26.26

The standard solution was put into appropriate solutions to give the iron concentrations shown in the following table. The 1,10,phenanthrolineiron(II) complex was formed in 25.0 mL aliquots of these solutions, each of which was volumetric to 50.00 mL (see supporting material color plate 15 at the end of the book). The absorbances in the table (1.00 cm cells) were recorded at 510 nm 26.27 The method developed in problem 26.26 was used for the routine determination of iron in 25.0 mL aliquots of groundwater. Express the concentration (as ppm Fe) in samples that yield the following absorbance data (1.00 cm cells). Calculate the relative standard deviation of the result. Repeat the calculations assuming that the absorbance data are the means of three measurements. a) 0.143 b) 0.675 c) 0.068 d) 1.009 e) 1.512 f) 0.546