Question

Ali had studied the complexation experiment between Iron (III) (Fe 3+ ) and Potassium thiocyanate (KSCN). He prepared 3.4X10 -5 M of complex solution and the reaction produced orange color of complex Ferrothiocyanate Fe(SCN) 2+ which has a molar absorptivity of 7.00 X 10 3 L cm -1 mol -1 . Then he used Ultraviolet–visible spectrophotometry (UV-Vis) to analyze the complex. He use a 1.00cm cuvette cell to place the complex samples, sharp and high intensity band was obtained at 580nm wavelength.

(a) Calculate the absorbance of complex Fe(SCN) 2+ at 580nm wavelength.

(b) Predict the absorbance if he increases the concentration twice in Q.3(a).

(c) Estimate the transmittance of the solution describe in Q.3(a) and (b).

(d) Then, Ali decided to prepare 4.33ppm Fe 3+ . From the concentration prepared he took 5.0mL aliquot and treated with appropriate excess of KSCN. The mixture was diluted to 50.0mL. Then he used 2.5cm cuvette cell to place the new complex samples. Predict the absorbance of resulting solution at 580nm.

Answer 1