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Clean Coins with Vinegar

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    Required Training

    Required PPE

    UC Lab Safety Fundamentals

    Lab coat, safety glasses/goggles,

    nitrile gloves



    Crystalizing Dish or Beaker

    White Vinegar (or ~5% acetic acid)


    Sodium Chloride


    1. Add salt and vinegar to coins in a beaker to clean them.


    Older pennies (1856-1983) were between 88% and 95% copper. Even newer pennies have an outermost layer of pure copper (with a 97.5% zinc core). A crust is formed on these pennies, made of CuO Cu2O and CuS among other things. When reacted with dilute acetic acid, the copper (II) oxide forms the water soluble copper acetate and dissolves away. Copper I oxide is not so soluble in 5% acetic acid. The salt added adjusts the ionic strength of the solution and promotes further dissolution and speeds up the reaction


    Be careful not to spill. Spilled vinegar should be contained, absorbed, and washed down the drain with water. Please thoroughly clean any affected areas as vinegar smells strongly and sometimes causes skin irritation.



    Disposal (by Storeroom)

    Return the vinegar/copper ion solution to the dispensary for proper disposal.


    Clean Coins with Vinegar is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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