How do I get zinc dissolved in hydrochloric acid out of solution?

Question

I put a penny in hydrochloric acid. The copper plating floated to the top after all the zinc was in solution. I want the zinc. How do I get it out of solution?

Answer 1

The zinc will be present as Zn2+ ions.  Sodium hydroxide will not reduce the zinc back to zinc metal.  Sodium hydroxide will precipitate the zinc as Zn(OH)2, but too much will redissolve it as Na2ZnO2 or Na2Zn(OH)4.  I would suggest adding sodium carbonate instead to precipitate the zinc as zinc carbonate.  Be sure to skim off the copper before precipitating.

This will give you a pure zinc salt.  Getting this back to zinc metal is difficult - it can be smelted with carbon, but at the temperatures required, the zinc often boils off or burns off as ZnO.  If you just want to get metallic zinc out of a penny, the best way is to melt it over an alcohol lamp or gas flame.  The zinc innards will melt before the copper, and poking the copper skin with a screwdriver (or other tool) will release the molten zinc.

Answer 2

Try NaOH.

It should leave you with metalic zinc ppt.

& salt in the solution.