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Buffer solutions for calibrating the pH meter |
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| MIL-A-3850
6.4 The Fischer Scientific Co., No. 3-90,
of succinic acid (which has been purified by
Mekker-type burner has been found satisfac-
recrystallizing twice from distilled water and
tory for use in making the volatile matter de-
dried to constant weight in a desiccator over
termination (see 4.4.4.1.2).
calcium chloride), in distilled water, and dilut-
ing to 1 liter.
6.5 If a pyrometer is not available the tem-
perature of the flame may be checked by
6.7.3 Preparation of the buffer solutions. --
noting if complete fusion of pure potassium
Prepare buffer solutions of the indicated pH
chromate (melting point 9680 C.) takes place
at 250 C. by mixing the stock solutions in the
in the bottom of the crucible. In case of dis-
following proportions:
pute a pyrometer should be used to check the
Stock solution m1.
temperature (see 4.4.4.1.2).
C
B
A
pH of buffer solution
8.22
1.78
---
4.0
6.6 A Beckman pH meter industrial Model
6.32
3.68
---
5.0
M, has been found satisfactory for the deter-
1.23
---
8.77
6.0
3.77
---
6.23
mination of the pH value (see 4.4.7).
7.0
5.35
----
4.65
8.0
8.26
---
1.75
9.0
6.7 Buffer solutions for calibrating the pH
meter.
6.8 Triton 720, Darven No, 1, and Nacconol
have been found satisfactory dispersing
6.7.1 NBS standard solutions. -- Prepare
agents for making the coarse particles deter-
solutions of National Bureau of Standards'
mination (see 4.4.9).
pH standards numbers 185, 1861, 18611, and
187 according to the directions given on their
Notice.--When Government drawings, specifica-
respective certificates.
tion, or other data are used for any purpose other
than in connection with l definitely related Gover-
6.7.2 Stock solutions. --Prepare a 0.05 molar
ment procurement operation, the United States Gov-
e r n m e n t thereby incurs no responsibility nor any
ing stock solutions for use in the preparation
obligation whatsoever; and the fact that the Gover-
of buffer solutions (see 6.7.3).
ment may have formulated, furnished, or in any way
supplied the said drawings, specifications, or other
6.7.2.1 Solution A .--Prepare a 0.1 molar
data is not to be regarded by implication or otherwise
solution of potassium dihydrogen phosphate
as in any manner licensing the holder or any other
person or corporation, or conveying any rights or
by dissolving 13.61 grams of the material,
permission to manufacture, use, or sell any patented
ACS grade, in distilled water, and diluting to
invention that may in any way be related thereto
1 liter.
Custodians:
6.7.2.2 Solution B. --Prepare a 0.05 molar
A r m y -- O r d n a n c e Corps
Navy-Bureau of Ordnance
solution of sodium borate (borax) by dissolv-
ing 19.10 grams of the material, ACS grade,
Other interest:
in distilled water, and diluting to 1 liter.
Navy--S.
6.7.2.3 Solution. C. --Prepare a 0.05 molar
succinic acid solution by dissolving 6.9 grams
6
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