Question

7. The lead level in a sample of contaminated soil was determined using atomic absorption spectrometry. A 2.0 g sample was dissolved in acid and then diluted to a total volume of 50.0 mL. The absorbance of this solution, determined in a spectrometer set at a wavelength of 218 nm, was found to be 0.20. Several standard solutions of lead were tested under the same conditions and the calibration curve shown below was generated. The concentration of lead in the soil as a % m/m was ... A- Ex lxc A= 2-log both 1.8= log ZT absu 10.0 5.0 concentration of Pb (mg L-')

Answer 1

The concentration of lead is calculated using the graph provided and detailed in attached sheet.

If the data of the calibration curve is provided in detail the concentration can be evaluated using the straight line equation y=Mx+c.

As no data is provided in question with respect to calibration curve the conc of lead is calculated by extrapolation on graph

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