PAC Database - Detailed Chemical Data
Chemical Identity
| Chemical | CAS# | UN# | Health Code Numbers | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Aqua regia (75% hydrochloric + 25% nitric acid) | 8007-56-5 | 1798 |
14.01
14.02
11.01
4.01
11.00
4.11
|
|||||||||
| Formula | Synonyms | |||||||||||
| 3H.Cl.H.N.O3 | AQUA REGIA, ACIDE CHLORHYDRIQUE ET ACIDE NITRIQUE EN MÉLANGE (DOT FRENCH, ACIDE NITRIQUE ET ACIDE CHLORHYDRIQUE EN MÉLANGE (DOT FRENCH, ACIDE NITROCHLORHYDRIQUE (DOT FRENCH), ACIDO NITROCLORHÍDRICO (DOT SPANISH), AGUA REGIA (DOT SPANISH), CHLOROAZOTIC ACID, CHLORONITROUS ACID, EAU RÉGALE (DOT FRENCH), MET-ETCH, NITROHYDROCHLORIC ACID, NITROMURIATIC ACID | |||||||||||
Physical Properties
| Mol Wt | State | MP (°C) | BP (°C) | VP (Hg) | VP (°C) | SG | LEL (ppm) |
|---|---|---|---|---|---|---|---|
| 99.47 | L |
PAC Values
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 1.8 | 22 | 100 |
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 7.3 | 90 | 410 |
Technical Basis
Aqua regia is a complex of hydrochloric acid and nitric acid (3:1). A review of available sources identified no acute toxicity data or exposure limits for aqua regia. There are exposure limits for hydrogen chloride (AEGLs; CASRN: 7647-01-0) and nitric acid (AEGLs; CASRN: 7697-37-2). These AEGLs are comparable in magnitude. The AEGLs for hydrogen chloride were selected as the TEELs due to their priority among the emergency exposure limits (Section 1) and because it is the main component of the aqua regia mixture.
• TEEL-1 = AEGL-1 (hydrogen chloride, CASRN: 7647-01-0)
• TEEL-2 = AEGL-2 (hydrogen chloride, CASRN: 7647-01-0)
• TEEL-3 = AEGL-3 (hydrogen chloride, CASRN: 7647-01-0)
This review generated TEEL ppm values consistent with Rev. 29A. The discrepancies in the units mg/m3 values may be due to the use of an incorrect molecular weight (Rev. 29A reported the molecular formula as H3Cl·HNO3, with a molecular weight of 99.47 mg/m3). The current TEELs were developed using a molecular weight of 172.39 mg/m3, which accounts for the correct ratio of the mixture components 3HCl·HNO3.
• TEEL-1 = AEGL-1 (hydrogen chloride, CASRN: 7647-01-0)
• TEEL-2 = AEGL-2 (hydrogen chloride, CASRN: 7647-01-0)
• TEEL-3 = AEGL-3 (hydrogen chloride, CASRN: 7647-01-0)
This review generated TEEL ppm values consistent with Rev. 29A. The discrepancies in the units mg/m3 values may be due to the use of an incorrect molecular weight (Rev. 29A reported the molecular formula as H3Cl·HNO3, with a molecular weight of 99.47 mg/m3). The current TEELs were developed using a molecular weight of 172.39 mg/m3, which accounts for the correct ratio of the mixture components 3HCl·HNO3.
References
Chemical information. Retrieved from: https://pubchem.ncbi.nlm.nih.gov/compound/Aqua-regia
Hydrogen chloride AEGLs retrieved from: https://www.epa.gov/aegl/hydrogen-chloride-results-aegl-program
Nitric acid AEGLs retrieved from: https://www.epa.gov/aegl/nitric-acid-results-aegl-program