Rinse spills immediately . Using tongs, grasp the penny and hold in the nitric acid for about 20 seconds. Remove penny with tongs and rinse in cold tap water. Place one teaspoon of 30-mesh zinc in second evaporating dish. Carefully add diluted sodium hydroxide to dish until liquid is about 2 cm above the zinc.
Sodium hydroxide can cause burns.
Rinse spills immediately. Using tongs, carefully place the penny on top of the zinc. Set the evaporating dish on a hot plate and gently heat the contents of the dish until the penny turns a silver color. Do not let the contents come to a boil. Using tongs, remove the evaporating dish from the hot plate.