Gold penny experiment

Discussion in 'Science Technicians - General Discussion' started by EEV, Jul 12, 2019.

  1. EEV

    EEV

  2. If you scroll down the instructions in the second frame, it tells you that the 24g of NaOH is dissolved in 100ml of water and then brought to the boil. That's a very strong solution - it will probably etch the beaker and should certainly be done in a fume cupboard

    If you can't see the instructions or they won't scroll, it's a web page setup issue. It doesn't work very well here.
     
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  3. JFKtech

    JFKtech and then there were two - now JFK Techs :)

    It says in the method they need to dissolve 24g in 100mL of DI water so it's about a 6M solution
     
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  4. I'm sure I've done this just by electroplatinng the coin with Zinc then heating quickly in a bunsen but it was a while ago
     
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  5. yeah CLEAPSS PP005 has the method.
     
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  6. Electroplating doesnt give as good a result. 2M NaOH is sufficient. I dropped the molarity myself as I didnt fancy a beaker of 6M cracking whilst heating. :eek:
     
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  7. This is what we used:
    https://www.flinnsci.com/api/library/Download/674479ccda964683ac6201381ffbdb89
     
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  8. Techitude

    Techitude COMMITTEE

    We do it in the fume cupboard as it does produce some fumes although we only use 0.5M NaOH and it seems to work.
    The teacher does the zinc plating bit as a demo by boiling the sodium hydroxide and zinc powder in a big crucible then adding the pennies to turn them silver. They then hand out the 'silver' coins and the students heat them in a bunsen flame to turn them gold.

    Click here for my technician notes
     
    Last edited: Jul 12, 2019
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  9. Thank you all :)
     
  10. Julie Delaney

    Julie Delaney COMMITTEE

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  11. The nice thing about the method I've posted is that it is regarded as safer than many of the other methods which use Zinc Powder which generates Hydrogen gas which can ignite and does not require Sodium Hydroxide. The method gives excellent consistent results provided the coins are thourghly cleaned in the Vinegar and Granulated Zinc is used.



    Coin Alchemy2.png
     
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  12. That’s really helpful, thank you everyone. I will suggest the alternative method for future use.