Answer:
ε = 201.5 [tex]M^{-1} cm^{-1}[/tex]
Explanation:
Given data-
mass of benzene = 25.8 mg
= 25.8×10^-3 kg
Atomic mass of benzene= 78.11 amu
volume of hexane = 250.00 ml = 0.2500 L
Absorbance = 0.266
Length of the cell = 1.00 cm
Hence concentration = [tex]\frac{25.8\times10^{-3}}{78.11\times0.25 }[/tex]
solving we get
= 0.00132 M
Formula:
A= εcl
A= absorbance
c= concentration and l= length of cell
now substituting values in the above formula
0.266= ε×0.00132×1.000
⇒ε = [tex]\frac{0.266}{0.00132\times1.000}[/tex]
⇒ε = 201.5 [tex]M^{-1} cm^{-1}[/tex]
The molar absorptivity of benzene at this wavelength is [tex]201.5M^{-1}cm^{-1}[/tex]
It states that the amount of energy absorbed or transmitted by a solution is proportional to the solution's molar absorptivity and the concentration of solute. It is given as:
[tex]A=E*l*c[/tex]
Given:
Mass of benzene = 25.8 mg = [tex]25.8*10^{-3} kg[/tex]
Atomic mass of benzene= 78.11 amu
Volume of hexane = 250.00 ml = 0.2500 L
Absorbance = 0.266
Length of the cell = 1.00 cm
To find:
Molar absorptivity =?
Calculation for concentration:
[tex]\frac{2.8*10^{-3}}{78.11*0.25} =0.00132M[/tex]
On substituting the values in above equation:
[tex]A=E*l*c\\\\0.266=E*1.000*0.00312\\\\E=201.5M^{-1}cm^{-1}[/tex]
Thus, the value for molar absorptivity of benzene at this wavelength is :[tex]201.5M^{-1}cm^{-1}[/tex].
Find more information about Beer-Lambert's law here:
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