I\'m completely lost Please help me! I know it\'s a lot. Copper penny experiment

Question

I'm completely lost Please help me! I know it's a lot. Copper penny experiment. Pennis were used (composed of mostly copper zinc, & tin. First pennies get coated in copper off. {mixture of 20 mL of 5% acetic acid & 10g of NaCl Once penny gets cleaned in goes into beaker on a hot plate with zinc sulphate & strips of solid zinc for 10 minutes color change occurs Why does penny Change Color? Penny gets rinsed off in cool DI water placed directly on hot plate until color change Why does penny change color? Penny is put into a beaker of cool DI water penny is in color. Why does penny change color? which of these color changes are chemical or physical changes? With explanation please use chemical equation if possible would penny change Color a second time if it were hot heated on the hot plate?

Explanation / Answer

When CuCl2 (formed from CuO + acetic acid + NaCl) is mixed with Zn, Zn displaces Cu from its solution and hence the color of penny changes.

When this is washed with DI water, and heated, the color of penny changes due to oxide layer getting formed on the surface.

Penny put in DI water is now shiny as the oxide has been washed off from the xurface completely.

The penny would now not change any color If a second cycle of heating and washing is carried out as all of oxide has laready been washed off. However, keeping the penny outside for long and then repeating the cycle would show color change again.

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