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7.3: Activity 2 - Soil Charge

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    Name: ______________________________

    Section: _____________________________

    Student ID#:__________________________

    1) The instructor has set out two samples of the same soil and placed them into leaching tubes. Into one tube the instructor will add a solution of Eosine Yellow. Eosine Yellow is a complex organic dye with a negative electrical charge, making it an anion. Into the other tube the instructor will add a solution of Methylene Blue. Methylene Blue is a complex organic dye with a positive electrical charge, making it a cation. A sufficient amount of solution will be added to allow the accumulation of about 50 mL of leachate. Observe the color of the resulting soil in each tube and the color of leachate that came through each sample of the same soil. Record your observations in the table.

    Eosine Yellow Methylene Blue

    Color of the soil

    Color of the leachate solution

    Electrical charge on the dye

    CEC experiment questions:

    1. Which dye leached through the soil and into the leachate?
    2. What can you conclude will probably happen with other similar ions with the same electrical charge as this dye when added to the soil as fertilizers or spilled accidentally onto the soil followed by a heavy rain or water (as from irrigation or a fire truck to disperse a toxic spill of this ion)?
    3. Which dye remained attached to the soil and consequently colored the soil?
    4. What can you conclude will probably happen with other similar ions with the same electrical charge as this dye when added to the soil as fertilizers or spilled accidentally onto the soil followed by a heavy rain or water (as from irrigation or a fire truck to disperse a toxic spill of this ion)?
    5. What is the name of the process demonstrated by this experiment?

    This page titled 7.3: Activity 2 - Soil Charge is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Anna R. Schwyter & Karen L. Vaughan (UW Open Education Resources (OER)) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.