This experiment makes use of several types of volumetric glassware, specialized pieces of glassware which are used to measure volumes of liquids very precisely in quantitative laboratory work. Examples of these types of glassware include graduated cylinders, burettes, pipets, and volumetric flasks. These are carefully manufactured and expensive items and should be treated with great care. Ordinary beakers and flasks are not used for accurate volume measurements; the markings on these pieces of glassware are generally only accurate to within 5%.
Each piece of volumetric glassware is marked with its total volume, the notation TD or TC, and a temperature (usually 20°C). The marked temperature indicates the temperature at which the apparatus was calibrated. Since density and volume change with temperature, the volume markings are strictly correct only at the calibration temperature. The notations TD and TC stand for the phrases "to deliver" and "to contain." The TD notation, used on burettes and pipets (and some graduated cylinders), means that the apparatus is calibrated to accurately deliver or transfer the stated volume to another container. The TC notation, used on volumetric flasks and (most) graduated cylinders, means that the markings give an accurate measure of the volume contained, but that pouring the liquid into another container will not necessarily deliver the indicated volume.
Most solutions form a curved surface when placed in a glass container. This surface is called a meniscus and, in the case of aqueous solutions, is concave when viewed from above. To correctly read the level of liquid in a piece of glassware, it is important that your eye be on the same level as the surface of the liquid in order to avoid parallax errors.
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