Question

Can you help me answer 4&5?

Zinc(ll) and the ligand L forma 1:1 complex that absorbs strongly at 600 am As long as the molar concentration of L exceeds that of Zn(II) by a factor of 5. the absorbance depends only on the cation concentration Neither Zn(ll) nor L absorbs at 600 nm A solution that is 1.59 times 10^-4 M Zn(ll) and 1.00 times 10^-3 M in L has an absorbance of 0,352 in a 1.00-cm cell at 600 ran Calculate the percent transmittance of this solution the molar absorptivity of the complex. Iron (III) reacts with ion to form rod Fe(SCN)^2+ complex Sketch a photometric titration curse for Fe(III) with thiocyanate ton when a photometer with a green filler is used to collect data Please describe how- stray radiation results in dotation's from Beer's law A standard solution was diluted to give the concentrations of von shown below The Fe(ll) -1.10- complex was then formed in 5.0 mL solutions. following which each was diluted to 500 mL The following absorbance's (1.00-cm cell) were recorded at510 nm Plot the calibration curve for these data. Calculate concentration of iron for sample treated same way yielding 0.24 absorbance Why is potentially more sensitive than tome try? Tungsten-halogen, mercury and xenon are lamps can be used as light source Please discuss explain which of three would be better light source for Why do some absorbing compounds fluoresce but others do not? Which compound in each pair exhibit higher fluorescence' Explain.

Answer 1

Answer 4. (a) Why is spectrofluorometry potentially more sensitive than spectrophotometry? The key difference is that spectrofluorometry measures the intensity of Fluorescence, while spectrophotometry (absorption spectroscopy) measures the ratio of the intensities of two beams (incident and passed beams). The Fluorescence signal is directly proportional to the intensity of the excitation Source. We can increase the intensity of the excitation source (use a laser!) an d gain a subsequent increase in the fluorescence signal-potentially leading togreater sensitivity. Spectrophotometry, on the other hand, is an absorption technique. Absorption depends on the ratio of incident to passed light: Aog so simply increasing PO also increases P (b)Tungsten-Halogen lamp mostly used because Mercury and Xenon arc lamps require caution during operation because of the danger of explosion due to very high internal gas pressures and extreme heat generated during use. Never ignite a lamp outside of its housing or observe the lamp directly when it is burning (this can cause serious eye damage). Neither mercury nor xenon lamps should be handled with bare fingers in order to avoid inadvertent etching of the quartz envelope. Change bulbs only after the lamp has had sufficient time to cool. Store lamps in their shipping containers to avoid accidents.