Evidence of Chemical Change: Making a solution of copper (II) nitrate into copper metal.


Evidence of chemical change: Making a solution of copper (II) nitrate into copper metal.

1. Adding dilute hydrochloric acid to copper (II) oxide and water . . .	2. . . .causes the black precipitate to dissolve and form a solution of copper (II) chloride. Once a piece of aluminum foil has been added to this solution, an exothermic reaction begins to take place slowly. As the solution gets hotter (see below) . . .
4. Mr. Mac's super-diligent students carefully record the data and observations!	3. . . . the reaction speeds up. There are two reactions taking place. The aluminum metal reacts with the excess hydrochloric acid to produce hydrogen bubbles. The aluminum also replaces the dissolved Cu²⁺ ion from solution, which causes the reddish-orange, solid copper metal to form. The blue color of the solution fades as the copper comes out of solution as a solid.