Green solution

[Harold_V]

A couple things are troubling me here.
If gold chloride has a green coloration, it's generally caused by a contaminant, often copper. What ever it is should still remain in solution after the gold has been precipitated, and the solution should reflect the color of the contaminant. The solution appears to be nearly colorless. Why is that?

In the picture where the washed gold is shown, there's a beaker in the background that appears to contain gold chloride. Is that the solution from washing? If so, has it been tested for values? If you've not accounted for all the gold you expected, that could certainly be where some of it has gone.

Harold

 

[butcher]

It just amazes me how sharp Harold is, and how lucky we all are he spends so much of his time as mentor, and watchdog for all of us members.

Good question where did the green go.

 

[rich_2137]

Hi Harold I thought I had mentioned it but the picture is from the second drop using HCl/CL, after I precipitated the gold from the AR solution it turned from the dark green to a light blue/green colour which I tested with stannous (negative)
then the gold powder was washed and re-dissolved in HCL/CL and after i precipitated the second time is when I was left with the clear solution, hope this makes a little more sence

Rich

 

[Harold_V]

Hi Harold I thought I had mentioned it but the picture is from the second drop using HCl/CL, after I precipitated the gold from the AR solution it turned from the dark green to a light blue/green colour which I tested with stannous (negative)
then the gold powder was washed and re-dissolved in HCL/CL and after i precipitated the second time is when I was left with the clear solution, hope this makes a little more sence

Rich

Thanks, Rich, and yes, it does make sense. I either missed reading that, or my old age is catching up with me. The color of your second solution is very much in keeping with what I'd have expected from a second refining.

I do have a question about the small beaker of what looks like gold chloride, however. Is that from washing, and, if so, why is there gold in solution? That shouldn't be happening.

Harold

 

[rich_2137]

The solution in the back is some foils I had dissolved earlier that day, it's a separate project (yield test)
Thanks again for all the advice and I need to remember check all solutions with stannous!

Rich