Orange to yellow color change of a chloroauric acid solution

[MicheleM]

Dear members, good morning.
I recently observed a color change ( from orange to deep yellow) of a chloroauric acid solution and i do not have a conclusive explanation, It is just for curiosity but:
1) after a first gold drop (from a yellow-green solution ) that looked good with a nice brown powder, i decided to refine it with acid and bleach.

2) the dissolved powder gave a beautiful orange solution, apparently signalling a high purity gold bearing solution.

3) i put the beaker on low heat for about 48 h to remove any possible bleach residue (i didn't overuse it too much) and to evaporate part of the H20 .

4) in the end the solution changed color from orange to deep yellow (orange oriented but definitely yellow)
Now, i did some research but i didn't find any straightforward explanation.
I think that the only H20 evaporation should make solutions more orange , not yellow, so the applied heat probably destroyed some ionic species linked to the chloroauric acid that give the orange color.
Do you have any explanation?
Thanks! Have a good day

 

[Lino1406]

Gold chloride is red, chloroauric acid is yellow. Red+yellow=orange

 

[MicheleM]

Thank you @Lino1406 for the reply,
gold chloride+ chloroauric acid in aqueous solution
Au_{2}Cl_{6} + H_{2}0 + H[AuCl_{4}]*n* H_{2}O+... Should give orange , then heating up.. less water and more yellowish color, i have to think more about it. Thank you again

 

[Lino1406]

Thank you @Lino1406 for the reply,
gold chloride+ chloroauric acid in aqueous solution
Au_{2}Cl_{6} + H_{2}0 + H[AuCl_{4}]*n* H_{2}O+... Should give orange , then heating up.. less water and more yellowish color, i have to think more about it. Thank you again

Au2Cl6 + 2HCl = 2HAuCl4

 

[MicheleM]

I forgot the HCl! , Now i got it