If a sample of hexane with benzene had an absorbance of 0.153 at 256 nm in a cuvette with 1.000-cm path length, find the concentration of benzene in molarity.
A = abc
A = 0.153
a = absorptivity constant. I don't see that in the problem anywhere.
b = cell length = 1 cm
c = concentration.
Find a, plug in the values and solve for c.
i didn't get the answer, i don't know how to get absorptivity constant in the following given. I just research it, the formula is 𝐴 = − log 𝑇 something like that?
No. A is not a. You need the molar absorptivity constant to plug into the formula A = abc. You're correct that 𝐴 = − log 𝑇
So, how can i find the molar absorptivity constant in the given 0.153 at 256 nm and 1.000-cm path length. Can i get absorptivity constant with the given? so that i can now find the c in the A=abc, A/ab=c right?
Nvm, i already got it, thank you so much dr bob.
To find the concentration of benzene in molarity, we need to use the Beer-Lambert Law, which relates the absorbance of a substance to its concentration.
The Beer-Lambert Law is expressed as: A = ε * l * c
Where:
A is the absorbance
ε is the molar absorptivity (or molar extinction coefficient) of the substance
l is the path length of the cuvette (in this case, 1.000 cm)
c is the concentration of the substance in molarity
In this case, we have the absorbance (A) as 0.153 and the path length (l) as 1.000 cm. We need to find the concentration of benzene (c).
To get the molar absorptivity (ε) for benzene at 256 nm, we need to refer to a reference source or a database that provides the specific molar absorptivity values for benzene at that wavelength.
Once you have the molar absorptivity value (ε) for benzene at 256 nm, you can rearrange the equation to solve for c:
c = A / (ε * l)
Plug in the values:
A = 0.153
l = 1.000 cm
Then divide by the molar absorptivity (ε) to get the concentration of benzene in molarity.