ASTM E224 Analysis of Hydrochloric Acid

Scope:

ASTM E224 standard method covers the procedures for the analysis of hydrochloric acid. The analytical procedures included in this standard are as follows:

Parameters	Sections
Total Acidity	8 to 16
Baumé Gravity	17 to 26
Sulfated Ash	27 to 34
Iron	35 to 44
Colour	45 to 52
Total Sulfur	53 to 59

Test procedure:

The following procedures are described in ASTM E224: 

Total acidity determination: A weighed sample of the acid is diluted in water and titrated with standardized 0.5 meq/mL (N) sodium hydroxide solution, using phenolphthalein as the indicator.

Baumé gravity determination: A sample of hydrochloric acid is placed in a hydrometer cylinder and when the temperature is constant, the Baumé gravity is read from the glass hydrometer. The Baumé gravity is used to classify various grades of hydrochloric acid.

Sulfated ash content determination: A weighed sample of acid, to which sulfuric acid has been added, is evaporated, ignited, and the residue is weighed.

Iron content determination: The iron is reduced and determined calorimetrically with 1,10-phenanthroline (ortho-phenanthroline), which forms an orange-red complex with ferrous iron. The intensity of the color is measured in a photometer calibrated against standardized solutions.

Color determination: An arbitrary color scale is used that is based on the color produced by adding known amounts of ferric iron to the hydrochloric acid.

Total sulfur content determination: A sample of acid is treated with bromine to oxidize any oxidizable sulfur compounds to sulfate. The sulfate is precipitated and weighed as barium sulfate.

Video 01: Titration of HCl with NaOH

Specimen size:

The size of the sample used for ASTM E224 testing shall be sufficient to perform all analyses without the reuse of any portion of the sample

Data:

The calculations for the analytical procedures described in ASTM E224 are as follows,

V= corrected mL of NaOH solution required for titration of the sample, N= normality of NaOH solution, W= sample used

The Platinum-Cobalt color scale has wide-spread use to determine the color of HCl.

M= iron found from the calibration curve

R= weight of evaporating dish and residue, D= weight of the evaporating dish, W= sample used

A= BaSO4 precipitate, W= sample used

Conclusion:

ASTM E224 standard method covers the procedures for the analysis of hydrochloric acid.