Gravimetric Materials Essay

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Gravimetric Materials | 1. Precipitation Gravimetry | Equipment | Diagram | Reaction | Description / Purpose | a. Suction Flask / Büchner flask | | | * Büchner flask (also known as a vacuum flask, filter flask, side-arm flask or Kitasato flask) is a thick-walled Erlenmeyer flask with a side arm to which a vacuum can be applied. | b. Büchner funnel | | | Büchner funnel is one device used for pressure assisted filtration. Buchner funnel is a cylindrical porcelain filtering funnel (glass and plastic funnels are also available) that has a perforated plate on which the flat filter paper is placed. A vacuum in the flask underneath the filter allows atmospheric pressure on the sample to force the liquid through the filter paper. It is named after the German chemist Ernst Wilhelm Büchner (1850-1925) who designed this funnel in 1885. | c. Sintered Glass crucibles | | * Used to filter the silver chloride precipitate (or other solid) from its parent liquid | Generally, a piece of ashless filter paper in a fluted funnel, or a filter crucible is used for filtration. In place of filter paper a crucible can be used whose bottom is made of some porous material, like sintered glass or porcelain. These crucibles are chemically inert and mechanically stable at high temperatures. | 2. Volatilization Gravimetry | d. Silical Crucible | | | Composed of pure fused silica, ideal for applications where other materials areunsuitable. It has a very low co-efficient of thermal expansion, which allowsrapid heating and cooling with virtually no risk of thermal breakage. Silica is inert to most substances, including all acids regardless of concentration ortemperature, except hydrofluoric acid, phosphoric acid (over 200°C) alkalis andsome metal oxides (over 800°C). Transparent silica ware offers easier viewing ofprocesses and reactions

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