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PRACTICAL |
LABORATORY INFORMATION |
11.71 |
TABLE 11.24 |
Porosities of Fritted Glassware |
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Nominal maximum |
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Porosity |
pore size, m |
Principal uses |
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Extra coarse |
170– 220 |
Filtration of very coarse materials. Gas dispersion, gas washing, |
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and extractor beds. Support of other filter materials. |
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Coarse |
40– 60 |
Filtration of coarse materials. Gas dispersion, gas washing, gas ab- |
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sorption. Mercury filtration. For extraction apparatus. |
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Medium |
10– 15 |
Filtration of crystalline precipitates. Removal of “floaters” from |
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distilled water. |
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Fine |
4– 5.5 |
Filtration of fine precipitates. As a mercury valve. In extraction |
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apparatus. |
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Very fine |
2– 2.5 |
General bacteria filtrations. |
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Ultra fine |
0.9– 1.4 |
General bacteria filtrations. |
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TABLE 11.25 Tolerances for Analytical Weights
By Alan D. Westland with Fred E. Beamish.
This table gives the individual and group tolerances established by the National Bureau of Standards (Washing-
ton, D.C.) for classes M, S, S-1, and P weights. Individual tolerances are “acceptance tolerances” for new weights. Group tolerances are defined by the National Bureau of Standards as follows: “The corrections of individual weights shall be such that no combination of weights that is intended to be used in a weighing shall differ from the sum of the nominal values by more than the amount listed under the group tolerances.”
For class S-1 weights, two-thirds of the weights in a set must be within one-half of the individual tolerances given below. No group tolerances have been specified for class P weights. See Natl. Bur. Standards Circ. 547, sec. 1 (1954).
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Class M |
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Class S |
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Class S-1, |
Class P, |
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Individual |
Group |
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Individual |
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Group |
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individual |
individual |
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tolerance, |
tolerance, |
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tolerance, |
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tolerance, |
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tolerance, |
tolerance, |
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Denomination |
mg |
mg |
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mg |
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mg |
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mg |
mg |
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100 g |
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0.50 |
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0.25 |
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None |
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1.0 |
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2.0 |
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50 g |
0.25 |
None |
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0.12 |
specified |
0.60 |
1.2 |
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30 g |
0.15 |
specified |
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0.074 |
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0.45 |
0.90 |
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20 |
g |
0.10 |
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0.074 |
0.154 |
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0.35 |
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0.70 |
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10 |
g |
0.050 |
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0.074 |
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0.25 |
0.50 |
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5 |
g |
0.034 |
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0.054 |
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0.18 |
0.36 |
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3 |
g |
0.034 |
0.065 |
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0.054 |
0.105 |
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0.15 |
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0.14 |
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2 |
g |
0.034 |
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0.054 |
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0.13 |
0.26 |
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1 |
g |
0.034 |
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0.054 |
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0.10 |
0.20 |
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500 |
mg |
0.0054 |
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0.025 |
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0.080 |
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0.16 |
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300 |
mg |
0.0054 |
0.0105 |
0.025 |
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0.055 |
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0.070 |
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0.14 |
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200 |
mg |
0.0054 |
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0.025 |
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0.060 |
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0.12 |
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100 |
mg |
0.0054 |
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0.025 |
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0.050 |
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0.10 |
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50 |
mg |
0.0054 |
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0.014 |
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0.042 |
0.085 |
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30 |
mg |
0.0054 |
0.0105 |
0.014 |
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0.034 |
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0.038 |
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0.076 |
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20 |
mg |
0.0054 |
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0.014 |
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0.035 |
0.070 |
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11.72 |
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SECTION |
11 |
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TABLE 11.25 |
Tolerances for Analytical Weights ( |
Continued |
) |
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Class M |
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Class S |
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Class S-1, |
Class P, |
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Individual |
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Group |
Individual |
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Group |
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individual |
individual |
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tolerance, |
tolerance, |
tolerance, |
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tolerance, |
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tolerance, |
tolerance, |
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Denomination |
mg |
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mg |
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mg |
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mg |
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mg |
mg |
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10 |
mg |
0.0054 |
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0.014 |
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0.030 |
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0.060 |
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5 |
mg |
0.0054 |
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0.014 |
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0.028 |
0.055 |
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3 |
mg |
0.0054 |
0.0105 |
0.014 |
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0.034 |
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0.026 |
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0.052 |
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2 |
mg |
0.0054 |
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0.014 |
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0.025 |
0.050 |
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1 |
mg |
0.0054 |
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0.014 |
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0.025 |
0.050 |
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1 ⁄2 |
mg |
0.0054 |
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0.014 |
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0.025 |
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. . . . . . . . . . . |
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TABLE 11.26 Heating Temperatures, Composition of Weighing Forms, and Gravimetric Factors
The minimum temperature required for heating a pure precipitate to constant weight is frequently lower than that commonly recommended in gravimetric procedures. However, the higher temperature is very often still to be preferred in order to ensure that contaminating substances are expelled. The thermal stability ranges of various precipitates as deduced from thermograms are also tabulated. Where a stronger ignition is advisable, the safe upper limit can be ascertained.
Gravimetric factors are based on the 1993 International Atomic Weights. The factor Ag: 0.7526 given in the
first line of the table indicates that the weight of precipitate obtained (AgCl) is to be multiplied by 0.7526 to calculate the corresponding weight of silver.
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Thermal stability |
Final heating |
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Composition of |
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Element |
range, C |
temperature, C |
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weighing form |
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Gravimetric factors |
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Ag |
70– 600 |
130– 150 |
AgCl |
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Ag: 0.7526 |
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Al |
475 |
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1200 |
Al |
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2 O 3 |
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Al: 0.5293 |
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743 |
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743 |
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AlPO |
4 |
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Al: 0.2212; Al |
2 O |
3 |
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: 0.4180 |
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102– 220 |
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110 |
Al(C |
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9 H |
6 NO) |
3 |
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Al: 0.0587; Al |
2 O |
3 |
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: 0.1110 |
As |
200– 275 |
105– 110 |
Al |
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2 S 3 |
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As: 0.6090; As |
2 O |
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3 |
: 0.8041 |
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850 |
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Mg |
2 As |
2 O 7 |
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As: 0.4827; As |
2 O |
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3 |
: 0.6373 |
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vacuum at 25 |
MgNH |
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4 AsO |
4 |
· 6H |
2 O |
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As: 0.2589 |
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Au |
20– 957 |
1060 |
Au |
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Ba |
780– 1100 |
780 |
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BaSO |
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4 |
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Ba: 0.5884; BaO: 0.6570 |
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60 |
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60 |
BaCrO |
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4 |
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Ba: 0.5421; BaO: 0.6053 |
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Be |
900 |
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1000 |
BeO |
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Be: 0.3603 |
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Bi |
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100 |
BiOCl |
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Bi: 0.8024; Bi |
2 O |
3 |
: 0.8946 |
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100 |
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Bi(C |
12 |
H 10 NOS) |
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3 |
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Bi: 0.2387 |
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379– 961 |
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800 |
BiPO |
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4 |
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Bi: 0.6875; Bi |
2 O |
3 |
: 0.7665 |
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Br |
70– 946 |
130– 150 |
AgBr |
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Br: 0.4256 |
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Ca |
478– 635 |
475– 525 |
CaCO |
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3 |
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Ca: 0.4004; CaO: 0.5601 |
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838– 1025 |
950– 1000 |
CaO |
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Ca: 0.7147 |
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air-dried |
Ca(picrolonate) |
2 |
· 8H |
2 O |
Ca: 0.05642 |
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Cd |
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320 |
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CdSO |
4 |
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Cd: 0.5392; CdO: 0.6159 |
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125 |
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Cd(C |
10 |
H 6 NO |
2 )2 |
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Cd: 0.2462 |
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218– 420 |
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CdS |
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Cd: 0.7781; CdO: 0.8888 |
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Ce |
360 |
500– 600 |
CeO |
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2 |
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Ce: 0.8141 |
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Cl |
70– 600 |
130– 150 |
AgCl |
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Cl: 0.2474 |
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PRACTICAL LABORATORY INFORMATION |
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11.73 |
TABLE 11.26 |
Heating Temperatures, Composition of Weighing Forms, and Gravimetric Factors ( |
Continued |
) |
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Thermal stability |
Final heating |
Composition of |
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Element |
range, C |
temperature, C |
weighing form |
Gravimetric factors |
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Co
Cr
Cu
F
Fe
Ga
Hg
I
In
Ir
K
Li
Mg
Mn
Mo
N (as NO ) 3
Na
Nb
Ni
Os
P
Pb
Pd
Rb
Re
S
Sb
SCN |
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Se |
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Si |
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285– 946 |
750– 850 |
Co |
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3 O |
4 |
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Co: 0.7342 |
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130 |
Co(C |
|
10 |
H |
6 NO |
2 )3 |
· 2H |
2 O |
Co: 0.09639; CoO: 0.1226 |
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450– 500 |
CoSO |
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4 |
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Co: 0.3802 |
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120 |
PbCrO |
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4 |
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Cr: 0.1609 |
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105– 120 |
CuSCN |
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Cu: 0.5225; CuO: 0.6540 |
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115 |
100– 105 |
Cu(C |
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7 H |
5 NO |
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2 )2 |
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Cu: 0.1891 |
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105– 115 |
Cu(C |
|
13 |
H |
11 |
NO |
2 ) |
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Cu: 0.2201 |
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110– 115 |
Cu(C |
|
10 |
H |
6 NO |
2 ) · H 2 O |
|
Cu: 0.1494 |
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105 |
Cu(C |
|
12 |
H |
10 |
NOS) |
2 |
· H 2 O |
Cu: 0.1237 |
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66– 538 |
130– 140 |
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PbClF |
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F: 0.07261 |
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470– 946 |
900 |
Fe |
|
2 O |
3 |
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Fe: 0.6994 |
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408– 946 |
900 |
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Ga |
|
2 O |
3 |
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Ga: 0.7439 |
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105 |
Hg(C |
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12 |
H |
10 |
NOS) |
2 |
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Hg: 0.3169 |
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60– 900 |
130– 150 |
AgI |
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I: 0.5405 |
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345– 1200 |
1200 |
|
In |
|
2 O 3 |
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In: 0.8271 |
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IrO |
2 |
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Ir: 0.8573 |
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73– 653 |
|
653 |
KClO |
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4 |
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K: 0.2822; K |
2 O: 0.3399 |
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270 |
K |
2 PtCl |
6 |
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K: 0.1609; K |
2 O: 0.1938 |
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KIO |
4 |
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K: 0.1700 |
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120 |
KB(C |
|
6 H |
5 )4 |
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K: 0.1091 |
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|
200 |
Li |
|
2 SO |
4 |
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Li: 0.1263; Li |
2 O: 0.2718 |
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|
1050– 1100 |
|
Mg |
|
2 P 2 O |
7 |
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Mg: 0.2184; MgO: 0.3622 |
|||||
88– 300 |
155– 160 |
Mg(C |
|
|
9 H |
6 NO) |
2 |
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Mg: 0.07775; MgO: 0.1289 |
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946 |
1000 |
Mn |
|
3 O |
4 |
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Mn: 0.7203 |
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|
1000 |
Mn |
|
2 P 2 O |
7 |
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|
Mn: 0.3871; MnO: 0.4998 |
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|
|
505 |
PbMoO |
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|
4 |
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Mo: 0.2613; MoO |
3 : 0.3291 |
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|
500– 525 |
MoO |
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3 |
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Mo: 0.6666 |
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20– 242 |
|
105 |
Nitron nitrate |
|
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|
|
N: 0.3732; NO |
|
3 : 0.1652 |
|||||||
360– 674 |
125 |
|
NaMg(UO |
|
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|
|
2 )3 (C |
2 H |
3 O |
2 )9 · |
Na: 0.01527; Na |
|
2 O: |
||
650– 950 |
900 |
|
Nb |
|
6.5 |
H |
|
2 O |
|
|
|
|
|
0.02058 |
|
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|
2 O |
3 |
|
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|
Nb: 0.6990 |
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|
||||
79– 172 |
110– 120 |
|
Ni(C |
|
|
4 H |
7 N |
2 O |
2 )2 |
|
|
|
Ni: 0.2032; NiO: 0.2586 |
||||
|
800 (in H |
2 ) |
Os metal |
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|
|
477 |
Mg |
|
2 P 2 O |
7 |
|
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|
|
|
P: 0.2783; PO |
4 |
: 0.8536 |
|||
160– 415 |
110 |
(NH |
|
4 )3 [P(Mo |
3 O |
10 |
)4 ] |
P: 0.0165; P |
2 O |
5 : 0.0378 |
|||||||
271– 959 |
500– 600 |
PbSO |
|
|
4 |
|
|
|
|
|
|
|
Pb: 0.6832; PbO: 0.7359 |
||||
|
|
600 |
PbMoO |
|
|
|
4 |
|
|
|
|
|
Pb: 0.5643; PbO: 0.6078 |
||||
|
|
120 |
PbCrO |
|
|
4 |
|
|
|
|
|
|
Pb: 0.6411 |
|
|
||
271– 959 |
600– 800 |
|
PbSO |
|
|
4 |
|
|
|
|
|
|
|
Pb: 0.6832; PbO: 0.7359 |
|||
|
|
105 |
Pb(C |
|
12 |
H |
10 |
NOS) |
2 |
|
|
Pb: 0.3240 |
|
|
|||
45– 171 |
110 |
Pd(C |
|
|
4 H |
7 N |
2 O |
2 )2 |
|
|
|
Pd: 0.3162 |
|
|
|||
70– 674 |
|
674 |
Rb |
|
2 PtCl |
6 |
|
|
|
|
|
Rb: 0.2954; Rb |
|
2 O: 0.3230 |
|||
|
|
130 |
(C |
|
6 H |
5 )4 AsReO |
4 |
|
|
|
Re: 0.2939 |
|
|
||||
|
|
110 |
Nitron perrhenate |
|
|
Re: 0.3306 |
|
|
|
||||||||
|
|
780 |
BaSO |
|
4 |
|
|
|
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|
|
S: 0.1374; SO |
3 |
: 0.3430; |
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|
SO |
4 : 0.4116 |
|
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|
100 |
Sb(C |
|
|
12 |
H |
10 |
NOS) |
3 |
|
|
Sb: 0.1581 |
|
|
||
|
|
130 |
AgSCN |
|
|
|
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|
|
|
|
SCN: 0.3500 |
|
|
|
||
|
110– 120 |
CuSCN |
|
|
|
|
|
|
|
|
SCN: 0.4775 |
|
|
|
|||
|
120– 130 |
Se metal |
|
|
|
|
|
|
|
SeO |
2 |
: 1.4052 |
|
|
|||
358– 946 |
|
358 |
SiO |
2 |
|
|
|
|
|
|
|
|
Si: 0.4675 |
|
|
||