Gravimetric Analysis and Professionalism Guidelines

These flashcards cover the fundamental vocabulary and concepts of Gravimetric Analysis, including types of methods, precipitate formation mechanisms, impurity types, and laboratory guidelines for medical technology students.

Gravimetric Methods

Quantitative methods based on determining the mass of a pure compound to which the analyte is chemically related.

Precipitation Gravimetry

A technique where the analyte is separated from a solution as a precipitate and converted to a compound of known composition that can be weighed.

Volatilization Gravimetry

A technique where the analyte is separated from other constituents of a sample by converting it to a gas of known chemical composition that can be weighed.

Electrogravimetry

A technique where the passage of electric current causes the deposition of metal upon a weighed inert electrode.

Colloidal Suspensions

Suspensions with particle diameters ranging from $10^{-7}$ to $10^{-4} ext{cm}$ that normally remain suspended and are very difficult to filter.

Crystalline Suspensions

Suspensions with particle diameters in the tenths of a mm or larger that normally settle out spontaneously and are readily filterable.

Nucleation

A mechanism of precipitate formation where individual ions, atoms, or molecules coalesce to form a stable solid nuclei.

Particle Growth

A mechanism of precipitate formation where ions, atoms, or molecules are added to a nucleus to form larger particles.

Supersaturated Solution

An unstable solution that contains a higher solute concentration than a saturated solution.

Von Weimarn Equation

An equation related to relative supersaturation (RSS) used to determine particle size, where Q is solute concentration and S is solute solubility.

Co-precipitation

A process where impurity is precipitated along with the desired precipitate, including surface adsorption, occlusion, inclusion, and mechanical entrapment.

Surface Adsorption

A source of contamination where the impurity is chemically or physically adsorbed onto the surface of precipitates; it is the major source of contamination in coagulated colloids.

Digestion

A process involving a waiting time where water is expelled from the solid to give a denser mass with a smaller specific surface area, or to expose occluded material to the supernatant solution.

Reprecipitation

A process where a filtered solid is redissolved and precipitated a second time to significantly lower the contaminant concentration.

Mixed-Crystal Formation

A type of coprecipitation in which a contaminant ion replaces an ion in the lattice of a crystal, such as $SrSO_4$ in $BaSO_4$.

Occlusion

A type of co-precipitation in which a compound (foreign ions in the counter-ion layer) is physically trapped within a precipitate during rapid formation.

Mechanical Entrapment

A type of co-precipitation in which a precipitate physically traps a pocket of solution during rapid formation.

Ascarite

A material composed of $NaOH$ on asbestos used in volatilization gravimetry to collect and weigh $CO_2$.

Group 17 Exceptions (PMS)

Specific ions that form precipitates with Group 17 elements: $Pb^{2+}$ (Lead), Mercury ($Hg_2^{2+}$), and $Ag^+$ (Silver).

Sulfate Exceptions (Castro Bear)

Specific ions that form precipitates with sulfates ($SO_4^{2-}$): $Ca^{2+}$, $Sr^{2+}$, and $Ba^{2+}$.

Bilirubin SI Unit Conversion Factor (CF)

The value used to convert $mg/dL$ to $ext{μmol/L}$, which is $17.10$.

Mixed crystal Formation

A type o f coprecipitation in which a contaminant ion replaces an ion

in the lattice of a crystal.

Occlusion

A type of co-precipitation in which a compound (foreign ions in the counter-ion layer )

is physically trapped within a precipitate during rapid precipitate formation.