Chem. 122 Lab
31 March 2014
The purpose of this lab was to determine the solubility product of a sparingly soluble salt, by titration method. Introduction
Solubility product constants are used to describe saturated solutions of ionic compounds of relatively low solubility. A saturated solution is in a state of dynamic equilibrium between the dissolved, dissociated, ionic compound and the undissolved solid. Since the equilibrium constant refers to the product of the concentration of the ions that are present in a saturated solution of an ionic compound, it is given the name solubility product constant, and given the symbol Ksp. Solubility product constants can be calculated, and used in a variety of applications. Experimental Procedures
The weight of approximately 1-2 g of solid Ca was taken and transferred to a 250-mL Erlenmeyer flask with 100 mL of distilled water. The flask sat for 15 minutes, allowing the suspension to settle. A filtration apparatus was set up to collect enough saturated solution of calcium hydroxide for titration. A burette with 0.1 M HCL was set up. A plastic pipette was used to draw about 75 mL of clear solution from the top of the saturated Ca solution and transferred to a funnel for filtration. 25 mL of the filtrate was added to a 250-mL Erlenmeyer flask with 25 mL of distilled water, 2-3 drops of Bromocresol purple, and titrate with 0.1 M HCl. The endpoint was marked by a pale yellow color. The initial and final burette readings were recorded and the experiment was repeated with another 25 mL of the filtrate. Data
Molarity of HCl (Ma)
Volume of saturated Ca(OH)2 soltuion (Vb)
Initial burette reading
Final burette reading
Volume of HCl (Va)
OH- ion concentration (Mb)
Average OH- ion concentration
References: Experiments in General Chemistry. Claflin: Department of Chemistry, 2013. Print.
"Solubility Products." Solubility_Products. N.p., n.d. Web. 31 Mar. 2014.
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