have final problem on my homework that I began but could not finish because I felt that I ran out of information. It goes as follows:
A 1.00 x10^-4 M solution of substance B has absorbances of 0.840 and 0.360 at 320 nm and 278 nm, respectively, whereas a 1.00 c 10^-4 M solution of substance C has absorbances of 0.480 and 0.432 at these wavelengths, respectively. An unknown solution has A320= 0.386 and A 278= 0.347. All these measurements were carried out under the same conditions.
a). Find which compound (B or C) exists in the unknown solution.
b). Calculate the concentration of the unknown compound.
I've figured out the molar absorptivity values at both wavelengths for both B and C. They are as follows:
B320= 8400 1/M*cm
B278= 3600 1/M*cm
C320= 4800 1/M*cm
C278= 4320 1/M*cm.
I ran stuck after figuring these. First, I thought each substance had a constant molar absorptivity, not one that varied with the wavelength of light used, so I'm not sure which of the four values I need to use. Second, it seems that there is not enough information to figure out the answer to a). I believe that if I could figure out a), I could figure out b) just by using Beer's Law. I must be missing some route, but I can not figure out what it is. Therefore, if you are willing and able to help, please do.