3 The following data was obtained at 500 nm in a 100 cm cell

3. The following data was obtained at 500 nm in a 1.00 cm cell, for the photometric titration of 10.00 ml of a 3.4 x 105 M Pd(II) solution with 2.44 x 104 MM complexation reagent. Correctly determine the formula of the complex. (10 pts) Volume of Reagent 0.00 ml 1.00 ml 2.00 ml 3.00 ml 4.00 ml 5.00 ml 6.00 ml 7.00 ml 8.00 ml Abs 0.000 0.147 0.271 0.375 0.371 0.347 0.325 0.306 0.289 4. Why is spectrofluorometry potentially more sensitive than spectrophotometry? Even though fluorescence is a single-beam emission technique, why are most good, expensive fluorescence instruments double beam in design? Why are fluorescence instruments arranged at 90 degrees? (9 pts)

Solution

3)

we see a maximum in absorbance at 3 ml of titrant added

moles of complexing agent added = 2.44 x 10^-3 M x 3 ml

= 7.32 x 10^-4 mmol

moles of Pd(II) solution used = 3.4 x 10^-5 M x 10 ml

= 3.4 x 10^-4 mmol

ratio of moles of complexing agent/moles of Pd(II) = 7.32 x 10^-4/3.4 x 10^-4

= 2.15 or 2

So the formula of the complex becomes = [Pd(L)2]^2+ with L being the complexing agent