Determining concentration of limewater [ Ca(OH)2] Solution

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Determining concentration of limewater [ Ca(OH)2] Solution

Calcium hydroxide, Ca(OH)2, is an ionic solid that is slightly soluble in water. A saturated solution (dissolved in water) is an equilibrium, that can be represented by the following equation:

Ca(OH)2(aq) + 2HCl (aq)? 2 H2O(l) + CaCl2(aq)

In this plan, I will design and collect the data that will allow me to calculate accurately the concentration of Ca(OH)2 from a volume of the solution.

The hydroxide ions formed when Ca(OH)2(s) dissolves can be measured by titration with an acid. From the balanced equilibrium equation, we can see that we do not need to measure the Ca2+ ions, since they are equal to one half of the concentration of OH- ions. An acid-base titration is a process in which a measured volume of an acid or base is added to a reaction mixture until some acid-base indicator changes color. In the procedure used in this lab, a dilute solution of HCl is titrated with a saturated solution of Ca(OH)2 to the endpoint of phenolphthalein.
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Apparatus:

* burette

* pipette / pipette filler

* 250ml volumetric flask

* 250 ml of saturated Ca(OH)2 solution

* Distilled water

* funnel

* Clamp / white tile

* conical flasks X 2

* phenolphthalein indicator / methyl orange indicator

* about 250 ml of 0.1M HCl solution, which I will distill myself from a 2M concentration.

* beaker

Safety Precautions:

While the concentrations used in this experiment are not large, acids and bases are both corrosive, and must ...

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