Question

What is the concentration of copper ions (Cu2+) in a sample solution if the absorbance of the solution at a wavelength of 550 nm is 0.45 and the path length of the sample cell is 1 cm? Given that the molar absorptivity of Cu2+ at this wavelength is 1.5 × 10^4 L mol^-1 cm^-1.

Answer 1

To calculate the concentration of copper ions  Cu2+  in the sample solution, we can use the Beer-Lambert Law, which states:A =   c  lwhere A is the absorbance,  is the molar absorptivity, c is the concentration, and l is the path length.We are given the following values:A = 0.45 = 1.5  10^4 L mol^-1 cm^-1l = 1 cmWe need to solve for c  the concentration of Cu2+ ions . Rearranging the equation to solve for c, we get:c = A /    l Now, we can plug in the given values:c = 0.45 /  1.5  10^4 L mol^-1 cm^-1  1 cm c = 0.45 /  1.5  10^4 c = 3  10^-5 mol L^-1So, the concentration of copper ions  Cu2+  in the sample solution is 3  10^-5 mol L^-1.