greek : πυκνός (puknos) meaning "dense"), also called pyknometer or specific gravity bottle, is a device used to determine the density of a liquid. A pycnometer is usually made of glass, with a close-fitting ground glass stopper with a capillary tube through it, so that air bubbles may escape from the apparatus. This device enables a liquid's density to be measured accurately by reference to an appropriate working fluid, such as water or mercury , using an analytical balance . If the flask is weighed empty, full of water, and full of a liquid whose specific gravity is desired, the specific gravity of the liquid can easily be calculated. Partial Molar Property A partial molar property is a thermodynamic quantity which indicates how an extensive property of a solution or mixture varies with changes in the molar composition of the mixture at constant temperature and pressure , or for constant values of the natural variables of the extensive property considered. Essentially it is the partial
MAPUA INSTITUTE OF TECHNOLOGY School of Chemical Engineering and Chemistry

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EXPERIMENT 2 - CHM170L/B41/GroupNo.6 Experiment No 2...

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