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2- lab 2-basic techniques - Chem 223 Experiment 2 PRACTICE...

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Chem 223: Experiment 2 PRACTICE WITH BASIC TECHNIQUES SAFETY FIRST! BRING AND WEAR YOUR GOGGLES ( This experiment completely follows the lab: “Practice with basic techniques”. Chem 223. UIUC) References : C, Chap. 2. H4, H5 Chap. 2. S & W, Chap. 19. SWH, Chap. 30. I. Purpose of the experiment The Multi-technique Operations, Pipette Calibration and Weighing by Difference exercises discussed on the following pages will introduce you to some basic operations you will need to perform in later experiments. These simple measurement experiments give you practice in pipetting, using the balance, and using your laboratory notebook. Careful attention to detail in this experiment will inculcate good laboratory technique, which will be crucial in obtaining accurate results in the later laboratories. Since a large fraction of your grade depends on accuracy, this lab offers an important opportunity to practice. Think of it as spring training for analysts! II. Before You Start the Lab ± Review the Balance Tutorial before you come to lab! ± When you arrive at the lab you will be assigned a lab bench and equipment locker, a combination for your desk, and an equipment checklist. Check to see that you have all the listed equipment and that it is not cracked, chipped or otherwise useless. ± Become acquainted with safety devices, such as the showers. Sign and turn in a set of laboratory regulations, if you have not already done so. ± You will be given cards to fill out. Fill these out and return them. ± You will be assigned to a balance. Meet the other people also assigned to that balance. It is your responsibility to keep the balance clean - you will be penalized if you abuse it. Each section will be given a demonstration on how to use the balance. You may not use any balance other than the one to which you are assigned without the TA’s permission. ± You should scrupulously clean the equipment you need for next week with detergent solution. Rinse with tap water and then three times with deionized water. Cleaning solution should be used only if detergent solution does not do the job. Go easy on the detergent. It does not take much. ± Clean out your desiccators, if the desiccant appears wet or is clumped (or check with TA). To open desiccator, slide the top off. Dump the old CaCl2 into the specially marked container in the lab. If the desiccator looks dirty, clean it and dry it well. Remove the old petroleum jelly with a paper towel. Grease on the inside may require acetone for removal. Add only about two 50 mL beakers full of the desiccant (CaCl2) to your desiccator. Regrease the rim and lid and remove any excess. Keep it closed.
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III. Multi-technique Operations III.A. Quantitative Transfer ± Using the top loading balance and a 50 mL beaker, weigh out about 2.5 g of either NaCl or KCl.
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