A precipitate should form when sufficient HNO 3 has been added to neutralize the amount of ammonia used to dissolve the crude product. Test a drop of the mixture with pH paper, to confirm a strongly acidic pH. The required amount of nitric acid is easily calculated. Suppose that 3 g of crude product have been dissolved in 60 mL of 1 M NH 3 . The ethanol rinses remove residual solution that contains ammonium nitrate from the solid. Ammonium nitrate is reasonably soluble in ethanol and the complex ion salt is not soluble in ethanol.
Ethanol is miscible with water and therefore serves to remove residual aqueous solution.
Allow air to pass through the solid on the filter for a few minutes, then carefully transfer the filter and solid, to a watchglass to dry. After you have cleaned up your glassware, return to your product and scrape the solid off the filter paper and onto a piece of folded weighing paper. Transfer the solid from the paper into a clean, tared glass vial. A good technique for storing a solid open to the air is to cover the vial with a kimwipe held in place with a rubber band. This system allows air drying of the solid while preventing contamination.