A mixture of X & Y in a 1 cm cell had absorbances of 0.957 at 272 nm and 0.559 at 327 nm. Find the concentrations of X & Y in the mixture.

At 21 °C, a solution of 12 mL each of 0.00200 M Fe3+ and 0.001000 M SCN- was mixed and brought to 25.0 mL with 0.1 M HNO3. The absorbance at 450 nm was measured to be 0.350 (A450 = 0.350).  This solution was then heated to 45 °C and the absorbance at 450 nm was measured to be 0.142 (A450= 0.142).    Is the reaction:  Fe3+(aq) + SCN -(aq)  →  FeSCN2+(aq) exothermic or endothermic? Explain.

Suppose that you are trying to measure the concentration of SO2 in air. To do that, you followed the para-rosaniline method. The SO2 was collected in a 10-ml solution of HgCl4 2- then diluted to 25 ml after the addition of the appropriate reagents. The absorbance owas measured at 650 nm in a 2.0-cm cell, yielding a value of 0.535. A standard sample was prepared by substituting a 1.00 mL sample of a standard solution containing the equivalent of 15.00 ppm SO2 for the airsample. The absorbance of the standard is found out to be 0.191. Report the concentration of SO2 in the air in parts per million. The density of air is 1.19 g/L

A 2.78 ✕ 10−4 M solution of a compound has an absorbance of 0.417 at 520 nm in a 1.00 cm cell. The solvent's absorbance under the same conditions is 0.020. (a) What is the molar absorptivity of the unknown compound?  M -1cm-1(b) What is the concentration of the compound in a solution, if the absorbance of the solution in a 1.00 cm cell at 520 nm is 0.391?  M