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Due to the reaction between its components resulting in its decomposition, aqua regia quickly loses its effectiveness (yet remains a strong acid), so its components are usually only mixed immediately before use.

 

Upon mixing of concentrated hydrochloric acid and concentrated nitric acid, chemical reactions occur. These reactions result in the volatile products nitrosyl chloride and chlorine as evidenced by the fuming nature and characteristic yellow color of aqua regia. As the volatile products escape from solution, the aqua regia loses its potency.

 

$$\ce{HNO3 + 3HCl -> NOCl + Cl2 + 2H2O}$$

Due to the reaction between its components resulting in its decomposition, aqua regia quickly loses its effectiveness (yet remains a strong acid), so its components are usually only mixed immediately before use.

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Upon mixing of concentrated hydrochloric acid and concentrated nitric acid, chemical reactions occur. These reactions result in the volatile products nitrosyl chloride and chlorine as evidenced by the fuming nature and characteristic yellow color of aqua regia. As the volatile products escape from solution, the aqua regia loses its potency.

$$\ce{HNO3 + 3HCl -> NOCl + Cl2 + 2H2O}$$

No one stores aqua regia for extended periods, because it decomposes rapidly, yielding volatile products that escape from the solution resulting in a loss of potency.

_{Not related to the question but; for those of you interested in reading up on how aqua regia "dissolves" gold have a look at this. And for those of you who want to know a way to easily recover the said gold, have a look at this Nurdrage video}

No one stores aqua regia for extended periods of time, because it decomposes rapidly, yielding volatile products that escape from the solution resulting in a loss of potency.

_{You can also read up on how aqua regia "dissolves" gold here. And for those of you who want to know a way to easily recover the said gold, have a look at this Nurdrage video}

Aqua regia: Why does it dissolves gold but not glass?

Aqua regia: Why does it dissolve gold but not glass?