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:
- Put on lab coat and goggles
- Obtain two 25 mL graduated cylinder and a 250 mL beaker
- Measure 25 mL of sodium carbonate and calcium chloride solution.
- Pour them each into the 25mL graduated cylinder.
- Combine the two chemicals by pouring them both into the 250 mL beaker. Wait for 5 minutes while observing what happens. Record the observations.
- Write your names on the filter paper and then weigh the filter paper. Set up the filtering apparatus while waiting
- Use a wash bottle to wet the bottom of the filter paper to keep it in place
- Stir the newly mixed chemical into the filter as it filters the liquid into the beaker. Wait for the filtering to be completed.
- Once all filtered, take the filter paper our and place it on a paper towel to dry.
- Remember to clean up and wash your hands once you are done on day one of the experiment.
Day 2:
- Weigh and record the precipitation from the chemicals from day 1.
Conclusion:
To find the results of the lab, we did the following calculations:
- Measured the amount of CaCO3 produced by our experiment in grams with a centigram.
- Balance the equation 1Na2CO3 + 1CaCl2 ---> 2NaCl + 1CaCO3
- Calculate the theoretical yield using stoichiometry
- Calculated the percent yield for the experiment
- % 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%.
