1. Percent Oxygen in a Potassium Compound Determination of the Formula of a Potassium Compound based on its Composition.

2. Purpose l To experimentally determine the percent oxygen and identify an unknown compound.

3. Concept l Quantitative analysis is a chemical principle that allows chemists (and others) to experimentally determine the composition of chemical compounds l Application is left to the student.

4. Safety l NameHFRSpecial l KClO ? 203Oxidizer l MnO 2 202 Burns Skin l Be aware that the hot test tube looks like a cool test tube. l Check all equipment before handling.

5. Procedure.1 l Obtain a clean test tube and add a pinch of manganese dioxide (MnO 2 ). Mass the test tube and MnO 2 and record.

6. Procedure.2 l Use a scoopula to slide about one gram of the potassium compound into the test tube. This is done to minimize the amount of chemical being stuck on the sides of the test tube.

7. Procedure.3 l Mass the test tube containing the MnO 2 & potassium compound mixture and record. l Carefully agitate the mixture. To create an even mixture.

8. Procedure.4 l Set up the test tube nearly horizontal using a utility clamp. l Gently heat the lower end of the test tube. The mixture will appear to “boil” as it releases oxygen gas.

9. Procedure.5 l When the bubbling subsides, heat the test tube more strongly. Eventually the hottest flame is used. Heat strongly for at least ten minutes. If the test tube begins to ‘smoke’ it is losing potassium compound. Notice the ‘smoke’

10. Procedure.6 l Shut off the burner and allow the test tube to cool. l Mass the test tube and product and record. l Clean up the lab station.

11. Data Table l Mass of TT & MnO 2 _____________ l Mass of TT, MnO 2 & unknown_____________ l Mass of unknown compound_____________ l Mass of TT & product_____________ l Mass of oxygen lost_____________ l Percent oxygen lost_____________

12. Calculations.1 l The unknown compound is one of the following compounds. Calculate the percent oxygen in each of these compounds. l KClO 4 l KClO 3 l KClO 2 l KClO

13. Calculations.2 l Identify the compound used in this experiment.

14. Conclusion l A good conclusion will include A summary of the procedures. The results of the experiment Sources of error A propagation of error