Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Gold Chloride (Tetrachloroauric(III) Acid Trihydrate) 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 Gold Chloride provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), and aqueous solubility. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Insoluble in Ether, Alkalis and Other Metals (as Sulfates).
HAuCl4 • 3H2O
Formula Wt 393.83
CAS No. 16961-25-4
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
yellow to reddish-yellow solid preparation of gold standard solutions; graphite-furnace AAS melting point, 254 °C appreciable (≥10%)
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49.0% Au Maximum Allowable Insoluble in ether . . . . . . . . . . . . . . . . . . . . 0.1% Alkalis and other metals (as sulfates). . . . . . . . 0.2%
TESTS Assay (Gold content by gravimetry). Evaporate the solution from the test for insoluble in ether to dryness or a syrupy residue. Dissolve the residue in 100 mL of dilute hydrochloric acid (1:19), disregarding any undissolved material. Add 10 mL of
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4156 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
sulfurous acid, and digest on a hot plate (~100 °C) until the precipitate is well coagulated. Filter, wash with dilute hydrochloric acid (1:99), and ignite in a tared, preconditioned crucible. Retain the filtrate and washings. The weight of the residue should be not less than 49.0% of the weight of the sample.
Note: Sulfurous acid assay must be ≥6% as SO2. If not, adjust the volume accordingly.
Insoluble in Ether Weigh accurately about 1 g. Add 10 mL of diethyl ether, allow to stand for 10 min with occasional stirring, filter through a tared filtering crucible of fine porosity, wash with small portions of ether, and dry at 105 °C. Retain the filtrate and washings.
Alkalis and Other Metals (as Sulfates) Evaporate the filtrate and washings reserved from the assay in a tared, preconditioned dish to dryness. Ignite the residue cautiously, and finally ignite at 600 ± 25 °C for 15 min.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4156 ACS Reagent Chemicals, Part 4
