Analytical Chemistry

Solubility-Product Constants (Chemical Equilibrium)

  Solubility-Product Constants ** Most, but not all, sparingly soluble salts are essentially completely dissociated in saturated aqueous solution.  ** For example, when an excess of barium iodate is equilibrated with water, the dissociation process is adequately described by the equation:   Using Equation:     we write:     …

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Dilution of Solutions

  Dilution of Solutions   ** Concentrated solutions are often stored in the laboratory stockroom for use as needed. Frequently we dilute these “stock” solutions before working with them.  ** Dilution is the procedure for preparing a less concentrated solution from a more concentrated one. ** Suppose that we want …

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Chemical Stoichiometry

  Chemical Stoichiometry ** Stoichiometry is the quantitative relationship among the amounts of reacting chemical species. ** This subject provides a brief review of stoichiometry and its applications to chemical calculations. ** The stoichiometry of a reaction is the relationship among the number of moles of reactants and products as …

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Solutions and Their Concentrations

    ** Over the course of history, measurements and their corresponding units were invented at the local level. By necessity of primitive communication and local technology, standards were nearly nonexistent, and conversions among the many systems were difficult. The result was many hundreds of distinct ways of expressing concentrations …

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Safety in the laboratory

  Safety In The Laboratory There is necessarily a degree of risk associated with any work in a chemical laboratory.  Accidents can and do happen. Strict adherence to the following rules will go far toward preventing (or minimizing the effect of ) accidents: (1)Before you begin work in any laboratory, …

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The Laboratory Notebook

  The Laboratory Notebook   ** A laboratory notebook is needed to record measurements and observations concerning an analysis. ** The book should be permanently bound with consecutively numbered pages (if necessary, the pages should be hand numbered before any entries are made). ** Most notebooks have more than ample …

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Calibrating Volumetric Glassware in the laboratory

  Calibrating Volumetric Glassware   ** Volumetric glassware is calibrated by measuring the mass of a liquid (usually distilled or deionized water) of known density and temperature that is contained in (or delivered by) the volumetric ware. ** In carrying out a calibration, a buoyancy correction must be made since the density …

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Measuring Volume by Volumetric Flasks

  Volumetric Flasks ** Volumetric flasks are manufactured with capacities ranging from 5 mL to 5 L and are usually calibrated to contain (TC) a specified volume when filled to a line etched on the neck.      ** They are used for the preparation of standard solutions and for the dilution …

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Measuring Volume by pipets

Pipets ** Pipets permit the transfer of accurately known volumes from one container to another. ** Common types are shown in Figure (1), and information concerning their use is given in Table (1).    Table (1) ** A volumetric, or transfer, pipet (Figure 1a) delivers a single, fixed volume between 0.5 and 200 …

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Measuring Volume by Burets

Burets ** Burets, like measuring pipets, make it possible to deliver any volume up to the maximum capacity of the device. The precision attainable with a buret is substantially greater than the precision with a pipet. ** A buret consists of a calibrated tube to hold titrant plus a valve arrangement by …

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Filtration and Ignition of Solids

  Several techniques and experimental arrangements allow solids to be filtered and ignited with minimal contamination and error. (1) Apparatus (a) Simple Crucibles   ** Simple crucibles serve only as containers. Porcelain, aluminum oxide, silica, and platinum crucibles maintain constant mass—within the limits of experimental error— and are used principally to …

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