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Example of Lab Report: Decomposition of Potassium Chlorate

Calculate and record the following for the experiment performed with 10.000 g KClO3
1. (a) mass of the crucible with manganese(IV) dioxide (in grams) = 53.300g

(b) mass of the crucible after potassium chlorate has been added (in grams) = 63.300g

(c) mass of the crucible after heating (in grams) = 59.383g

(d) mass of potassium chloride (in grams) = ?

(e) mass of oxygen in sample of potassium chlorate (in grams) = ?

(f) mass percent of oxygen in potassium chlorate = ?

2. Calculate the percent error for this second experiment using the experimental and theoretical values (from previous calculation) of the mass percent of oxygen.

3. Now calculate the average mass percent of oxygen in potassium chlorate using your two experimental values

4. Calculate the percent error using your average value. Is it lower than either of your individual experiments

5. How well do your experimental results match the theoretical value? What sources of error may explain the discrepancy

6. In an actual lab setting, students do not have access to the "Data Window" that you used to determine that the reaction was complete (and you only had KCl left in the crucible. Instead, students would rely on a procedure called weighing to a constant mass, which includes weighing and reheating the crucible several times. Explain how you think this might work

7. How else might a student in an actual lab be able to determine when the reaction is complete

8. If potassium chloride "smoke" had been lost during the heating of the crucible, would this have made the calculated percent oxygen too high or too low? Explain, using a calculation to illustrate your reasoning

9. Imagine that you can create potassium chlorate (KClO3) from a reaction involving potassium metal, chlorine gas and oxygen gas. In the lab, you are able to measure the amount of K, Cl, and O that are used in the reaction so that you can determine the percent oxygen in potassium chlorate. What would you expect to find for the percent oxygen in potassium chlorate? Explain your answer.

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Solution Summary

Detailed calculations are shown for experimental percentage of oxygen in KClO3. Error claculations are also outlined. Sources of error and other pertinent questions are discussed.