Aqua regia is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of 1:3. Aqua regia is a yellow-orange fuming liquid. Aqua regia was so named because it can dissolve the noble metals gold and platinum.
Formula: HNO3+3 HCl
Vapor pressure: 2.1 kPa
Boiling point: 108 °C
Melting point: -42 °C
Density: 1.21 g/cm³
