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  COMMON LABORATORY APPARATUS   Beakers  are useful as a reaction container or to hold liquid or solid samples. They are also used to catch liquids from titrations and filtrates from filtering operations. Bunsen Burners  are sources of heat.  Burets  are for addition of a precise volume of liquid. The volume of liquid added can be determined to the nearest 0.01 mL with practice.  Clay Triangles  are placed on a ring attached to a ring stand as a support for a funnel, crucible, or evaporating dish. Droppers  are for addition of liquids drop by drop  Erlenmeyer Flasks  are useful to contain reactions or to hold liquid samples. They are also useful to catch filtrates.     Glass Funnels  are for funneling liquids from one container to another or for filtering when equipped with filter paper. Graduated Cylinders  are for measurement of an amount of liquid. The volume of liquid can be estimated to the nearest 0.1 mL with practice. Hot Plates  can also be used as sources of heat when an open flame is not desirable. Pipets are used to dispense small quantities of liquids. Ring stand with Rings  are for holding pieces of glassware in place. Test Tubes are for holding small samples or for containing ll - scale reactions.   Test tube holders are for holding test tubes when tubes should not be touched Tongs  are similar in function to forceps but are useful for larger items. Volumetric Flasks  are used to measure precise volumes of liquid or to make precise dilutions. Wash bottles  are used for dispensing small quantities of distilled water. Watch glasses  are for holding small samples or for covering beakers or evaporating dishes. Wire Gauze  on a ring supports beakers to be heated by Bunsen burners   . LABORATORY EQUIPMENT Dilution mark   Balances  are used to determine the mass of a reagent or object. Spectrophotometers  are used to measure the absorbance or transmittance of a liquid sample. Fume Hoods  are used to ventilate noxious or harmful gases.  COMMON LABORATORY TECHNIQUES  In all volumetric glassware (pipet, buret, volumetric flasks, graduated cylinder, etc.), it is necessary to read the level of a liquid. A liquid in a small-diameter container will form a meniscus  or curve at the surface of the liquid. Usually this meniscus curves downward to a minimum at the center. To read the level of the liquid properly, the eye should be at the same level as the bottom of the meniscus. Sometimes a white card or a white card with a black mark on it will help a person to see the meniscus clearly. For volumetric flasks and transfer pipets, the volume of the glassware is exact when the bottom of the meniscus is even with the etched line. In a graduated cylinder or a buret, the volume is read from the graduations etched on the glass. To read the volume correctly, visualize the distance between the tenths of milliliter marks as divided into ten equal amounts. The volume is then found by reading the number of tenths of milliliters and estimating hundredths of milliliters. The reagents used by all of the students can be contaminated by one careless student. Never put anything back into the reagent bottle . A certain amount of liquid can be obtained in several ways. 1) Pour from the reagent bottle into a beaker and draw up the liquid into a pipet from the beaker. 2) Pour from the beaker into a graduated cylinder to within 0.1 ml of the desired amount, adding the last drop with an eyedropper filled from a beaker. Only use appropriately labeled spatulas for each reagent bottle. Pour the solid into a beaker, onto weighing paper, or into a weigh boat. Never pour excess back into the bottle. Reagents are to remain on the plastic on the center bench. This will 1)prevent spills and accidents from occurring at your work area, 2)save time for everyone because all of the chemicals will be relatively easy to find in a central location, and 3)make clean-up easier if a spill does occur. When you are finished using a chemical, replace the lid ! A mix-up of lids could also contaminate an expensive chemical. 100 90 91.7 Graduated Cylinder  47 46 46.33 Buret Reading a Meniscus Care of Reagents 6M NaOH Copper Sulfate
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