======Turning Copper Coins Silver and Gold======


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====Summary====                   
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====Procedure====  
  * See links below for full method.



====Links==== 
Turn Pennies Silver and Gold (Chemistry Trick) - NurdRage: 
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Turning copper into 'silver' and 'gold' - Royal Society of Chemistry: 
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📄 Experiment - Turning Copper coins 'silver' and 'gold' - Periodic Table of Sustainable Elements: [[https://eschemistry.org/periodic-table/ExperimentTurningCoppercoinssilverandgold]]\\


====Variations====
  * Try with different copper-containing coins to compare plating results.  
  * Compare heating times to see how the depth of gold color changes.  
  * Reuse the sodium zincate solution to coat multiple coins, noting how results diminish with each reuse.



====Safety Precautions====
  * Wear safety goggles, gloves, and a lab coat at all times.  
  * Sodium hydroxide solution is extremely corrosive and can cause severe burns and blindness; handle with great care.  
  * Zinc powder is flammable; spilled powder must be cleaned up with a damp towel to prevent ignition.  
  * Hydrogen gas is flammable; add zinc to hot sodium hydroxide away from open flames.  
  * Use tongs when handling hot coins and keep a heat mat under hot equipment.  
  * Dispose of leftover sodium hydroxide solution down the drain with plenty of water only after cooling; solid zinc residue must be collected as hazardous waste.




====Questions to Consider====
  * What chemical reaction causes zinc to dissolve in sodium hydroxide? (Zn + 2NaOH + 2H₂O → Na₂[Zn(OH)₄] + H₂)  
  * Why must the coins contact zinc powder in the solution? (Direct contact establishes the electrochemical cell needed for zinc plating.)  
  * Why does the coin appear silver after plating but gold after heating? (Silver appearance is metallic zinc; heating forms brass, a gold-colored alloy of copper and zinc.)  
  * What type of alloy is brass, and how does its composition affect its properties? (Brass is a substitutional alloy of copper and zinc; higher zinc content increases strength and hardness.)  
  * How is this plating process similar to industrial galvanization? (Both involve zinc coating for corrosion resistance, but industry uses cyanide-based complexes rather than hydroxide.)