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.
To find the concentration of benzene in molarity, we can use the Beer-Lambert Law, which relates the absorbance of a sample to the concentration of the absorbing species.
The Beer-Lambert Law is given by the equation:
A = ε * c * l
Where:
A = Absorbance
ε = Molar absorptivity
c = Concentration
l = Path length
In this case, we are given:
A = 0.153 (absorbance)
l = 1.000 cm (path length)
To find the molar absorptivity (ε) of benzene at 256 nm, we need to consult a reference source such as a scientific journal or database.
Once we have the molar absorptivity value, we can rearrange the Beer-Lambert Law to solve for the concentration (c):
c = A / (ε * l)
Let's assume that the molar absorptivity of benzene at 256 nm is 1900 M^-1cm^-1.
Using this value, we can calculate the concentration (c):
c = 0.153 / (1900 * 1.000)
c ≈ 8.05 x 10^-5 M
Therefore, the concentration of benzene in molarity is approximately 8.05 x 10^-5 M.