SAFETY NOTES: Sodium hydroxide is caustic and can cause skin irritation and burns. Use all due precautions when handling.

GENERAL INSTRUCTIONS: Students will work as a class and share data for this experiment so that all eight titrations can be completed in the time allotted, i.e., each student should complete two of five different temperature titrations and report their findings to the rest of the class.

Part 1: Titration of a room temperature, saturated Ca(OH)2solution
	Obtain a buret and rinse it well with DI water.
	Use a clamp to attach the buret to the ring stand on your bench, and then set a magnetic stirrer (hotplate) underneath it.
	Pour approximately 30 mL of  0.05 M HCl solution into a clean, dry 50 or 100 mL beaker. Record the concentration of the acid.
	Rinse the inside of the buret with a few milliliters of the HCl solution, making sure all the walls of the buret are coated. Collect the rinse solution in a beaker labeled “Waste”.
	With the stopcock closed, pour the remainder of the HCl solution into the buret. Place a small waste beaker under the buret and slowly open the stopcock until the solution begins to drip out.
	Then close the stopcock and make sure there are no air bubbles in the tip of the buret. Also make sure that the level of liquid in the buret is at or below the 0.00 mL line. Dispose of the wash solution in your waste beaker.
	Add about 100 mL of distilled water to a 250mL Beaker and using a thermometer record its temperature to 0.1°C. Add 2.0 g of solid Ca(OH)2 with constant stirring until the salt no longer dissolves.
	Using a funnel, strain this solution through qualitative filter paper into a clean, dry 125 mL Erlen-meyer filter flask. Note: Only filter small amounts of solution at a time to avoid "swamping" the filter paper.  The filtrate solution should be clear when filtration is complete.  A "cloudy" filtrate indicates the presence of particulates that will throw off the titration results.  Re-filter any "cloudy" filtrates until they are clear.
	Pipet 10.00 mL of this clear solution into another clean, dry 100 mL Beaker. Add approximately 25 mL of distilled water and 10-12 drops of the bromothymol blue indicator. Gently slide a magnetic stir bar into the flask.
	Set the flask on the stirrer and begin stirring at a gentle rate. (Make sure there is no splashing of the solution.) Record to two decimal places the beginning volume level of HCl in the buret.
	Begin the titration, allowing the titrant to fall from the buret at a rapid drop-by-drop pace. During this addition, the initial blue color will begin to turn green and then yellow. The end point is reached when the entire solution turns yellow. (Run your mouse over the picture to see the final color) Your goal is to deliver the exact volume needed to reach the endpoint. When you have reached the end point, record the final volume in the buret (again to two decimal places) and calculate the volume of titrant delivered.
	Pour the titrated solution into the waste container, but don’t lose your stir bar.
Part 2: Titration of a elevated temperature, saturated Ca(OH)2solution
	Add about 100 mL of distilled water to a 250 mL beaker. Place it on a hotplate and bring the water to between 50oC and 70oC. After the water has been at temperature for several minutes, add about 2 g of solid Ca(OH)2 to the water with constant stirring until the salt no longer dissolves. Take a final temperature reading at saturation.
	Using a funnel, quickly strain this solution through qualitative filter paper into a clean, dry 125 mL Erlen-meyer filter flask. Note: Only filter small amounts of solution at a time to avoid "swamping" the filter paper.  The filtrate solution should be clear when filtration is complete.  A "cloudy" filtrate indicates the presence of particulates that will throw off the titration results.  Re-filter any "cloudy" filtrates until they are clear.
	Pipet 10.00 mL of this clear solution into another clean, dry 100 mL Beaker. Add approximately 25 mL of distilled water and 10-12 drops of the bromothymol blue indicator. Gently slide a magnetic stir bar into the flask.
	Set the flask on the stirrer and begin stirring at a gentle rate. (Make sure there is no splashing of the solution.) Record to two decimal places the beginning volume level of HCl in the buret.
	Begin the titration, allowing the titrant to fall from the buret at a rapid drop-by-drop pace. During this addition, the initial blue color will begin to turn green and then yellow. The end point is reached when the entire solution turns yellow. (Run your mouse over the picture to see the final color) Your goal is to deliver the exact volume needed to reach the endpoint. When you have reached the end point, record the final volume in the buret (again to two decimal places) and calculate the volume of titrant delivered.
	Pour the titrated solution into the waste container, but don’t lose your stir bar.
Part 3: Titration of a low temperature, saturated Ca(OH)2solution
	Add about 100 mL of distilled water to a 250 mL beaker. Place it in a salted ice bath for at least 5 minutes. Add solid Ca(OH)2 with constant stirring until the salt no longer dissolves.
	Remove the flask from the ice bath and measure the temperature of the cold solution.
	Using a funnel, quickly strain this solution through qualitative filter paper into a clean, dry 125 mL Erlen-meyer filter flask. Note: Only filter small amounts of solution at a time to avoid "swamping" the filter paper.  The filtrate solution should be clear when filtration is complete.  A "cloudy" filtrate indicates the presence of particulates that will throw off the titration results.  Re-filter any "cloudy" filtrates until they are clear.
	Pipet 10.00 mL of this clear solution into another clean, dry 100 mL Beaker. Add approximately 25 mL of distilled water and 10-12 drops of the bromothymol blue indicator. Gently slide a magnetic stir bar into the flask.
	Set the flask on the stirrer and begin stirring at a gentle rate. (Make sure there is no splashing of the solution.) Record to two decimal places the beginning volume level of HCl in the buret.
	Begin the titration, allowing the titrant to fall from the buret at a rapid drop-by-drop pace. During this addition, the initial blue color will begin to turn green and then yellow. The end point is reached when the entire solution turns yellow. (Run your mouse over the picture to see the final color) Your goal is to deliver the exact volume needed to reach the endpoint. When you have reached the end point, record the final volume in the buret (again to two decimal places) and calculate the volume of titrant delivered.
	Pour the titrated solution into the waste container, but don’t lose your stir bar.
Part 4: Titration of a ? temperature, saturated Ca(OH)2solution
	Based on your calculation of the molar solubility of the Ca(OH)2 solution at low, room and high temperature choose another temperature at which to run the titration. Follow the same procedure as in parts 1-3.