2 new pennies were used (composed of mostly copper, zinc, & tin. First pennies g

Question

2 new pennies were used (composed of mostly copper, zinc, & tin. First pennies get coated in copper II oxide & Obtained off. (mixture of 20 mL of 5% acetic acid & 10g NaCl. Once penny gets cleaned in goes into beaker on a hot plate with zinc sulfate & 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 Penney is shiny 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 not heated on the hot plate?

Explanation / Answer

The penny must have changed its color because an oxidation reaction. When we heat some metals, the trnasform into oxides, for exxample Zinc oxide ZnO or CuO.This compounds are colored molecules mostly brown or black colored compounds. First at all when we put the pennies into a acetic acis solution, a redox reaction wiil happen. The acetate is an oxidant and it will react with the Cu, Zn and Sn to reduce them.

for example, if we have ZnSO4 in the plate and it will be heated, the Zn will suffer a redox reaction and will form Zn0. a metalic form. that´s why the color changes.

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