question archive Determining the Kspof Calcium HydroxideCalcium hydroxide is an ionic solid that is sparingly soluble in water
Determining the Kspof Calcium HydroxideCalcium hydroxide is an ionic solid that is sparingly soluble in water
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Determining the Kspof Calcium HydroxideCalcium hydroxide is an ionic solid that is sparingly soluble in water. A saturated, aqueous, solution of Ca(OH)2 is represented in equation form as shown below.Ca(OH)2 (s) ↔ Ca2+ (aq) + 2OH- (aq)The solubility product expression describes, in mathematical terms, the equilibrium that is established between the solid substance and its dissolved ions in an aqueous system. The equilibrium expression for calcium hydroxide is shown below.Ksp = [Ca2+][OH-]2The constant that illustrates a substance's solubility in water is called the Ksp. All compounds, even the highly soluble sodium chloride, have a Ksp. However, the Ksp of a compound is commonly considered only in cases where the compound is very slightly soluble and the amount of dissolved ions is not simple to measure. Your primary objective in this experiment is to test a saturated solution of calcium hydroxide and use your observations and measurements to calculate the Ksp of the compound. You will do this by titrating the prepared Ca(OH)2 solution with a standard hydrochloric acid solution. By determining the molar concentration of dissolved hydroxide ions in the saturated Ca(OH)2solution, you will have the necessary information to calculate the Ksp.
OBJECTIVES: In this experiment, you will? Titrate a saturated Ca(OH)2 solution with a standard HCl solution.? Determine the [OH-] for the saturated Ca(OH)2 solution.? Calculate the Ksp of Ca(OH)2.
I'm not sure if I'm doing this correctly, nor do I understand how to get the percent difference in question 4. I think I got the first 3 questions correct. The equivalence point for Trail 1 is 5.2321 mL and Trial 2 is 5.027 mL.
1. Calculate the [OH-] from the results of your titrations. Explain your calculations.
2. Calculate the [Ca2+]. Explain your calculations.
3. Calculate the Ksp for calcium hydroxide. Explain your calculations.
4. Find the accepted value of the Ksp for calcium hydroxide and compare it with your value. Calculate the expected [OH-] based on the accepted Ksp and compare this to your experimental [OH-] by percent difference. Discuss the discrepancy and suggest possible sources of experimental error.
