Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Formic Acid, 96% Part 4, Monographs for Reagent Chemicals: General Descriptions, Specifications, and Tests eISBN: 9780841230460 Tom Tyner Chair, ACS Committee on Analytical Reagents James Francis Secretary, ACS Committee on Analytical Reagents
ABSTRACT This monograph for Formic Acid, 96% provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), aqueous solubility, density, and pKa. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Color (APHA), Dilution Test, Residue after Evaporation, Acetic Acid, Ammonium, Chloride, Sulfate, Sulfite, Heavy Metals, Iron. Special caution is advised for the handling or testing of this substance.
HCOOH
Formula Wt 46.03
CAS No. 64-18-6
C a u t i o n : Slow decomposition of this reagent may produce pressure in the bottle. Loosen cap occasionally to vent the gas.
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . . Density . . . . . . . . . . . . . . . . pKa . . . . . . . . . . . . . . . . . .
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clear, colorless liquid chemical synthesis boiling point, 100 °C miscible 1.22 3.7
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥96.0% HCOOH Maximum Allowable Color (APHA) . . . . . . . . . . . . . . . . . . . . . . . 15 Dilution test. . . . . . . . . . . . . . . . . . . . . . . . Passes test Residue after evaporation . . . . . . . . . . . . . . . 0.003%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4149 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Acetic acid (CH3COOH) . Ammonium (NH4) . . . . Chloride (Cl) . . . . . . . Sulfate (SO4) . . . . . . . Sulfite (SO3) . . . . . . . . Heavy metals (as Pb) . . Iron (Fe) . . . . . . . . . .
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0.4% 0.005% 0.001% 0.003% Passes test 0.001% 0.001%
TESTS Assay (By acid–base titrimetry). Tare a small glass-stoppered conical flask containing 15 mL of water. Quickly introduce 1.0–1.5 mL of the sample, and weigh. Dilute with water to about 50 mL and titrate with 1 N sodium hydroxide volumetric solution, using 0.15 mL of phenolphthalein indicator. One milliliter of 1 N sodium hydroxide corresponds to 0.04603 g of HCOOH.
Color (APHA) [Part 2: Measurement of Physical Properties; Color (APHA); Procedure for Color (APHA)].
Dilution Test Dilute 1 volume of the acid with 3 volumes of water. No turbidity should be observed within 1 h.
Residue after Evaporation [Part 2: Gravimetric Methods; Residue after Evaporation]. Evaporate 50.0 g (42 mL) to dryness in a tared, preconditioned dish on a hot plate (~100 °C), and dry the residue at 105 °C for 30 min.
Acetic Acid Analyze the sample by gas chromatography as described in [Part 2: Chromatography; Recommended Procedures; Gas Chromatography]. The following specific conditions are satisfactory. Column . . . . . . . . . . . . . . . . . . . Column Temperature . . . . . . . . . . Injection Port Temperature . . . . . . Detector Temperature . . . . . . . . . Detector Current. . . . . . . . . . . . . Carrier Gas . . . . . . . . . . . . . . . . Sample Size . . . . . . . . . . . . . . . . Detector . . . . . . . . . . . . . . . . . . Approximate Retention Times (min).
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. 1.8 m × 6.4 mm, stainless steel, packed with 80/100 mesh Porapak Q . 150 °C . 150 °C . 175 °C . 200 mA . Helium at 40 mL/min . 5 µL . Thermal conductivity . Water, 1.2; formic acid, 3.5; acetic acid, 8.1
Measure the area under all peaks, and calculate the acetic acid content in area percent.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4149 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Ammonium Add 2.0 g (1.6 mL) of sample to 25 mL of water, and cautiously add 20 mL of freshly boiled 10% sodium hydroxide solution while cooling the solution. Transfer to a 50 mL Nessler tube, add 2 mL of Nessler reagent, and dilute to volume with water. The color produced should not exceed that produced by 0.01 mg of ammonium ion treated identically.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 1.0 g (0.83 mL) sample.
Sulfate [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 3]. Use 1.7 g (1.4 mL) sample.
Sulfite Dilute 25 mL with 25 mL of water; add 0.10 mL of 0.1 N iodine solution. The mixture should retain a distinct yellow color.
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. To 2 g (1.6 mL) in a beaker, add 1.0 mL of 1% sodium carbonate reagent solution, and evaporate to dryness. Dissolve the residue in about 20 mL of water, and dilute with water to 25 mL.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. To 6.0 g (5.0 mL) in a beaker, add 1.0 mL of 1% sodium carbonate reagent solution, and evaporate to dryness. Dissolve the residue in 6 mL of hydrochloric acid, dilute with water to 60 mL, and use 10 mL of this solution without further acidification.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4149 ACS Reagent Chemicals, Part 4
