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Homework Help: Chem Lab: Separation and Identification of a Metal chloride from an organic substance

  1. Nov 7, 2009 #1
    1. The problem statement, all variables and given/known data
    Project 7: Identification and Separation of a Metal Chloride and an Organic
    Here is an open ended lab we have to do for general chemistry:

    A chemical manufacturing company which produces a variety of specialty
    chemicals has come across an old waste jar with an illegible label during a lab clean-up. In order to properly dispose of the material, the company needs to identify the components and determine the percent composition, by weight, of the mixture in the jar. They know that the waste contains two different chemical compounds that are both solids at room temperature. One of the components is one of the following metal chloride salts:
    CuCl2•2H2O or CoCl2•6H2O
    Note that these are hydrates. You must take this into account when
    calculating molar mass. The other component is one of the following organic substances:
    starch (162.14 g/mol), cholesterol (386.66 g/mol) or
    phenyl benzoate (198.22 g/mol)

    Your group has been assigned to separate, identify and weigh the two
    components. In addition, your group must use one other method to determine the mass percent of one of the components in the mixture in order to check the results. The following wavelengths are appropriate for a spectrophotometric determination: CuCl2•2H2O 650 nm
    CoCl2•6H2O 510 nm
    When using a spectrophotometer, it is best to prepare dilute solutions such that the absorbance measured is less than 1.000.

    Hints and other important information for Projects 7
    Pieces of equipment and chemicals which are available that might be of use include:
    "standards" (starch, cholesterol, phenyl benzoate, Mg(OH)2, Ca(OH)2,
    CuCl2•2H2O, CoCl2•6H2O)
    25 mL burets
    5 mL, 10 mL and 25 mL pipets
    50 mL, 100 mL and 250 mL volumetric flasks
    organic solvents: acetone, ethanol, hexane (these solvents, especially hexane, are
    methyl red
    dried potassium acid phthalate
    dried sodium carbonate

    2. Relevant equations

    3. The attempt at a solution
    I was looking for some help on what procedures to use or tests to identify the substances and therefore determining mass percent. I was thinking solubility but don't know how to separate the liquids at first. Spectrophotometry is also an option but how do I dilute the solution to under 1.000 absorbance? I have some ideas but it would be greatly appreciated if anyone could give me some info. Thanks a lot!!
  2. jcsd
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