How to Clean Impurities from Liquid Mercury

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Mercury is one of the few metals that are liquid at room temperature. This makes it useful in a variety of devices, including thermometers, barometers and position-dependent switches. Since mercury is a liquid, it can often pick up and carry impurities when flown through vessels or pipes. Removing these impurities is important if the mercury is to be reused in an application. You can do this with common laboratory equipment and mercurous nitrate crystals.

    Put on the gloves to protect your hands from the chemicals. The cleaning mixture will stain your hands black otherwise.

    Place the glass funnel into the bottle. Pour approximately half a liter of dirty mercury into the bottle.

    Mix 10 milliliters of water with 50 grams of mercurous nitrate crystals in the glass beaker. Pour the mixture into the bottle containing dirty mercury.

    Stopper the bottle and carefully shake the mixture for five minutes.

    Tilt the mixture into the glass dish. Since water is much less dense than mercury, it will flow into the dish first, carrying any particulate impurities. The mercurous nitrate crystals react with contaminant molecular metals and replace them with mercury. For example:

    Cu + 2HgNO3 ==> CuNO3 + 2Hg

    Roll up the paper towels and place them in the clean glass bottle. Place the filter paper at the top of the paper towels. Pour the cleaned mercury through the paper and towel and into the clean glass bottle. The filter paper will remove any remaining physical impurities and the towels will dry the mercury.

    Things You'll Need

    • Gloves
    • Glass funnel
    • 2 wide-necked glass bottles with stopper, 1/2 liter
    • 250-milliliter glass beaker
    • Mercurous nitrate crystals
    • Large glass dish
    • Filter paper
    • Paper towels


    • Mercury is extremely poisonous. Do not allow the liquid to touch bare skin.


About the Author

Samuel Markings has been writing for scientific publications for more than 10 years, and has published articles in journals such as "Nature." He is an expert in solid-state physics, and during the day is a researcher at a Russell Group U.K. university.

Photo Credits

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