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Homework Help: Another standard addition problem

  1. Sep 19, 2010 #1
    1. The problem statement, all variables and given/known data

    Palladium(II) forms an intensely colored complex at pH3.5 with arsenazo III at 660 nm. A analyst is trying to analyze the palladium content in a meteorite. First 2.534g of the meteorite was digested in strong mineral acids. The resulting solution was then evaporated into dryness, dissolved in hydrochloric acid, and separated from interference by ion chromatography. The resulting solution containing an unknown amount of Pd(II) was then diluted to 50.00ML with pH 3.5 buffer. Ten‐milliliter aliquots of this analyte solution were then transferred to 5 volumetric flasks. A standard solution was then prepared that was 1.00 ×10‐5 M in Pd(II). Volumes of the standard solution shown in the table were then pipetted into the flasks along with 10.00 mL of 0.01 M arsenazo III. Each solution was then diluted to 50.00 mL, and the absorbance of each solution was measured at 660 nm in 1.00
    cm cells.
    Volume standard addition Absorbance
    0 0.216
    5 .338
    10 0.471
    15 0.596
    20 0.764

    (a) Plot the standard‐additions plot using a spreadsheet, determine the slope and the
    intercept of the line.
    (b)Calculate the concentr
    ation of Pd (II) in the solution.
    Express the concentration of Palladium in the original meteorite in an appropriate unit.

    2. Relevant equations

    standard addition graph
    background intensity


    3. The attempt at a solution

    I can't graph this without the intensities. I dont know how to find the intensity. I can use the absorbance to calculate the transimittance but its a ratio of the intensities.
  2. jcsd
  3. Sep 19, 2010 #2


    User Avatar

    Staff: Mentor

    You don't graph concentration against intensity, but against absorbance.
    Last edited by a moderator: Aug 13, 2013
  4. Sep 19, 2010 #3
    really? Our professor really didn't tell us anything about this. We had to search for it online and apparently its a graph of concentration vs. Corrected intensity. But I will try graphing it vs absorbance
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