 In this lesson, you will learn how to test for the presence of carbonate, sulfate, and nitrate ions. To test for carbonates, add dilute acid and bubble the gas produced through lime water. This reaction releases carbon dioxide, which turns lime water milky due to the formation of calcium carbonate. Since many carbonates are insoluble in water, you will likely be working with solids instead of solutions. To test for sulfates, add a few drops of barium chloride solution. The white precipitate formed is barium sulfate, noted for its insolubility in water. Write down the equations for the above reactions and resume the lesson once you are done. Remember to balance the equations and use the correct state symbols. Carbonate ions react with acid to produce carbon dioxide gas and water. Barium ions and sulfate ions combine to produce a barium sulfate precipitate. To test for nitrates, add sodium hydroxide and aluminum powder and heat gently in a warm water bath. Aluminum powder reduces the nitrate ion to an ammonium ion. The ammonium ion then reacts with hydroxide to release ammonia. Ammonia can be tested using a damp red litmus paper, which turns blue. You can dip a glass rod in concentrated hydrochloric acid and place it near the mouth of the reaction vessel. This should produce ammonium chloride in the form of white smoke if ammonia is present. The production of carbon dioxide from the addition of a dilute acid confirms the presence of carbonates. If a white precipitate is formed from the addition of an aqueous barium solution, this means that sulfates are present. Nitrates can be reduced to ammonium ions, which can then react with hydroxide ions to produce ammonia. Ammonia turns damp red litmus paper blue and forms a white smoke of ammonium chloride in the presence of concentrated hydrochloric acid.