Ch 35: Decomposing and Dissolving the Sample

Question 1

A resistant to heat and attack by strong chemical agents

Answer 1

Refractory substance

Question 2

When the sample treatment did not dissolve the sample completely because portions of the analyte are retained within the residue

Answer 2

Incomplete dissolution of the analytes

Question 3

Enumerate the sources of error in decomposition and dissolution

Answer 3

1. Incomplete dissolution of the analytes
   2.Losses of the analyte by volatilization
   3.Introduction of Analyte as a Solvent Contamination
   4.Introduction of contamination from reaction of the solvent with the vessel walls

Question 4

The possibility that some portion of the analyte may volatilize and be lost

Answer 4

Losses of the analyte by volatilization

Question 5

When the mass of solvent required to dissolve a sample exceeds the mass of a sample and when the analyte present is in trace amount or small concentration, which leads to significant error.

Answer 5

Introduction of Analyte as a Solvent Contamination

Question 5

An error encountered in decomposition that involved high-temperature fusions

Answer 5

Introduction of contamination from reaction of the solvent with the vessel walls

Question 5

An inorganic acid that is an excellent solvent for inorganic samples but it limited to decomposing organic materials.

Answer 5

HCl

Question 6

A process of oxidative decomposition of organic samples by liquid oxidizing reagents, such as HNO3, H2SO4, HClO4, etc

Answer 6

Wet ashing

Question 7

Is a strong oxidant that dissolves all common metals with the exception of aluminum and chromium

Answer 7

HNO3

Question 8

An effective reagent for decomposition as a solvent to its high boiling temperature, where most organic compounds are dehydrated and oxidized at this temp

Answer 8

H2SO4

Question 9

A potent oxidizing agent (has a potentially explosive nature) that when comes into contact with organic materials promotes violent explosions

Answer 9

HClO4

Question 10

More rapid wet ashing can be obtained by the use of mixture of acids

Answer 10

Oxidizing mixtures

Question 11

A mixture containing 3:1 of conc. HCl and HNO3

Answer 11

Aqua regia

Question 12

Use in the decomposition of silicate rocks and minerals

Answer 12

Hydrofluoric acid

Question 13

The usage of microwave for the decomposition of both organic and inorganic materials, the advantage is the speed of the process.

Answer 13

Microwave decompositions

Question 14

Microwave digestor that is constructed from low-loss materials that are transparent to microwaves that are thermally stable and resistant to chemical attacks

Answer 14

Moderate-pressure digestions

Question 15

A schematic of a commercial microwave bomb designed to operate at 80 atm that can be tolerated by the Moderate-pressure vessel

Answer 15

High-pressure microwave vessels

Question 16

a.k.a open-vessel system; does not have an oven but uses focused microwave cavity

Answer 16

Atmospheric-pressure digestions

Question 17

designed to heat simultaneously of the moderate-pressure vessel

Answer 17

Microwave Ovens

Question 18

Developed for performing fusions and for dry ashing samples that contains organic materials before acid dissolution

Answer 18

Microwave furnaces

Question 18

The process of oxidizing an organic sample with oxygen or air at high temperature

Answer 18

Dry ashing

Question 19

Is the thermochemical decompositions of organic compounds at elevated temperature in the absences of oxygen

Answer 19

Pyrolysis

Question 20

Is the thermochemical decompositions of organic compounds at elevated temperature in the presence of oxygen

Answer 20

Combustion

Question 21

sample is mixed with an alkali metal salt

Answer 21

flux

Question 21

Fused to form a water soluble product

Answer 21

melt

Question 22

A type of fluxes that coverts the cationic constituents of the sample to acid-soluble carbonates or oxides

Answer 22

Sodium carbonate

Question 23

A potent acid flux that is particularly useful in attacking the more intractable metal oxides

Answer 23

Potassium pyrosulfate

Question 24

Use for attacking refractory silicate and alumina minerals

Answer 24

Lithium metaborate