Basic Tools and Lab Safety

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INTRODUCTION TO LABORATORY SAFETY The objectives of this introductory laboratory course are: To familiarize you with the basic principles of laboratory work and safety in the laboratory. To understand hypothesis testing using scientific methods. To analyze the data you have obtained and draw conclusions. To present the experiment, your data and conclusions in a clear and scientific fashion. 1. BASIC TOOLS AND SAFETY A. Laboratory Glassware Borosilicate glass is the most commonly used material for laboratory apparatus such as beakers, flasks, pipets, etc. It is stable to hot solutions and to rapid changes in temperatures. B. Volumetric Glassware Volumetric flasks are designed to contain an accurate volume at the specified temperature (20oC or 25oC) when the bottom of meniscus (the concave curvature of the upper surface of water in a column caused by capillary action or surface tension) just touches the marked "fill" line across the neck of the flask. Pipets are used to transfer a particular volume of solution.There are two common types: • Volumetric (transfer pipet) 100-0.5 mL. • Measuring pipet (serological pipet) 25-0.1 mL. Volumetric ones are used for accurate measurements, because they are designed to deliver only one volume. Measuring pipets, on the other hand, are marked at different volume intervals and they are not as accurate as volumetric pipets. Some graduated pipettes are "blow out" types. The final volume of solution must be blown out from the tip (A frosted ring near the top of pipets indicates that the last drop will be blown out). The others deliver a specific maximum volume from between the two lines that are farthest apart (Mohr type). Corrosive or toxic solutions must never be pipetted by mouth. -Micropipets: A variety of micropipets are available for measuring microliter volumes. -Burets: Their principal use is in

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