7. You are studying a reaction involving o-nitrophenol and want to keep absorption values between 0.2 and 0.8 at 410 nm. What are the lower and upper concentration limits permitted? Concentration (M) · Concentration (μM) Lower 3 3 Upper 3 3 8. You are provided with an NADH solution which you are told was a 150-fold dilution from a stock solution. You record the absorbance of your solution as 0.611 at 340 nm. What was the stock concentration? Stock concentration (M) 3 Stock concentration (mM) 3

You have two solutions of the same compound that are blue. one is very pale and the other is very intense. Absorbance of each solution was measured with a spectrophotometer at the same wave length at which the solution absorbs. (A) Which solution has the higher absorbance? (B) Which is the more concentrated solution?

Absorbance at 453 nm 8393939 7 fl. oz./20 ml Beer-Lambert's Law (Spectrophotometry) #1 Fe (aq) + KSCN(s) FESCN "(aq) + K" (aq) 3+ To determine the moles of Fe (aq) in a 100. mL sample of an unknown solution, excess KSCN(s) is added to convert all the Fe (aq) into the dark red species FeSCN"(aq), as represented by the equation above. The absorbance of FESCN"(aq) at different concentrations is shown in the graph below. 2+ 0.50 目0.40 0.30 0.20 01 0. 0. 5 x 10-5 10 x 10-5 Concentration of FESCN2+ (M) If the absorbance of the mixture is 0.20 at 453 nm, haw many moles of Fe (aq) were present in the 100. mL sample? (Assume that any volume change due to adding the KSCN(s) Iis negligible.) 3+, 4x10-4 mol 3 x 104 mol (B) 4x 10-6 mol 3x 10-6 mol

Carotenoids are yellow, orange, andred pigments synthesized by plants. Theobserved color of an object is not thecolor of light it absorbs but rather thecomplementary color, as described by acolor wheel such as the one shown here.On this wheel, complementary colorsare across from each other. (a) Based onthis wheel, what color is absorbed moststrongly if a plant is orange? (b) If a particular carotenoid absorbsphotons at 455 nm, what is the energy of the photon?