Question

Pre-Laboratory Assignment Create a table to record the data for this lab exercise. Leave space for each piece of data you need to record during the lab (measurements, observations, etc.), as well as information you will look up and /or calculate. 1. Why do you need to prepare saturated solutions of Ca(OH)2 in the absence and presence of CaCl2 a week before testing them? a. It takes time for the dissolution of Ca(OH)2 to reach equilibrium. b. The mixtures have to settle until clear supernatants are formed. c. The titration needs to be done on the clear supernatant but not the supernatant with fine particles of Ca(OH)2. d. All above 2. Which of the following descriptions about solubility is NOT correct? a. Solubility is measured in terms of the maximum amount of solute dissolved in a solvent at equilibrium b. Solubility of an ionic compound decreases in the presence of common ions, e.g., Ca2 and OH-for Ca(OH)2 C. The concept of solubility is limited to ionic compounds, and does not include organic compounds. d. The solubility can be expressed in various units including molarity! 3. A saturated solution of Ca(OH)2 was prepared in pure deionized water and the supernatant was titrated with 0.0250 M HCl. 10.00 mL of HCl standard solution was used to neutralize 15.00 mL of Ca(OH)2 supernatant. Please answer the following questions: 3-1. Which of the chemical reactions expresses the dissolution of Ca(OH)2? a. Ca(OH)2 (s) 5 Ca²+ (aq) + 2 OH(aq) b. Ca? (aq) + 2 OH(aq) = Ca(OH)2 (S) c. Ca(OH)2 (s) + 2 HCI (1) = CaCl2 (aq) + 2 H20 (1) d. CaCl2 (aq) + 2 H2O(l) 5 Ca(OH)2 (5) + 2 HCl (1)