MadSci Network: Chemistry |
It is difficult to answer your question without some more information but I'll try... Is the zinc solid? If so, the Cu2+ ions are taking electrons from the zinc, oxidizing the zinc. This process is exothermic, i.e., releasing heat. Because you have an excess of the copper ions, and the zinc is the limiting reagent, as you add more zinc, more reaction occurs and more heat is liberated.
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