Respuesta :
Answer:
Molar absorptivity or molar extinction co-effecient = 2120.14 cm⁻¹M⁻¹
Explanation:
First convert Concentration from ppm inM or mol/l
⇒ Molar mass of KMnO₄ = 158.03 g
⇒ 4.48 ppm = 4.48 mg/l = 4.48 x 10⁻³ g/l
⇒ Molarity = [tex]\frac{4.48 X10^{-3} }{158.03X 1(lit)}[/tex] = 2.83 x 10⁻⁵ molar
Absorbance (A) = - log(T) ( T = % transmittance)
= - log(0.859)
= 0.06
According to Lambert Beer's law
ε = [tex]\frac{A}{C X l}[/tex]
or, ε = [tex]\frac{0.06}{2.83 X 10^{-5}X1 cm }[/tex]
or, ε = 2120.14 cm⁻¹M⁻¹
Where
ε = Molar absorptivity
A = absorbance
C = Molar concentration of KMnO₄ solution
l = length
Molar absorptivity of KMnO₄ at this wavelength is 2120.14 cm⁻¹M⁻¹
Given:
Molar mass of KMnO₄ = 158.03 g
4.48 ppm = 4.48 mg/l = 4.48 x 10⁻³ g/l
Molarity = = 2.83 x 10⁻⁵ molar
Absorbance (A) = - log(T) ( T = % transmittance)
(A) = - log(0.859)
(A) = 0.06
According to Lambert Beer's law:
[tex]A=E*l*c[/tex]
where,
E = Molar absorptivity
A = absorbance
c = Molar concentration of KMnO₄ solution
l = length
On substituting the values:
[tex]A=E*l*c\\\\E =\frac{A}{c*l} \\\\E=\frac{0.06}{2.83*10^{-5}*1}\\\\E=2120.14 cm^{-1}M^{-1}[/tex]
Thus, Molar absorptivity of KMnO₄ at this wavelength= 2120.14 cm⁻¹M⁻¹.
Find more information about Lambert-Beer law here:
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