In order to conduct experiments successfully, you must avoid contaminating the chemical reagents you use or reagents that will be used by other students after you. The following procedures will help minimize the possibility of contamination:
1. Wash all glassware that you will be using during the experiment at the start of class. Use tap water and soap followed by a rinse of tap water. The FINAL RINSE must use deionized or distilled water. Failure to do this final rinse may cause your experiment to fail due to traces of chemicals that are in tap water being left behind on your 0.
2. Avoid handling more than one reagent bottle at a time, so you don't interchange their stoppers or eye droppers by mistake.
3. When selecting a reagent bottle, read the label twice to be sure you have the chemical you want. Some of the experiments you will be doing involves using chemicals with names that are almost identical.
4. Do not lay the tops of reagent bottles or the eye droppers on the lab bench.
5. Use the separate spatulas or scoopulas that are provided to remove different solid chemicals from their bottles. Do not under any circumstance use your scoopula. Using a scoopula or spatula that has not been cleaned correctly contaminates the chemical for the entire class.
6. Never remove a liquid reagent from a stock bottle with your eye dropper. Use the eye dropper that is provided to transfer the liquid to your glassware, then at your work area you can use your eye dropper to transfer the liquid from the glassware. You do not want to contaminate the entire bottle of liquid reagent with an improperly washed eye dropper.
7. When a quantity of a chemical is removed from its original container, whether solid or liquid, DO NOT return any excess to the stock bottle. Ask around the lab to see if anyone needs some of the chemical. If no one needs it, dispose of the unused portion as directed by your lab instructor.
8. Never weigh a chemical directly on the balance. Use a preweighed container.
9. Never leave a stock bottle uncovered. Be sure to cover the bottle with the proper cover. Failure to cover solid chemicals can result in the chemical becoming hard due to moisture in the air or a chemical change may occur. Liquids can evaporate changing the concentration or a chemical change may occur.
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