Solubility

Edit Experiment

VIDEO LINKS:

Lab Experiments (Write protocols and perform experiments based on these):

Part 1
  1. Making a Saturated Ca(OH)2 Solution
  2. pH of Saturated Ca(OH)2 Solution
Part 2
  1. Making 0.05 M KHP Solution
  2. Titration of Saturated Ca(OH)2 Solution
Part 3
  1. Common Ion Effect
  2. pH of Ca(OH)2 and CaCl2 Mixture
  3. Titration of pH of Ca(OH)2 and CaCl2 Mixture
Part 4
  1. Temperature Dependence of Calcium Hydroxide Solubility

Technique videos

  1. Calibrating a pH probe
  2. Charging the burette

The prelab must include Experimental Protocol, Chemical Table and Equipment Table.

The lab report requires all sections (including prelab sections) to be completed in one document.

Experimental Protocol

(Analysis) Watch the experiment videos.  Take notes on the protocol.  Stop the video and re-watch as necessary to acquire the details of the procedure.  Write out the protocol for each part of the experiment.  (It can be written in sequential steps.  Complete sentences are not necessary.)  This is the protocol you will follow, so be detailed.

Data Collection

(Acquiring competencies) Following your detailed protocol based on the videos, perform all the experiments. Record your observations and take pictures of your key steps in the process.  Your observations and images need to be incorporated in your data section and this section should be as detailed as possible as you will use this information to complete your discussion.

Data Processing

  1. (Representation) Write the equation for the dissolution of calcium hydroxide in water.
  2. (Interpretation) Using your balanced chemical equation that describes the dissolution, interpret its meaning on the microscopic and macroscopic scale.
  3. (Representation) Write the Ksp expression for calcium hydroxide.
  4. (Representation) Write the balanced molecular equation for the reaction of calcium hydroxide and KHP.
  5. (Existing knowledge, research, and views) Indicate the value for the Ksp of calcium hydroxide and include your reference.
  6. (Manipulation) Using the pH value of your saturated calcium hydroxide solution, calculate the hydroxide ion concentration.
  7. (Manipulation) Using the pH value of your saturated calcium hydroxide solution, calculate the calcium ion concentration.
  8. (Manipulation) Using the pH value of your saturated calcium hydroxide solution, calculate the Ksp.
  9. (Manipulation) Using your data from the titration of the saturated calcium hydroxide solution, calculate the hydroxide ion concentration.
  10. (Manipulation) Using your data from the titration of the saturated calcium hydroxide solution, calculate the calcium ion concentration.
  11. (Manipulation) Using your data from the titration of the saturated calcium hydroxide solution, calculate the Ksp.
  12. (Manipulation) Calculate the mass of dissolved calcium hydroxide from your filtration experiment and use it to derive the Ksp.
  13. (Manipulation) Knowing the concentrations of calcium ion from the calcium chloride added to the calcium hydroxide solution, and the literature value for the Ksp, calculate the expected pH of the resulting solution.
  14. (Manipulation) Using the pH value of your saturated calcium hydroxide solution with calcium chloride, calculate the hydroxide ion concentration.
  15. (Manipulation) Using the pH value of your saturated calcium hydroxide solution with calcium chloride and the amount of calcium chloride added, calculate the calcium ion concentration.
  16. (Manipulation) Using the pH value of your saturated calcium hydroxide solution with calcium chloride and the amount of calcium chloride added, calculate the Ksp.
  17. (Manipulation) Using your data from the titration of the saturated calcium hydroxide solution with calcium chloride, calculate the hydroxide ion concentration.
  18. (Manipulation) Using your data from the titration of the saturated calcium hydroxide solution, with calcium chloride calculate the calcium ion concentration.
  19. (Manipulation) Using your data from the titration of the saturated calcium hydroxide solution, with calcium chloride calculate the Ksp.
  20. (Existing knowledge, research, and views) Identify the value of the free energy, enthalpy, and entropy for the dissolution of calcium hydroxide at room temperature and include your reference.
  21. (Manipulation) Calculate the ΔGo based on the Ksp at room temperature.
  22. (Manipulation) Calculate the ΔHo based on the Ksp values at different temperatures.
  23. (Manipulation) Calculate the ΔSo based on your previous values.
  24. (Analysis) Calculate the % error between the literature and the experimental free energy.
  25. (Analysis). Calculate the % error between the literature and the experimental enthalpy.
  26. (Analysis) Calculate the % error between the literature and the experimental entropy.
  27. (Assumptions and Analysis) Fill in the following table using the observations and data from your experiments.
Assumptions made Testing the assumption If assumptions are wrong ...
The distilled water is pure Evaporate it and check for residue The density would change depending on the density of the equilibrium would shift depending on the contaminants

Discussion

Write a minimum one-page (12 font, single spaced) discussion on the experiment conducted this week. Address at least one question in each category as fully as possible integrating the collected data, providing explanations for the observed trends, and evaluating whether your original assumptions about the experiment were validated by the results. The assignment will be graded on completeness, clarity of the explanations and the meaningful integration of the collected and calculated data. Correct grammar and appropriate format for the chemical formulae and chemical reactions is expected. You may use the outline included at the end of this document on how to build your essay to address each category.
  1. (Existing knowledge, research, and views) Classify calcium hydroxide as strong or weak, acid or base.
  2. (Existing knowledge, research, and views) Define common ion effect.
  3. (Analysis) Using your observations and calculations comment on your success in observing the common ion effect in your pH measurements.
  4. (Analysis) Using your observations and calculations comment on your success in observing the common ion effect in your titration experiments.
  5. (Analysis) Compare the results of your pH experiments and your titrations and make a supported argument for which technique is more effective at demonstrating the common ion effect.
  6. (Analysis) Explain the correlation between pH and dissolution of calcium hydroxide using dissolution equation.
  7. (Analysis) Using your observations at different temperatures, identify the correlation between pH and temperature in the dissolution of calcium hydroxide.
  8. (Analysis) Provide a supported argument for the differences between the Ksp values determined by titration, using the pH-probe and the filtration method for the saturated calcium hydroxide solution.
  9. (Analysis) Provide a supported argument for the differences between the Ksp values determined by titration and using the pH-probe method for the saturated calcium hydroxide solution with added calcium chloride.
  10. (Experiment design) Describe a protocol to calculate the Ksp of a neutral salt.
  11. (Assumptions and limitations) Using your observations and ΔHo calculations as supporting arguments, classify the dissolution of calcium hydroxide as exothermic or endothermic. Comment on the agreement between your observations and calculations.
  12. (Assumptions and limitations) Using your observations and ΔGo calculations as supporting arguments, classify the dissolution of calcium hydroxide as spontaneous or nonspontaneous. Comment on the agreement between your observations and calculations.
  13. (Analysis) Using your calculated % error values for ΔHo. ΔGo, ΔSo, comment on the accuracy of your measurements and identify at least 2 sources of error.
  14. (Analysis) Provide a supported argument for using phenolphthalein for monitoring the titrations. (HINT: classify KHP as a strong or weak acid)