Ksp by Titration Lab Sunday, November 01, 2015

General (you will be using a strong acid…use goggles!) You will create a new compound Ca(IO 3 ) 2 You will filter it to get a pure, saturated solution You will titrate the solution to find the IO 3 1- moles (and since you know volume, the concentration) From the IO 3 1- concentration, you should be able to calculate the Ksp for Ca(IO 3 ) 2

The set up Buret w/ S2O3 Filter CaCl2 NaIO3 20 mL dH2O HCl Starch KI Erlenmeyer Flask

Make the Ca(IO 3 ) 2 Pour 40 mL CaCl2 into 40 mL KIO3 You will NOT SEE a ppt It is very fine.

Filter the Ca(IO 3 ) 2 Slowly pour the Ca(IO3)2 into The filter paper You will be collecting the filtrate in a fresh beaker

Prepare for Titration Transfer 5 to 10.0 mL of the filtrate from Part I, above, with a graduated cylinder into a clean Erlenmeyer flask. Add about 20 mL of deionized water to the flask.

Prepare for Titration 3) Add 20 drops of 1 M HCl and mix thoroughly. The solution should take on a brown color. Swirl the solution to mix the KI 1) Dissolve about 2 g of solid KI in the solution

Titration Titrate the mixture with the K 2 S 2 O 3 until the brown color changes to yellow. (SLOW DOWN the titration!!!) The exact color of yellow does not matter

Titration 1) Add several drops of starch to the solution, enough to turn the solution black. 2) Continue titrating with the K 2 S 2 O 3 until the blue/black color just disappears.

You need to have recorded Volume of Ca(IO 3 ) 2 solution (5-10 mL) Volume of the K 2 S 2 O 3 solution used in titration

Disposal All chemicals can be flushed down the sink with a lot of water Rinse out the burets with dH2O and leave them in the back Rinse out all glassware and leave in back