Chemistry > QUESTIONS & ANSWERS > Houston County High SchoolHON. CHEMISTRY 1013.2.7 Practice - Solubility Equilibrium (All)

Houston County High SchoolHON. CHEMISTRY 1013.2.7 Practice - Solubility Equilibrium

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3.2.7 Practice: Solubility Equilibrium AP Chemistry Sem 2 Points Possible:25 Name: Kayla James You will need to use a calculator and a periodic table to complete this activity. 1. Predict the solubility of each of the following compounds at 25°C. Then determine which of the two compounds in each case is more soluble. Afterward, decide whether you could have determined which of the two compounds was more soluble just by comparing the Ksp values. Explain why or why not. All K 2. Interpret the solubility data given for each of the following compounds at 25°C. Then determine which of the two compounds in each case has a higher Ksp value at 25°C. Afterward, decide whether you could have determined which of the two compounds has a lower Ksp just by comparing the solubilities. Explain why or why not. b. Bismuth iodide, BiI3, a compound used in medical imaging to explore the tiny spaces between nerves, has a solubility of 1.30 × 10–5 M. Zinc selenide, ZnSe, a compound used to produce blue light-emitting diodes, has a solubility of 1.9 × 10–13 M. (3 points) 3. Answer the following questions by interpreting the data that are given regarding the relative solubilities of the compounds. In each case, show your calculations. a. A solution contains 2.0 × 10–3 M Ba2+ and 1.0 × 10–2 M Sc3+. A source of F– is slowly added to the solution. Will BaF2 (Ksp = 1.84 × 10–7) or ScF3 (Ksp = 5.81 × 10–24) precipitate first? (4 points) BaF2 [F-]2  Ba2+¿ Ksp ¿  1.84× 10-7 2.0× 10-3  0.92 x 10-4 [F-]  √0.92×10-4 = 0.95 x 10-2 M ScF3 [F-]3  Ksp Sc+3  5.81 1.0××10 10--224  5.81 x 10-22  0.581 x 10-21 [F-]  (0.581 x 10-21)1/3 = 0.83 x 10-7 ScF3 will precipitate first. b. Determine the solubility at 25°C of Cd(IO3)2 in water and in 0.20 M CdCl2. Ksp of Cd(IO3)2 is 2.5 × 10–8 at 25°C. (4 points) Cd(IO3)2  Cd2+ + 2IO3- Ksp = 4s3 2.5× 10-8 4 = 4 s3 4 s3 = 6.25 x 10-9 S = (6.25 x 10-9)1/3 = 1.84 x 10-3 M 4. Analyze the figure shown of a salt (sodium chloride) dissociating in a solvent (water). a. Identify two factors that affect the change in entropy that occurs during the formation of the solution. State whether each factor causes an increase or a decrease in entropy. (1 point) b. Is the entropy of the solution usually greater than or less than that of the solid salt? (2 points) c. State whether the change in enthalpy is positive or negative for each of the following steps in the formation of a solution: Solute dissociates into ions. Solvent molecules overcome forces binding them together. Solvent molecules surround the solute ions. (1 point)

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