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Chemistry LibreTexts

Clean Coins with Vinegar

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Required Training

Required PPE

UC Lab Safety Fundamentals

Lab coat, safety glasses/goggles,

nitrile gloves

Equipment

Chemicals

Crystalizing Dish or Beaker

White Vinegar (or ~5% acetic acid)

Coins

Sodium Chloride

Procedure:

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

Discussion:

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

Hazards:

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.

SOP:

N/A

Disposal (by Storeroom)

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

Acknowledgements

http://www.madsci.org/posts/archives...3842.Ch.r.html


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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