Experiment 1: Gravimetric Analysis with Calcium Chloride andPotassium Carbonate
In this experiment, proper analytical experimental techniques willbe utilized to perform a double displacement reaction. A solutionwill be prepared containing a known quantity of calcium chloride.Then, the mass of calcium present will be determined through acareful precipitation of calcium carbonate. You will alsoinvestigate the hygroscopic nature of calcium chloride through acomparison reaction.
Materials:
Scale250 mL Beaker50 mL BeakerStir rod4.0 g Calcium chloride,CaCl25.0 g Potassium carbonate, K2CO3100 mL GraduatedCylinderPipetteRing for ring standRing stand

Funnel250 mL Erlenmeyer flask2 Filter papersWatch glassWeighboat*170 mL Distilled water*10 mL Isopropyl alcohol
*You must provide



Procedure
Place the weigh boat on the scale and determine its mass.
Add approximately 2.0 g of CaC to the weigh boat (the total massshould be     the mass of the weigh boat plus2.0 g). Set this sample aside, and let it sit exposed to the air(but otherwise undisturbed) for 24 hours. Complete Steps 3 - 20while you wait..
Place a 250 mL beaker on the scale. Tare the scale and leave thebeaker on the scale..
Add approximately 2.0 g. of CaCl2 to the beaker. Record the exactmass of the powder in Table 1.
Remove the beaker from the scale. Use a pipette to add 50 mL ofdistilled water to the beaker and mix with the stir rod until allCaCl2 has dissolved.
            Note: This is an exothermic process, so the beaker may becomewarm.
Place a 50 mL beaker on the scale. Tare the scale and leave thebeaker on the scale.
Add 2.5 g of K2CO3. Record the exact mass of the powder in Table1.
Remove the beaker from the scale. Use a pipette to add 25 mL ofdistilled water   to the 50 mL beaker and mix with thestir rod until all K2CO3 has dissolved.
Add all of the K2CO3 solution to the beaker containing the CaCl2solution. It is important that all of the K2CO3 is added. To ensurethis, rinse the 50 mL beaker with up to 5 mL distilled water, andpour the rinse in the CaCl2 solution.
Stir the solution for approximately four minutes. Then, allow it tosit for 15 minutes. This gives sufficient time for all CaCO3 toprecipitate.
While the solution is sitting, set up the filtration apparatus.Begin with an iron ring and a ring stand. Secure the ring to thestand. Be sure to select the ring size that most appropriatelyholds the funnel.
Place a funnel in the ring, and place a 250 mL Erlenmeyer flaskbelow the ring, such that the bottom of the funnel is also insidethe mouth of the flask.
Obtain a piece of filter paper. Use the scale to weigh the filterpaper and record the mass in Table 1.
Obtain a watch glass. Use the scale to weigh the watch glass andrecord the mass in Table 1.
Fold the filter paper in half and in half again, so that itresembles a triangle with one arced side.
Pull apart one fold of the filter paper so that three sides of thefilter paper remain together, with one side making up the otherhalf of the funnel shape.
Place the paper into the funnel and seat with a small amount ofdistilled water (this will prevent the filter paper from risingup).
Filter the solution from the beaker (that you created in Step 9)slowly. Additional distilled water may also be used to transfer anyremaining solid into the filtration apparatus.


After all the solution has been filtered, use the pipette to rinsethe filter paper with approximately 5 mL of isopropyl alcohol toaid the drying process. Allow the isopropyl alcohol to completelydrip through the filter before removing filter paper from thefunnel.
Carefully remove the filter paper, unfold and place itprecipitate-side up onto the pre-weighed watch glass. Be sure notto lose any product during this transfer.
Repeat Steps 3 - 20 for the CaCl2 that was allowed to sit exposedto air for 24 hours.
Allow the products from both trials to dry, undisturbed, for atleast 24 hours and determine the mass of the product recovered byre-weighing the system and subtracting the weight of the filterpaper and watch glass. Record your data in Table 1.

Table 1: Data and Observations
Substance
Trial 1
Trial 2
Mass of CaCl2:
 
 
Mass of K2CO3:
 
 
Mass of Filter Paper


Mass of Watch Glass


Mass of Product


Amount of Time Beaker Solution Stirred:


Amount of Time Beaker Solution Set:


Experimental Observations:







Calculations

First Trial

Theoretical yield (CaCO3):

Actual yield (CaCO3):

Percent yield:

Moles of Ca present in original solution, based on actualyield:

Mass of CaCl2 present in original solution, based on actualyield:
Second Trial

Theoretical yield (CaCO3):

Actual yield (CaCO3):

Percent yield:

Moles of Ca present in original solution, based on actualyield:

Mass of CaCl2 present in original solution, based on actualyield