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8.7: Chapter Summary and Key Terms

  • Page ID
    163754
  • Chapter Summary

    In a gravimetric analysis, a measurement of mass or a change in mass provides quantitative information about the analyte. The most common form of gravimetry uses a precipitation reaction to generate a product whose mass is proportional to the amount of analyte. In many cases the precipitate includes the analyte; however, an indirect analysis in which the analyte causes the precipitation of another compound also is possible. Precipitation gravimetric procedures must be carefully controlled to produce precipitates that are easy to filter, free from impurities, and of known stoichiometry.

    In volatilization gravimetry, thermal or chemical energy decomposes the sample containing the analyte. The mass of residue that remains after decomposition, the mass of volatile products collected using a suitable trap, or a change in mass due to the loss of volatile material are all gravimetric measurements.

    When the analyte is already present in a particulate form that is easy to separate from its matrix, then a particulate gravimetric analysis is feasible. Examples include the determination of dissolved solids and the determination of fat in foods.

    Key Terms

    coagulation

    definitive technique

    electrogravimetry

    ignition

    occlusion

    precipitant
    relative supersaturation

    surface adsorbate

    volatilization gravimetry

    conservation of mass

    digestion

    gravimetry

    inclusion

    particulate gravimetry

    precipitation gravimetry

    reprecipitation

    thermogram

    coprecipitate

    direct analysis

    homogeneous precipitation

    indirect analysis

    peptization

    quartz crystal microbalance

    supernatant

    thermogravimetry