Exp043

Dominican University Student Project 1/23/09 Raquel Robles

Benzoic Acid || SMILES || OC(=O)C1=CC=CC=C1 || Type/Classification || Carboxylic Acid || Chemspider Link || http://www.chemspider.com/Search.aspx?q=benzoic+acid || Methanol || SMILES || OC || Average Solubility (g/100g) || 37.8/100 || Average Concentration (mol/L) || 2.37 || Chemspider link of solvent || http://www.chemspider.com/Search.aspx?q=methanol ||
 * Solute** ||
 * Solute** ||
 * Solvent** ||
 * Solvent** ||

Solubility Procedure This lab started by gathering the solute (Benzoic acid) and the solvent (Methanol). The solute was placed inside a beaker and 5 mL of the solvent was pipetted into a 25 mL glass Pyrex Erlenmeyer flask for each trial. The solute was transferred to the mixing flask in small increments using a spatula. It was immediately noticeable that the solute was extremely soluble in the solvent. To quicker the mixing process, a sonic wave bath was used to dissolve large amounts of solute. Saturation was reached when a couple of small white flakes of solute were not dissolving. Four samples were created. The solution was transferred to a small test tube using a glass pipette; then were placed inside a centrifuge to remove any extra solute in solution. The tubes were in the centrifuge for 5 minutes each. The evaporation vessels (20 mL scintillation vials) were weighed at this time. When the test tubes were taken out the centrifuge, a 5 mL glass pipette was used to measure the volume of each solution, and then the solution was transferred to the evaporation vessels. The evaporation vessels with the solution inside them were weighed. A hot water bath was set up using a 125 mL glass Pyrex beaker 1/5 filled with water on top of a “Lab Companion” hot plate. The vessels were placed inside a hot water bath and while trying to transfer them carefully, one fell over inside the bath. The liquid and vessel were removed and another solution was created in the same way as the others as a replacement. Then, this vessel was also placed inside the hot water bath. A thermometer was placed in the beaker with water to make sure the water did not get unnecessarily hot. The methanol evaporated quickly at around 80 degrees Celsius and left behind solute. The evaporation vessels with the solute in them were weighed and left out to dry more thoroughly. After prolonged drying, the samples were weighed again for a more accurate reading.


 * TABLE 1: Raw Data and Calculated Solubility**

EXPERIMENT || 1 || 2 ||  3 ||  4 || Solute |||||||| Benzoic Acid || Solvent |||||||| Methanol || Solvent Density (g/mL) |||||||| 0.792 || Mass of Empty Evaporation Vessel (g) || 12.812 || 12.854 || 12.790 || 12.872 || Volume of Solution (mL) || 6.0 || 6.4 || 6.0 || 6.0 || Mass of evaporation vessel + solution (g) || 17.572 || 17.669 || 17.448 || 17.322 || Mass of evaporation vessel + solute (g) || 14.675 || 14.716 || 14.591 || 14.579 || Mass of evaporation vessel + solute after prolonged drying (g) (used for calculations) || 14.674 || 14.722 || 14.416 || 14.573 || Solubility (g/mL) || 0.310 || 0.292 || 0.271 || 0.284 || Concentration (mol/L) || 2.54 || 2.39 || 2.22 || 2.32 || Molality (mol/kg solution) || 5.24 || 5.19 || 4.39 || 5.07 || Solubility (g/100g solution) || 39.1/100 || 38.8/100 || 38.7/100 || 38.4/100 ||