CHM 100 – Introduction to Chemistry

Experiment # 16 – Analysis by Precipitation…Revised…

Objectives:       Make a solution of Na₂CO₃

React it with 0.5M CaCl₂

Determine the percent yield of CaCO₃ product

Reaction:          Na₂CO₃ (s) + CaCl₂ (aq)   →   CaCO₃ (s) + 2 NaCl (aq)

Procedure:

1. Tare a clean 250mL beaker

2. Add between 1.20g – 1.40g of Na₂CO₃ to the beaker (data table #1)

3. Add approximately 25mL of distilled H₂O and stir until the solid dissolves

4. Add 50.0mL 0.5M CaCl₂ solution (data table #2)

6. Assemble a filtering apparatus.  You will need a ring stand, iron ring, clay triangle, funnel, beaker to collect your filtrate, and filter paper to collect the CaCO₃ product.

7. Weigh 1 disc of filter paper (data table #3).  Fold this filter paper into a cone by folding it in half and then folding it in half again, the second fold with a slight offset.

8. Place the pointed end of the filter paper into the bottom of funnel.  Separate the filter paper so there are 3 layers of filter paper on one side and 1 on the other.  Wet the filter paper with a little distilled H₂O.

9. Carefully pour your solution through the funnel in portions.  Do NOT overfill the funnel.  To make certain you get all the CaCO₃ out of your beaker into the funnel, you may rinse your beaker with cold distilled H₂O.

10. If your filtrate is cloudy, you should re-filter.

11. When the filtration is complete, weigh and label a watchglass (data table #4).  Place your filter paper containing CaCO₃ on the watch glass and leave to dry as directed by your instructor.

12. Your instructor may have you do a 2^nd trial.

*** Please return this sheet to your lab instructor at the end of the lab. ***

***  Thank you!  ***