Gravimetric Analysis Flashcards
Are quantitative methods based on determining the mass of a pure compound to which the analyte is chemically related
Gravimetric Methods
The analyte is separated from a solution of the sample as a precipitate and is converted to a compound of known composition that can be weighed.
Precipitation Gravimetry
The analyte is separated from the other constituents of a sample by converting it to a gas of known chemical composition. The mass of the gas serves as a measure of the analyte concentration.
Volatilization Gravimetry
The analyte is separated by deposition on an electrode by an electrical current and the mass of this product provides a measure of the analyte concentration.
Electrogravimetry
The mass of a reagent of known concentration required to react completely with the analyte provides the information needed to determine the analyte concentration.
Gravimetric Titrimetry
Uses a mass spectrometer to separate gaseous ions formed from the elements making up a sample of matter. The concentration of the ions is determined by measuring the electrical current when they fall on the surface of the detector.
Atomic mass spectometry
Consists of solid particles with diameters that are less than 10^-4 cm.
Colloids
Contain tiny particles invisible to the naked eye (10^-7 to 10^-4 cm in diameter)
Colloidal Suspension
Describes a solution in which particles with dimensions on the order of a tenth of a millimeter or greater are temporarily dispersed in the liquid phase.
Crystalline solution
An unstable solution that contains a higher solute concentration than a saturated solution.
Supersaturated solution
The process by which a minimum number of atoms, ions, or molecules join together to give a stable solid.
Nucleation
A process by which a substance is held on the surface of a solid.
Adsorption
The retention of a substance within the pores of a solid.
Absorption
The process by which a coagulated colloid reverts to its original dispersed state.
Peptization
A process in which a precipitate is heated in the solution from which it was formed (the mother liquor) and allowed to stand in contact with the solution.
Digestion
A process in which normally soluble compounds are carried out of solution by a precipitate.
Coprecipitation
Common and can cause significant contamination of precipitates with large specific surface areas (i.e., coagulated colloids).
Surface adsorption
The filtered solid is redissolved and reprecipitated to reduce the contaminant concentration.
Reprecipitation
Defined as the surface area per unit mass of solid and usually has the units of square centimeters per gram.
Specific surface area
A contaminant replaces an ion in the lattice of a crystal.
Mixed crystal formation
A compound is trapped within a pocket formed during rapid crystal growth.
Occlusion
Crystals grow together and trap a portion of the solution in a tiny pocket
Mechanical entrapment
A process in which a precipitate is formed by slow generation of a precipitating reagent homogeneously throughout a solution.
Homogeneous precipitation
A process of recording thermal decomposition curves.
Thermogravimetric analysis
