Gravimetric Methods

Question 1

Quantitative techniques that determine the quantity of an analyte by measuring the mass of a pure compound chemically related to it.

Answer 1

Gravimetric Methods

Question 2

This method isolates or transforms the analyte into weighable substance.

Answer 2

Gravimetric Method

Question 3

Signal Measured: Mass of a dry, stable precipitate.
Example: Determination of Chloride, Sulfates, Phosphates and Metal Ions

Answer 3

Precipitation Gravimetry

Question 4

Signal Measured: Mass loss or gain due to release or absorption of a volatile component.
Example: Water content (Loss on drying), CO2 in Carbonates, ammonia, sulfur

Answer 4

Volatilization Gravimetry

Question 5

Signal Measured: Mass of material deposited on an electrode.
Example: Determination of metal such as Co, Ni, Pb from solutions

Answer 5

Electrogravimetry

Question 6

Signal Measured: Continuous change in mass with temperature or time.
Example: Decomposition analysis, moisture, and ash content thermal stability.

Answer 6

Thermogravimetric Analysis (TGA)

Question 7

Very small precipitate (1-1000 nm) or invisible.

Answer 7

Colloidal Precipitate

Question 8

Large precipitates, visible particles or crystals.

Answer 8

Crystalline Precipitates

Question 9

Foreign ions takes the place of ions in crystal lattice of the precipitate.

Answer 9

Inclusion

Question 10

Impurities become trapped inside a growing crystals during rapid formation.

Answer 10

Occlusion

Question 11

Impurities are physically trapped between particles or in the filter.

Answer 11

Mechanical Entrapment

Question 12

Impurities adhere to the surface of atmosphere.

Answer 12

Surface Adsorption

Question 13

Substitution of ions in a crystal lattice.

Answer 13

Mixed Crystal Formation

Question 14

Modern application of gravimetry, wherein the mass of a substance is continuously measured as it is heated over time.

Answer 14

Thermogravimetric Analysis (TGA)

Question 15

Mass changes due to loss of water.

Answer 15

Dehydration (TGA)

Question 16

Mass changes due to release of gases as CO2.

Answer 16

Decomposition (TGA)

Question 17

Loss or gain of mass due to the reactions with atmosphere

Answer 17

Oxidation or reduction (TGA)

Question 18

Major source of contamination in coagulated colloids, but not in crystalline precipitates.

Answer 18

Adsorption

Question 19

Best to purify impurities that is adsorbed by ppt.

Answer 19

Digestion and Washing

Question 20

Most accurate and precise methods of macro-quantitative analysis.

Answer 20

Gravimetric Analysis