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PRACTICAL LABORATORY INFORMATION

 

11.103

TABLE 11.41 Pipet Capacity Tolerances

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Volumetric transfer pipets

 

 

 

Measuring and serological pipets

 

 

 

 

 

 

 

 

 

 

 

 

Tolerances,*

mL

 

Tolerances,† mL

 

 

 

 

 

 

 

 

 

Class A

Class B

Capacity, mL

 

 

 

Capacity, mL

 

Class B

 

 

 

 

 

0.5

0.006

0.012

0.1

0.005

1

0.006

0.012

0.2

0.008

2

0.006

0.012

0.25

0.008

3

0.01

0.02

0.5

0.01

 

4

0.01

0.02

0.6

0.01

 

5

0.01

0.02

1

0.02

 

10

0.02

0.04

2

0.02

 

15

0.03

0.06

5

0.04

 

20

0.03

0.06

10

0.06

 

25

0.03

0.06

25

0.10

 

50

0.05

0.10

 

 

 

 

100

0.08

0.16

 

 

 

 

* Accuracy tolerances for volumetric transfer pipets are given by ASTM standard E969 and Federal Specification NNN-P- 395.

† Accuracy tolerances for measuring pipets are given by Federal Specification NNN-P-350 and for serological pipets by Federal Specification NNN-P-375.

TABLE 11.42

Tolerances of Micropipets (Eppendorf)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Capacity, L

Accuracy, %

Precision, %

Capacity,

L

Accuracy, %

Precision, %

 

 

 

 

 

 

 

 

 

 

10

1.2

 

0.4

100

0.5

0.2

40

0.6

 

0.2

250

 

0.5

0.15

50

0.5

 

0.2

500

 

0.5

0.15

60

0.5

 

0.2

600

 

0.5

0.15

70

0.5

 

0.2

900

 

0.5

0.15

80

0.5

 

0.2

1000

 

0.5

0.15

 

 

 

 

 

 

 

 

 

TABLE 11.43 Buret Accuracy Tolerances

 

 

 

Accuracy,

mL

 

 

 

 

 

 

 

 

 

Class A* and

Class B and

Capacity, mL

Subdivision, mL

precision grade

standard grade

 

 

 

 

10

0.05

0.02

0.04

25

0.10

0.03

0.06

50

0.10

0.05

0.10

100

0.20

0.10

0.20

* Class A conforms to specifications in ASTM E694 for standard taper stopcocks and to ASTM E287 for Teflon or polytetrafluoroethylene stopcock plugs. The 10-mL size meets the requirements for ASTM D664.

11.104

 

 

 

SECTION 11

 

 

 

 

 

 

TABLE 11.44

 

Factors for Simplified Computation of Volume

 

 

 

 

 

 

The volume is determined by weighing the water, having a temperature of

 

 

t C, contained or delivered by the

apparatus at the same temperature. The weight of water,

w grams, is obtained with brass weights in air having

 

 

a density of 1.20 mg/mL.

 

 

 

 

 

 

 

 

 

For apparatus made of soft glass, the volume contained or delivered at 20

 

C is given by

 

 

 

 

 

 

 

 

20 w

ƒ20 mL

 

 

 

 

 

where

20 is the volume at 20

and ƒ

20 is the factor (apparent specific volume) obtained from the table below for

 

 

 

the temperature

t

at which the

calibration is performed. The volume at any other temperature

 

t may

then be

obtained from

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

20[1 0.00002(t 20)] mL

 

 

 

 

 

 

For apparatus made of any other material, the volume contained or delivered at the temperature

 

 

t

is

 

 

 

 

 

t wf

t mL

 

 

 

 

 

where

w is again the weight in air obtained with brass weights (in grams), and

 

ft is the factor given in the third

column of the table for the temperature

t. The volume at any temperature

t may then be obtained from

 

 

 

 

 

 

 

 

t t[1 (t t)] mL

 

 

 

 

 

where is the cubical coefficient of thermal expansion of the material from which the apparatus is made.

 

 

 

Approximate values of

for some frequently encountered materials are given in Table 11.45.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

t, C

 

 

ƒ 20

 

ƒt

t, C

 

ƒ 20

 

ƒt

 

0

 

1.001 62

1.001 22

20

 

1.002 86

 

1.002 86

1

 

 

54

 

16

21

 

1.003 05

 

1.003 07

2

 

 

48

 

12

22

 

26

 

30

 

3

 

 

43

 

09

23

 

47

 

53

 

4

 

 

41

 

09

24

 

69

 

77

 

5

 

 

1.001 39

1.001 09

25

 

1.003 93

 

1.004 0

6

 

 

40

 

12

26

 

1.004 17

 

29

 

7

 

 

42

 

16

27

 

42

 

56

 

8

 

 

45

 

21

28

 

68

 

84

 

9

 

 

50

28

29

 

95

 

1.005 13

10

 

1.001 56

1.001 36

30

 

1.005 23

 

1.005 43

11

 

 

63

 

45

31

 

1.005 52

1.005 74

12

 

 

72

 

56

32

 

1.005 82

1.006 06

13

 

 

82

 

68

33

 

1.006 13

1.006 39

 

14

 

 

93

 

81

34

 

1.006 44

1.006 72

 

15

 

 

1.002 06

1.001 96

35

 

1.006 77

 

1.007 0

16

 

 

20

 

1.002 12

36

 

1.007 10

 

1.007 42

17

 

 

35

 

29

37

 

1.007 44

 

1.007 78

18

 

 

51

 

47

38

 

1.007 79

 

1.008 15

19

 

 

68

 

66

39

 

1.008 15

 

1.008 53

 

 

 

 

 

 

40

 

1.008 52

 

1.008 91

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PRACTICAL

LABORATORY INFORMATION

 

 

 

 

 

 

11.105

TABLE 11.45

Cubical Coefficients of Thermal Expansion

 

 

 

 

 

 

 

 

This table lists values of , the cubical coefficient of thermal expansion, taken from “Essentials of Quantitative

 

 

Analysis,” by Benedetti-Pichler, and from various other sources. The value of

 

represents the relative increases

 

in volume for a change in temperature of 1

 

 

C at temperatures in the vicinity of 25

 

C, and is equal to 3

, where

is the linear coefficient of thermal expansion. Data are given for the types of glass from which volumetic

 

 

 

apparatus is most commonly made, and also for some other materials which have been or may be used in the

 

 

 

 

fabrication of apparatus employed in analytical work.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Material

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Glasses

 

 

 

 

 

 

 

 

 

 

 

 

 

Alkali-resistant, Corning 728

 

1.90

 

 

5

 

 

 

 

 

 

10

 

 

 

 

 

Gerateglas, Schott G20

 

1.47

 

 

 

 

 

 

 

 

Kimble KG-33 (borosilicate)

 

0.96

 

 

 

 

 

 

 

 

 

N-51A (“Resistant”)

 

1.47

 

 

 

 

 

 

 

 

 

R-6 (soft)

 

2.79

 

 

 

 

 

 

 

Pyrex, Corning 744

 

 

0.96

 

 

 

 

 

 

 

 

Vitreous silica

 

 

0.15

 

 

 

 

 

 

 

Vycor, Corning 790

 

0.24

 

 

 

 

 

 

 

Metals

 

 

 

 

 

 

 

 

 

 

 

 

 

Brass

 

 

 

 

ca.

5.5

 

 

 

 

 

 

 

Copper

 

 

 

 

5.0

 

 

 

 

 

 

 

Gold

 

 

 

 

4.3

 

 

 

 

 

 

 

Monel metal

 

 

 

 

4.0

 

 

 

 

 

 

 

 

Platinum

 

 

 

 

2.7

 

 

 

 

 

 

 

Silver

 

 

 

 

5.7

 

 

 

 

 

 

 

Stainless steel

 

 

ca.

5.3

 

 

 

 

 

 

 

Tantalum

 

 

 

 

ca.

2.0

 

 

 

 

 

 

 

Tungsten

 

 

 

 

1.3

 

 

 

 

 

 

 

 

Plastics and other materials

 

 

 

 

 

 

 

 

 

 

Hard rubber

 

 

 

24

5

 

 

 

 

 

 

 

 

 

10

 

 

 

 

 

 

 

Polyethylene

 

 

 

45– 90

 

 

 

 

 

 

 

 

Polystyrene

 

 

 

 

18– 24

 

 

 

 

 

 

 

 

Porcelain

 

 

 

 

ca.

1.2

 

 

 

 

 

 

 

Teflon (polytetrafluoroethylene)

 

16.5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TABLE 11.46

General Solubility Rules for Inorganic Compounds

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Nitrates

 

All nitrates are soluble.

 

 

 

 

 

 

 

 

Acetates

 

All acetates are soluble; silver acetate is moderately soluble.

 

 

 

 

Chlorides

 

All chlorides are soluble except AgCl, PbCl

2 , and Hg

2 Cl 2 . PbCl 2 is soluble in

 

 

hot water, slightly soluble in cold water.

 

 

 

 

 

 

Sulfates

 

All sulfates are soluble except barium and lead. Silver, mercury(I), and cal-

 

 

 

 

cium are only slightly soluble.

 

 

 

 

 

 

 

Hydrogen sulfates

 

The hydrogen sulfates are more soluble than the sulfates.

 

 

 

 

 

 

Carbonates, phosphates,

All carbonates, phosphates, chromates, and silicates are insoluble, except those

 

 

chromates, silicates

of sodium, potassium, and ammonium. An exception is MgCrO

 

 

4

which is

 

 

 

soluble.

 

 

 

 

 

 

 

 

Hydroxides

 

All hydroxides (except lithium, sodium, potassium, cesium, rubidium, and am-

 

 

 

 

 

monia) are insoluble; Ba(OH)

 

2 is moderately soluble; Ca(OH)

2 and Sr(OH)

2

 

 

are slightly soluble.

 

 

 

 

 

 

 

 

Sulfides

 

All sulfides (except alkali metals, ammonium, magnesium, calcium, and bar-

 

 

 

 

 

ium) are insoluble. Aluminum and chromium sulfides are hydrolyzed and

 

 

 

 

 

precipitate as hydroxides.

 

 

 

 

 

 

 

 

Sodium, potassium,

 

All sodium, potassium, and ammonium salts are soluble. Exceptions:

 

 

 

ammonium

 

Na

4 Sb2 O

7 , K2 NaCo(NO

2 )6 , K2 PtCl 6 , (NH 4 ) 2 PtCl

6

, and (NH

4 )2 NaCo(NO

2 )6 .

Silver

 

All silver salts are insoluble. Exceptions: AgNO

3

and AgClO

4 ; AgC

2 H 3 O 2

and

 

 

Ag

2 SO

4

are moderately soluble.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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