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SECTION 11

PRACTICAL LABORATORY

INFORMATION

11.1

COOLING

 

11.3

Table 11.1

Cooling Mixtures

11.3

Table 11.2 Molecular Lowering of the Melting or Freezing Point

11.4

11.2

DRYING AND HUMIDIFICATION

11.5

Table 11.3

Drying Agents

11.5

Table 11.4 Solutions for Maintaining Constant Humidity

11.6

Table 11.5 Concentration of Solutions of H2SO4, NaOH, and CaCl2 Giving

 

 

 

Specified Vapor Pressures and Percent Humidities at 25 C

11.7

Table 11.6 Relative Humidity from Wet and Dry Bulb Thermometer Readings

11.8

Table 11.7 Relative Humidity from Dew Point Readings

11.9

11.3 BOILING POINTS AND HEATING BATHS

11.10

Table 11.8 Organic Solvents Arranged by Boiling Points

11.10

Table 11.9 Molecular Elevation of the Boiling Point

11.13

Table 11.10 Substances Which Can Be Used for Heating Baths

11.15

11.4

SEPARATION METHODS

11.16

Table 11.11

Solvents of Chromatographic Interest

11.16

Table 11.12 Solvents Having the Same Refractive Index and the Same Density

 

 

 

at 25 C

11.18

Table 11.13 McReynolds’ Constants for Stationary Phases in Gas

 

 

 

Chromatography

11.21

11.4.1

McReynolds’ Constants

11.26

Table 11.14 Characteristics of Selected Supercritical Fluids

11.26

11.4.2

Chromatographic Behavior of Solutes

11.27

Table 11.15 Typical Performances in HPLC for Various Conditions

11.31

11.4.3

Ion-Exchange (Normal Pressure, Columnar)

11.32

Table 11.16 Guide to Ion-Exchange Resins

11.33

Table 11.17 Relative Selectivity of Various Counter Cations

11.37

Table 11.18 Relative Selectivity of Various Counter Anions

11.38

11.5

GRAVIMETRIC ANALYSIS

11.41

Table 11.19

Gravimetric Factors

11.41

Table 11.20 Elements Precipitated by General Analytical Reagents

11.67

Table 11.21 Cleaning Solutions for Fritted Glassware

11.69

Table 11.22

Common Fluxes

11.70

Table 11.23

Membrane Filters

11.70

Table 11.24 Porosities of Fritted Glassware

11.71

Table 11.25

Tolerances for Analytical Weights

11.71

Table 11.26 Heating Temperatures, Composition of Weighing Forms, and

 

 

 

Gravimetric Factors

11.72

11.6

VOLUMETRIC ANALYSIS

11.74

11.6.1

Acid-Base Titrations in Aqueous Media

11.74

Table 11.27 Primary Standards for Aqueous Acid-Base Titrations

11.74

Table 11.28

Titrimetric (Volumetric) Factors

11.76

11.6.2 Titrimetric (Volumetric) Factors for Acid-Base Titrations

11.82

11.6.3 Standard Volumetric (Titrimetric) Redox Solutions

11.82

11.6.4

Indicators for Redox Titrations

11.83

Table 11.29 Equations for the Redox Determinations of the Elements with

 

 

 

Equivalent Weights

11.84

11.1

11.2

 

SECTION 11

 

11.6.5

Precipitation Titrations

11.89

11.6.6

Complexometric Titrations

11.89

11.6.7

Masking Agents

11.92

11.6.8

Demasking

11.93

Table 11.30 Standard Solutions for Precipitation Titrations

11.94

Table 11.31 Indicators for Precipitation Titrations

11.95

Table 11.32 Properties and Applications of Selected Metal Ion Indicators

11.96

Table 11.33 Variation of 4 with pH

11.97

Table 11.34 Formation Constants of EDTA Complexes at 25 C, Ionic Strength

 

 

 

Approaching Zero

11.97

Table 11.35 Cumulative Formation Constants of Ammine Complexes at 20 C,

 

 

 

Ionic Strength 0.1

11.97

Table 11.36 Masking Agents for Various Elements

11.98

Table 11.37 Masking Agents for Anions and Neutral Molecules

11.100

Table 11.38 Common Demasking Agents

11.100

Table 11.39 Amino Acids pI and pKa Values

11.102

Table 11.40

Tolerances of Volumetric Flasks

11.102

Table 11.41

Pipet Capacity Tolerances

11.103

Table 11.42

Tolerances of Micropipets (Eppendorf)

11.103

Table 11.43 Buret Accuracy Tolerances

11.103

Table 11.44 Factors for Simplified Computation of Volume

11.104

Table 11.45 Cubical Coefficients of Thermal Expansion

11.105

Table 11.46 General Solubility Rules for Inorganic Compounds

11.105

11.7

LABORATORY SOLUTIONS

11.106

Table 11.47 Concentration of Commonly Used Acids and Bases

11.106

Table 11.48

Standard Stock Solutions

11.107

11.7.1 General Reagents, Indicators, and Special Solutions

11.109

Table 11.49 TLV Concentration Limits for Gases and Vapors

11.121

Table 11.50 Some Common Reactive and Incompatible Chemicals

11.130

Table 11.51 Chemicals Recommended for Refrigerated Storage

11.136

Table 11.52 Chemicals Which Polymerize or Decompose on Extended

 

 

 

Refrigeration

11.136

11.8

SIEVES AND SCREENS

11.137

Table 11.53 U.S. Standard Sieve Series

11.137

11.9

THERMOMETRY

11.137

11.9.1

Temperature and Its Measurement

11.137

Table 11.54 Fixed Points in the ITS-90

11.138

11.10

THERMOCOUPLES

11.138

Table 11.55

Thermoelectric Values in Millivolts at Fixed Points for Various

 

 

 

Thermocouples

11.140

Table 11.56 Type B Thermocouples: Platinum–30% Rhodium Alloy vs.

 

 

 

Platinum–6% Rhodium Alloy

11.142

Table 11.57 Type E Thermocouples: Nickel-Chromium Alloy vs. Copper-Nickel

 

 

 

Alloy

11.143

Table 11.58 Type J Thermocouples: Iron vs. Copper-Nickel Alloy

11.144

Table 11.59 Type K Thermocouples: Nickel-Chromium Alloy vs. Nickel-

 

 

 

Aluminum Alloy

11.145

Table 11.60 Type N Thermocouples: Nickel–14.2% Chromium–1.4% Silicon

 

 

 

Alloy vs. Nickel–4.4% Silicon–0.1% Magnesium Alloy

11.146

Table 11.61 Type R Thermocouples: Platinum–13% Rhodium Alloy vs. Platinum

11.147

Table 11.62 Type S Thermocouples: Platinum–10% Rhodium Alloy vs. Platinum

11.148

Table 11.63 Type T Thermocouples: Copper vs. Copper-Nickel Alloy

11.149

11.11 CORRECTION FOR EMERGENT STEM OF THERMOMETERS

11.150

Table 11.64 Values of K for Stem Correction of Thermometers

11.150

 

PRACTICAL

LABORATORY

INFORMATION

 

 

 

11.3

11.1 COOLING

 

 

 

 

 

 

TABLE 11.1

Cooling Mixtures

 

 

 

 

 

 

The table below gives the lowest temperature that can be obtained from a mixture of the inorganic salt with

 

finely shaved dry ice. With the organic substances, dry ice (

 

78 C) in small lumps can be added to the solvent

 

until a slight excess of dry ice remains or liquid nitrogen (

196 C) can be poured into the solvent until a slush

 

is formed that consists of the solid-liquid mixture at its melting point.

 

 

 

 

 

 

 

 

 

 

 

 

 

Quantity of

 

Quantity of

Temperature,

 

 

Substance

 

substance, g

 

water, mL

C

 

 

 

 

 

 

 

 

 

Ammonium nitrate

100

94

4.0

 

 

Sodium nitrate

 

75

100

5.3

 

 

Sodium thiosulfate 5-water

110

100

8.0

 

 

Sodium chloride

 

36

100

10.0

 

 

Sodium nitrate

 

50

100

17.8

 

 

Sodium bromide

 

66

100

28

 

 

Magnesium chloride

85

100

34

 

 

Calcium chloride 6-water

100

81

40.3

 

 

 

 

100

70

55

 

 

 

 

 

 

 

 

Substance

Temperature,

C

 

Substance

Temperature,

C

 

 

 

 

 

 

 

 

Ethylene glycol

 

13

 

 

Acetone

77

 

1,2-Dichlorobenzene

17

 

 

Ethyl acetate

84

 

Carbon tetrachloride

 

22.9

 

2-Butanone

87

 

Bromobenzene

 

31

 

 

Hexane

95

 

Methoxybenzene

 

37

 

 

Methanol

98

 

Bis(2-ethoxyethyl) ether

44

 

 

Carbon disulfide

112

 

Chlorobenzene

 

45

 

 

Bromoethane

119

 

N -Methylaniline

 

57

 

 

Pentane

130

 

p -Cymene

 

68

 

 

2-Methylbutane

160

 

 

 

 

 

 

 

 

 

11.4

 

 

SECTION

11

 

 

 

TABLE 11.2 Molecular Lowering of the Melting or Freezing Point

 

 

 

 

Cryoscopic constants.

 

 

 

 

 

 

 

 

 

The cryoscopic constant

gives Ktheƒ depression of the melting point

 

 

T (in degrees Celsius) produced when 1

mol of solute is dissolved in 1000 g of a solvent. It is applicable only to dilute solutions for which the number

of moles of solute is negligible in comparison with the number of moles of solvent. It is often used for molecular

 

weight determinations.

 

 

 

 

 

 

 

 

 

 

 

 

M

2

1000

w K2

ƒ

 

 

 

 

 

w

1 T

 

 

 

 

 

 

 

 

 

 

 

 

where

w 1 is the weight of the solvent and

w 2 is the weight of the solute whose molecular weight is

M 2 .

 

 

 

 

 

 

 

 

 

 

 

Compound

K ƒ

 

 

 

 

 

Compound

K ƒ

 

 

 

 

 

 

 

Acetamide

 

4.04

 

 

Diphenylamine

8.60

Acetic acid

 

3.90

 

 

Diphenyl ether

7.88

Acetone

 

2.40

 

 

1,2-Ethanediamine

2.43

Ammonia

 

0.957

 

 

Ethoxybenzene

7.15

Aniline

 

5.87

 

 

 

Formamide

3.85

Antimony(III) chloride

 

17.95

 

Formic acid

2.77

Benzene

 

5.12

 

 

 

Glycerol

3.3 to 3.7

Benzonitrile

 

5.34

 

 

 

Hexamethylphosphoramide

6.93

Benzophenone

 

9.8

 

 

 

 

 

 

 

Bicyclohexane

 

14.52

 

 

 

N -Methylacetamide

6.65

Biphenyl

 

8.0

 

 

 

2-Methyl-2-butanol

10.4

Borneol

 

35.8

 

 

 

Methylcyclohexane

14.13

Bornylamine

 

40.6

 

 

 

Methyl

 

cis -9-octadecenoate

3.4

Butanedinitrile

 

18.26

 

 

 

2-Methyl-2-propanol

8.37

Camphene

 

31.08

Naphthalene

 

 

6.94

Camphoquinone

 

45.7

 

Nitrobenzene

6.852

D -( )-Camphor

 

39.7

 

Octadecanoic acid

4.50

Carbon tetrachloride

 

29.8

 

2-Oxohexamethyleneimine

7.30

o -Cresol

 

5.60

 

 

 

Phenol

 

 

7.40

p -Cresol

 

6.96

 

 

 

Pyridine

4.75

Cyclohexane

 

20.0

 

Quinoline

 

 

1.95

Cyclohexanol

 

39.3

 

Succinonitrile

18.26

Cyclohexylcyclohexane

 

14.52

Sulfuric acid

1.86

Cyclopentadecanone

 

21.3

1,1,2,2-Tetrabromoethane

21.7

cis -Decahydronaphthalene

 

19.47

1,1,2,2-Tetrachloro-

 

trans

-Decahydronaphthalene

20.81

 

1,2-difluoroethane

37.7

Dibenz[ de ,kl ]anthracene

25.7

 

 

 

Tetramethylene sulfone

64.1

Dibenzyl ether

 

6.27

 

 

 

p -Toluidine

5.372

1,2-Dibromoethane

 

12.5

Tribromomethane

14.4

Diethyl ether

 

1.79

 

 

1,3,3-Trimethyl-2-oxabicyclo-

 

1,2-Dimethoxybenzene

 

6.38

 

[2.2.2.]octane

6.7

N,N

-Dimethylacetamide

 

4.46

 

Triphenylmethane

12.45

2,2-Dimethyl-1-propanol

 

11.0

Water

 

 

1.86

Dimethyl sulfoxide

 

4.07

 

 

 

p -Xylene

4.3

1,4-Dioxane

 

4.63

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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