Question

These were the steps taken in a penny experiment. My post lab is asking :

1. to identify if each of these steps resulted in a chemical or physical change.

2. Use chemical equations if possible, if you cannot write a chemical equation, explain why.

Steps of Procedure	Observations	Chemical or Physical Change
Cleaned penny with 20 mL 5% acetic acid and 10 g NaCl	Penny turned into a bright copper color
Placed penny into boiling zinc sulfate solution with solid zing strips	Color of the penny turned to a silver color
Cooled down in DI water	The silver penny became shinier
Placed on hot plate	Penny changed into a shiny gold color.

Can someone help me with writing the equations? unbalanced is ok i am pretty good at balancing.

Thanks.

Answer 1

Steps of Procedure	Observations	Chemical or Physical Change
Cleaned penny with 20 mL 5% acetic acid and 10 g NaCl	Penny turned into a bright copper color	Chemical Change: CuO + 2CH3COOH = Cu(CH3COO)2 + H2O Patina   acetic acid = copper acetate
Placed penny into boiling zinc sulfate solution with solid zing strips	Color of the penny turned to a silver color	physical change(since a layer of zinc is introduced on the penny)
Cooled down in DI water	The silver penny became shinier	Physical Change (since temperature has just cooled down)
Placed on hot plate	Penny changed into a shiny gold color.	Chemical reaction: ZnO is the gold color Zn + O2 -> ZnO