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The concentration of elemental arsenic in 45 g of contaminated grain is to be determined using constant potential coulometry measured at a mercury cathode held at a potential of -0

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The concentration of elemental arsenic in 45 g of contaminated grain is to be determined using constant potential coulometry measured at a mercury cathode held at a potential of -0.350 V vs. SCE. The grain sample was extracted into 50.00 mL of acidic aqueous buffer and the resulting solution was characterized using the following coulometric reaction:

As (s) + 3 H⁺(aq) + 3e^- -> AsH3(g)

The first column in the file is time (in seconds) and the second column is current (in amps). You may assume that 100% of the current acts to convert As(s) into AsH₃(g). Determine the weight % of As in the original soil sample.