Part 1Lab Objective:Part 1-Experimentally determine the Ksp of Calcium Hydroxide

Warning: Calcium Hydroxide is a strong base, please use the hood for transferring the chemical. The solid powder will disperse easily, please be careful. It is caustic and should be removed immediately if the skin is exposed to the solid form. Rinse and have another student alert the instructor continue rinsing. Wear Goggles.

Pre-Lab (PL) Write the net ionic equation for the dissolution of Calcium Hydroxide in water.

-Recording the exact mass of calcium hydroxide here____________, place approximately .3gram calcium hydroxide in a 100.0ml volumetric flask. (make sure the value is between .250 and .350grams)

-Add water until the solution is 100.0ml. Gently add a stir bar and using a stir-plate allow the solution to mix for several minutes to ensure the solution is saturated.

-Gently filter the calcium hydroxide through filter paper and funnel into a 250ml Erlenmeyer Flask. This may take a while as the fine solid will start to clog the paper. (this should be the last activity of day 1)

PL Assume the calcium hydroxide solution you will make is saturated. Draw a representation of the mixture in the filtrate. Show ions in significant concentrations. Show at least three waters oriented appropriately around each ion. The ions should show an appropriate ratio and with appropriate size.

Tomorrow you will be using bromothymol blue as your indicator. The acid and the base form are shown below.

PL Compare the conductivity and solubility (in water) of the acid and base forms of bromothymol blue. Justify your answers.

PL Read basic information on the indicator bromothymol blue. Based on this research, describe your expectations in terms of the initial color when you place the bromothymol blue in the solution as well as the color change you would see when the solution becomes acidic as a result of the addition of HCl.

-Add a drop or two of Bromothymol blue so that color in the solution is apparent. (you may want to place a white piece of paper below the Erlenmeyer Flask to make the color more visible)

PL Please watch this brief video on proper use of a Burette during a titration-https://www.youtube.com/watch?v=9DkB82xLvNE

-Titrate the Calcium hydroxide solution with the .10M HCl. Titrate slowly using no more than 4-8 drops per second. The moment you first perceive a localized color change in the Erlenmeyer Flask, cut the titration rate to about a drop per second and swirl between each drop. The titration process will take several minutes. Record the volume of HCl___________

PL Write the balanced equation for the neutralization of Calcium Hydroxide with Hydrochloric acid

PL Write the balanced net ionic equation for the reaction above

PL At the culmination of the titration, draw the composition of the solution assuming you have not added extra acid. Show ions in significant concentrations. Show at least three waters oriented appropriately around each ion. Show solids, if they exist. The ions should show an appropriate ratio.

PL If you inadvertently added some extra acid. Indicate the ions in significant concentration in the container shown.

Calculate the moles of hydrochloric acid used

Calculate the molarity of the Calcium hydroxide in solution prior to the addition of the hydrochloric acid

PL From the net ionic equation for the dissolution of Calcium Hydroxide into water, write an equilibrium expression

Calculate the experimental Ksp of Calcium Hydroxide

PL If the solubility of Calcium Hydroxide is listed as 1.7g/1000ml, calculate the theoretical Ksp of Calcium Hydroxide. (set up ice chart and convert calcium hydroxide to concentration)

The Explain any deviation between your experimentally determined Ksp and the theoretical Ksp.

PL Assume you initially weighed the filter paper and the paper had a mass of .584grams. The paper is dried after being used as a filter for the Calcium Hydroxide and weighed again with the mass of .799grams. Using these values and your experimental mass of Calcium Hydroxide, calculate the Ksp of the Calcium hydroxide.

Part 2

ObjectivePart 2-Explain experimental results using common ion effect

-Add approximently the same mass of Calcium Hydroxide used in part I to a 125ml Eyrlenmeyer flask (in the hood). Place in 50.ml of water. Add the stir bar and agitate for several minutes as done in Part 1.Document observations

-Add 20.0ml of vinegar (containing acetic acid), or the directed acid, and let mix for several minutesDocument observations

Rewrite the net ionic equation for the dissolution of Calcium Hydroxide.

Explain your observations using Lechatelier’s Principle and common ion effect.