SusanAR Posted April 26, 2010 Share Posted April 26, 2010 :confused: We were trying to hollow a penny using a HCL solution. I needed a 6M solution,so I added 12 ml concentrated HCL (32%-38%) with 12 ml of distilled water, let the pennies soak for 3.5 hours yet nothing happened, not even any bubbles! Any idea what went wrong? Was my solution incorrect? Quote Link to comment Share on other sites More sharing options...
ChemMommy Posted April 26, 2010 Share Posted April 26, 2010 But, modern pennies have very, very little copper in them....Try an older penny, pre-1982. Quote Link to comment Share on other sites More sharing options...
Julie of KY Posted April 26, 2010 Share Posted April 26, 2010 Actually, the HCl "eats" away the zinc on the inside of the penny. If you put a new (undamaged) penny in HCl, then nothing will happen as copper is less reactive than the hydrogen in HCl, but if you damage the penny first, then the HCl can react with the zinc on the inside and hollow it out. By the way, I use undiluted HCl, but I doubt that makes any difference. (The more damaged the penny is, the faster it will react). ... what's happening is that zinc is more reactive than hydrogen, so zinc will replace the hydrogen of HCl producing H2 gas and zinc chloride in solution. Hope that helps. Quote Link to comment Share on other sites More sharing options...
SusanAR Posted April 26, 2010 Author Share Posted April 26, 2010 We used pre-1982 pennies and new pennies, and scrapped them on bricks (4 notches) to expose the inside Quote Link to comment Share on other sites More sharing options...
SusanAR Posted April 26, 2010 Author Share Posted April 26, 2010 (edited) Actually, the HCl "eats" away the zinc on the inside of the penny. If you put a new (undamaged) penny in HCl, then nothing will happen as copper is less reactive than the hydrogen in HCl, but if you damage the penny first, then the HCl can react with the zinc on the inside and hollow it out. By the way, I use undiluted HCl, but I doubt that makes any difference. (The more damaged the penny is, the faster it will react). ... what's happening is that zinc is more reactive than hydrogen, so zinc will replace the hydrogen of HCl producing H2 gas and zinc chloride in solution. Hope that helps. Yes, we thought it would be a fun demo of a single-replacement reaction. I may try undiluted HCl if I can spare enough (we still have a few other experiments this year, and I only have 30ml) Edited April 26, 2010 by SusanAR Quote Link to comment Share on other sites More sharing options...
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