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Determining the Ksp of Calcium Hydroxide by Titration of Saturated Ca(Oh)2(Aq) with Hcl(Aq)

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Determining the Ksp of Calcium Hydroxide by Titration of Saturated Ca(Oh)2(Aq) with Hcl(Aq)
Determining the Ksp of Calcium Hydroxide by Titration of Saturated Ca(OH)2(aq) with HCl(aq)

Abstract: Titration is a technique that has been used in this experiment to identify the Ksp value of calcium hydroxide in order to determine the extent to which the compound is soluble in water. A known volume of 50 mL of hydrochloric acid, a concentration of 0.05 M hydrochloric acid, a volume of 50 mL calcium hydroxide base, an unknown concentration of base and an acid-base indicator (bromothymol blue) has been used in this experiment to determine the concentration of calcium hydroxide. From the results tabulated, a Ksp value of 1.26 x 10-7 has been retrieved indicating that calcium hydroxide has a low solubility in water. On the other hand, a value of 98.4 % error has been tabulated which indicates that there are both human and experimental errors which may have impacted the overall results.

Introduction: Ksp is defined as the ratio of concentrations of dissolved ions and undissolved ions of a precipitate at equilibrium. This can also be expressed using the rate law equation. For example , the solubility product of calcium hydroxide can be written as, Ksp = [Ca2+] [OH-]2 (1) This chemical system is in a dynamic equilibrium between solute and solvent particles in a saturated solution in a closed system. Therefore, the system is in solubility equilibrium. The solid, Ca(OH)2 dissolves in solution and the ions crystallize, therefore, the forward rate (dissolution) equals the reverse rate (crystallization). Since both dissolving and crystallizing processes take place at the same rate, no observable changes would occur in either the concentration of the ions in solution or in the quantity of solid present, Ca(OH)2. The mixture contains both



References: Introducing Chemical Equilibrium. Retrieved on November 14, 2010 from the World Wide Web: http://www.avogadro.co.uk/chemeqm /chemeqm.htm Experiment 10: Solubility Product for Calcium Hydroxide. Retrieved on November 14, 2010 from the World Wide Web: http://www.pdfdownload.org/pdf2html/pdf2html_vuzit.php?url=http%3A%2F%2Fwww%2Echemistry%2Eucsc%2Eedu%2Fteaching%2Froland%2FChem1N%2Fprocedures%2F1N%5F10%5FKspproc%2Epdf&images=no

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