Lab 6D

Experiment 6D--Determining the Limiting Reactant and % Yield in a Precipitation Reaction

Objectives-

• To observe the reaction between solutions of sodium carbonate and calcium chloride
• To determine which of the reactant is the limitng and which is the excess reactant
• To determine the theoretical mass of precipitate that should form
• To compare the actual mass with the theoretical mass of precipitate and calculate the percent yield

Supplies-

Equipment

• centigram balance
• two 25mL graduated cylinder
• beacker (250mL)
• wash bottle
• safety goggle
• filtering apparatus
• ring stand
• 250 mL funnel
• filter paper
• lab apron
  
• safety goggles

By the way, the filtering apparatus should be set up like this.

Chemical Reagents

• 25 mL of 0.70 M sodium carbonate solution
• 25 mL of 0.50 M calcium chloride solution

Procedure:

Day1:

1. Put on lab coat and goggles
2. Obtain two 25 mL graduated cylinder and a 250 mL beaker
3. Measure 25 mL of sodium carbonate and calcium chloride solution.
4. Pour them each into the 25mL graduated cylinder.
5. Combine the two chemicals by pouring them both into the 250 mL beaker. Wait for 5 minutes while observing what happens.  Record the observations.
6. Write your names on the filter paper and then weigh the filter paper. Set up the filtering apparatus while waiting
7. Use a wash bottle to wet the bottom of the filter paper to keep it in place
8. Stir the newly mixed chemical into the filter as it filters the liquid into the beaker. Wait for the filtering to be completed.
9. Once all filtered, take the filter paper our and place it on a paper towel to dry.
10. Remember to clean up and wash your hands once you are done on day one of the experiment.

Day 2:

1. Weigh and record the precipitation from the chemicals from day 1.

Conclusion:

To find the results of the lab, we did the following calculations:

1. Measured the amount of CaCO3 produced by our experiment in grams with a centigram.
2. Balance the equation 1Na2CO3 + 1CaCl2 ---> 2NaCl + 1CaCO3
3. Calculate the theoretical yield using stoichiometry
4. Calculated the percent yield for the experiment
5. % yield = experimental result / theoretical yield * 100%

So, the result depends on the experimental outcome (the mass of the precipitation).  Therefore, each group will get slightly different answer.  However, the overall result should be approximately 90-95%.