Lab Investigation #51 NAME__________________ Investigating Synthesis Reactions Synthesis of Copper Oxide…A synthesis reaction Procedures: 1. Determine the mass of your dry crucible and record____________. 2. Move the posies to add 5 grams to the mass of your crucible and slowly add copper till the balance levels out. 3. You now have 5 grams of copper metal in your crucible. Begin heating for ten minutes observing and recording all changes in the copper as it converts to copper oxide. 4. Periodically stir the copper to increase the exposure to the air. Use your tongs to hold the crucible and the glass rods to stir the contents 5. Copper has two oxidation states. Copper one will change the mass by 12.5 % while copper two will change the mass by 25%. 6. After cooling the copper oxide remass the dish, record the new mass of the compound you have made. Next determine if you had copper one or copper two (which mass value percent were you closer to? 7. Calculate your percent change in mass by using the formula below Percent change = change in mass of copper x 100 Original mass of copper 7. Clean up and dry your crucible. Questions: 1.Does this activity disprove the law of conservation of mass? Why or why not? 2.Write the correct chemical equation to describe this reaction. Use the appropriate oxidation number for copper based on your results. 3. Write the generalized form for a synthesis reaction. 4. List all evidences of a chemical change.