Final answer:
When HNO2 is mixed with dissolved copper, a reaction occurs that produces various products, such as nitrogen dioxide (NO2) and nitrogen monoxide (NO). The nitrate salts of the metals crystallize upon evaporation of the resultant solutions.
Step-by-step explanation:
When HNO2 is mixed with dissolved copper, a reaction occurs that produces various products depending on the concentration of the acid and the activity of the metal.
Less active metals such as copper reduce concentrated nitric acid primarily to nitrogen dioxide (NO2). The reaction of dilute nitric acid with copper produces nitrogen monoxide (NO). In each case, the nitrate salts of the metals crystallize upon evaporation of the resultant solutions.