NOTE: When substituting nitrates for nitric acid in Poorman's AR here are some handy numbers:
1. When used to dissolve gold powders use 4 mL of 31% HCl per gram of gold plus:
1.343 g NaNO3 (sodium nitrate) per gram of gold to be dissolved.
or
1.597 g KNO3 (potassium nitrate) per gram of gold to be dissolved.
2. When used to dissolve copper based scrap 4 mL of 31% HCl per gram of copper plus:
5.35 g NaNO3 per gram of copper to be dissolved.
or
6.36 g KNO3 per gram of copper to be dissolved.
3. When using NaNO3 be sure to include 1.5 mL of water in the reaction per gram of NaNO3 used. When using KNO3 be sure to include 4 mL of water per gram of KNO3 used.
*ALSO, SEE NOTE @ BOTTOM OF PAGE*
These numbers are the theoretical values. The actual required amount will vary with reaction conditions and reflux of the vapors. With good temperature control (just below boiling) and proper reflux (watch glass or condenser) the actual required amount of nitrate (or nitric) can be reduced.
The best mileage from the nitrate can be obtained when it is added in small increments during the course of the reaction. Let each addition fully react (all tiny bubbles cease and red vapor in condenser clears) before adding the next dose. Start with very small doses to avoid boil over’s. As the reaction nears completion, (all of the target metal is dissolved), add only very small amounts of the nitrate. Steve