[Wienerbroed]

I need to write the balanced reaction between aqua regia (HNO₃ + 3HCl) with gold (Au), with the gold oxidizing to 3+ ions.

Based on what I've read online the reaction should go like:

4HNO₃ + 12HCl + 3Au ---> 4NO + 8H₂O + 3AuCl₄^-

If this is true, how come 3AuCl₄^- is formed instead of 3AuCl₃, considering Au has oxidation number 3+ in this case?

[sjb]

Your equation is not balanced - check the charges.

Perhaps have a look at https://en.wikipedia.org/wiki/Aqua_regia#Dissolving_gold or similar?