how much smb ?

[arthur kierski]

i received 2lots of gold bars (with 33grams each)----one lot seemed to be 18(750) by the collor---and the other lot12 or lower(500) -i laminated and instead of puting in nitric first(my mistake),i did the dissolution (separated) with ar---both lots dissolved easily in cold ar and now i have to filter to hold the impurities and then precipitate it with smb---- i am afraid to add too much or fewer smb to each lot-----
what do i have to do?
thanks for replies
Arthur

 

[lazersteve]

i received 2lots of gold bars (with 33grams each)----one lot seemed to be 18(750) by the collor---and the other lot12 or lower(500) -i laminated and instead of puting in nitric first(my mistake),i did the dissolution (separated) with ar---both lots dissolved easily in cold ar and now i have to filter to hold the impurities and then precipitate it with smb---- i am afraid to add too much or fewer smb to each lot-----
what do i have to do?
thanks for replies
Arthur

You should notice the solution turn clear then form a dark brown cloud. The solution should change from a orange yellow color to a very clear slightly drab green color. Add in small portions with stirring until the solution is not positive to stannous. Some extra water is required to get the SMB to form SO2. Let the solution settle for 30 minutes before testing with stannous.

Steve

 

[goldsilverpro]

How much nitric did you use in the AR? Assuming 66 grams of metal, if you used much more than about 70ml-80ml, you will probably have to eliminate the excess before dropping the gold with SMB. This is best done by evaporation.

 

[arthur kierski]

every thing went well---i did as Steve said and used only 50cc of nitric acid in each solution----150hcl +50hno3 +100cc water-----the yeald was 22,5grams of gold for the first 33grams and12,5grams in the second lot-----total =35grams
thanks Steve and gsp
Arthur