[CHEKAL]

I am given molar absorptivity, wavelength, cell length and concentration, am i able to gain transmittance by:

working out A using A=εCL

then pluggin this into a rearrangement of A =-logT which is 10^A= T ?

not sure about the negative sign on the last equation, thats if the process is right?

thanks 

[curiouscat]

then pluggin this into a rearrangement of A =-logT which is 10^A= T ?

[tex]
10^{-A}=T \\
[/tex]

[CHEKAL]

does this make sense to you? :

 ε = 52430 M-1 cm-1
414 nm
1.5 M solution
 3 mm cell.

A = 52430 x 1.5 x 0.3 = 23593.5

but 10^-23593.5 is such a low number for transmittance isnt it?

[curiouscat]

What's the application / substance ?

[DrCMS]

I guess the material is a dye to have that large a molar extinction coeficient value so for a quite concentrated solution you'd get a very high A value and corespondingly low T value. 

Note - I guess thar A value is way too high to be measured accurately.

[Babcock_Hall]

I agree.  The concentration could be in the micromolar range, but not in the molar range, to be realistic.

[CHEKAL]

its haemoglobin, the maximum ε is at 414 nm, as its at maximum it makes sense to not transmit very strongly due to high absorption

[curiouscat]

its haemoglobin, the maximum ε is at 414 nm, as its at maximum it makes sense to not transmit very strongly due to high absorption

How are you going to prepare a 1.5 M solution og Heamoglobin?

MW=64,500. That'd mean dissolving 96 kgs of that in a Litre, right? 

[CHEKAL]

its oxidised haemoglobin, HbO2, its just a problem question on beers law giving us some data to work with, we dont actually have to undertake the analysis. i was just asking to make sure i got the calculations right

[DrCMS]

A problem question that has no basis in reality - yeh that sounds like the thinking of way too many school/university teachers.

[curiouscat]

its oxidised haemoglobin, HbO2, its just a problem question on beers law giving us some data to work with, we dont actually have to undertake the analysis. i was just asking to make sure i got the calculations right

Just ask your teacher how you'd prepare such a solution?   

[Babcock_Hall]

Hb in red blood cells is nearly saturating.  I don't recall the concentration offhand, but it is nowhere near 1.5 M; it is probably within an order of magnitude of 1.5 mM.  I suppose it makes no difference if the only question is whether or not one could do the calculation.  BTW the other problem from the standpoint of making a realistic problem is that absorbance values above ca. 2 AU get increasingly unreliable, depending on the spectrophotometer.