Question

What is the concentration of iron (Fe) in a sample of river water using spectrophotometric analysis with a known calibration curve and absorbance of 0.25 at a wavelength of 510 nm? The molar absorptivity of Fe at 510 nm is 8.70 x 10^3 M^-1cm^-1 and the path length of the cuvette used is 1.0 cm.

Answer 1

To determine the concentration of iron  Fe  in the river water sample, we can use the Beer-Lambert Law, which is given by:A =  * c * lwhere A is the absorbance,  is the molar absorptivity, c is the concentration of the solution, and l is the path length of the cuvette.We are given the following values:A = 0.25  absorbance at 510 nm  = 8.70 x 10^3 M^-1cm^-1  molar absorptivity of Fe at 510 nm l = 1.0 cm  path length of the cuvette We need to solve for c  concentration of Fe in the sample . Rearranging the Beer-Lambert Law equation to solve for c, we get:c = A /   * l Now, we can plug in the given values:c = 0.25 /  8.70 x 10^3 M^-1cm^-1 * 1.0 cm c = 0.25 /  8.70 x 10^3 c = 2.87 x 10^-5 MSo, the concentration of iron  Fe  in the river water sample is approximately 2.87 x 10^-5 M.