help with Beer's law please?

Question

If the absorbance of a solution is 0.72 at 480 nm and it is 3.5*10^-7M, what is the value and units of eb at the wavelength at which the absorbance was read?

Answer 1

Beer's Law is:

Io/I = eCL where:

Io = Incident intensity
I = final intensity

It is important to note that Io/I will be unitless . . .

e = molar absorbance coefficient
C = concentration (M)
L = path length

Note that this equation says NOTHING about the wavelength of the incident light! That is a red herring . . .

In your example, you have Io/I and C, so rearranging the equation and substituting, you get:

eL = (Io/I) / C

eL = (0.72)/(3.5E-07M) = 2.057E06/M = 2.057E06 liter/mole

Answer 2

A = ecl
where e is called the (molar) absorptivity or extinction coefficient, c is the molar concentration of the absorbing species and l is the path length (typically 1cm for studies in aqueous solution)
then el, which is the eb is equal to
el = A/c
= 0.72/3.5*10^-7M
= 205142.857 M^-1

Answer 3

Beer's Law is A = [ ] * eb

to find eb, just divide A by [ ]

eb = 0.72 / 3.5*10^-7M = 2057142 / M

Answer 4

What is 3.5X10^ -7M? can you rephrase the question. the absorbance is 0.72@480 nm and it is 3.5X10^ -7M??? this is the expression of Beer's Law It/Io = e^epsilon(e)Cl.....t and o are just a subscript. its to hard to express in the form of equation since there is no formula bar here in yahoo answers

Answer 5

Beer's law states that after three beers, you really don't care anymore...

Sorry, I don't know the answer. Not my field of speciality. I just couldn't resist being a smarta** today.

Answer 6

after the third beer...switch to the cheap stuff.

Answer 7

" SAVE WATER , DRINK BEER "