How is #"aqua regia"# prepared?

1 Answer
Dec 23, 2017

Typically you add one part conc. nitric to three parts conc. hydrochloric acid...

Explanation:

Such addition forms the highly oxidizing nitrosyl cation species...

#HNO_3(aq) +3H^(+) +2e^(-)rarr NO^(+)+2H_2O#

As a tip, I often found it works best in a 1:1 ratio of the conc. acids. You really do not want to pfaff too much about with conc. acids....do the dilution by #"GOGGLE-ENCLOSED!!"# eye....

Note that conc. #HCl#, the stuff that you use in a lab, is approx. #10.6*mol*L^-#, whereas conc. #HNO_3# is approx. #15*mol*L^-1#, so the 1:1 dilution is just about reasonable.