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Name:_____________________________________ Date:________ The Decomposition of Potassium Chlorate Safety: Wear goggles at all times and be careful not to touch hot equipment. Purpose: Perform a decomposition reaction, measure the remaining solid product and compare the experimental yield to the theoretical yield. Materials: Balance Clay triangle Ring stand and ring Bunsen burner Tongs Forceps Clean crucible and lid **Do not put a hot crucible in cool/cold water. Procedure: 1. Use tongs to hold clean, dry crucible over flame for 2 minutes. If the crucible appears to be turning black, adjust the Bunsen burner to prevent this and clean the crucible before continuing. Allow heated crucible to cool. Do not touch crucible or lid with your hands after this step. Weigh an empty crucible and cover. Record in data table. 2. Add ~2 grams of KClO3 and partially cover with crucible lid. Record exact mass in data table. 3. Heat for 15 minutes with equipment set up as shown. The texture of the reactant should visibly change. Do not lean directly over the crucible. 4. While the potassium chlorate heats, calculate the expected yield of solid product and write a hypothesis to state the expected mass of KCl. 5. Allow to cool. Handle crucible only with tongs. 6. Reweigh. Record in data table. 7. Calculate the weight of product. Data Table: Weight of empty crucible and cover Weight of crucible, cover and KClO3 sample Weight of KClO3 sample before heating Weight of sample, crucible, and cover after heating Weight of the sample only- after heating Rev. 1 Analysis and Results Show work for credit! 1. Reaction: Write the balanced chemical equation for this reaction. Include the state of matter. (For example, KClO3(s) indicates the potassium chlorate is solid phase) 2. Stoichiometric calculations for theoretical yield: (Include the formula for the product.) 3. Percent Yield: Percent yield = actual yield theoretical yield x 100% Percent yield = ___________________________ Conclusion Write a conclusion related to your hypothesis. Explain possible explanations for the difference between actual and theoretical (expected) yield Post-Lab Questions 1. Write the balanced equation for the decomposition of sodium chlorate. 2. Write the balanced equation for the decomposition of calcium chlorate. 3. Look at the products of these reactions. How did you know which product was in the crucible after heating? Rev. 1