Calculate the concentration of an anthracene solution which produced a fluorescence intensity ( I ) of 775 when the irradiance of the beam incident to the sample ( P 0 ) was 1532 and the length of the medium ( b ) was 0.875 cm. Anthracene has a molar extinction coefficient ( ϵ ) of 9.5 × 10 3 M − 1 ⋅ cm − 1 . The proportionality constant k ′ for anthracene is 0.30.

Respuesta :

Answer:

The concentration of an anthracene solution is  [tex]c = 3.560 *10^{-5}M[/tex]

Explanation:

From the question we are told that

       The incident beam [tex]P_o[/tex] is [tex]=1532[/tex]

         The fluorescence intensity is  [tex]I = 775[/tex]

          The length of the medium is b = 0.875 cm

         The molar extinction coefficient is  [tex]\epsilon = 9.5 *10^3 M^{-1} cm^{-1}[/tex]

          The proportionality  constant k = 0.30

 

According to Lambert law the Absorbance of the anthracene solution is mathematically represented as

              [tex]A = log (I_O/I)[/tex]

Where [tex]I_o =P_o[/tex]

and A  is the  Absorbance

    Substituting value

                [tex]A = log( (1532)/(775))[/tex]

                  [tex]=0.2960[/tex]

Generally beers law can be represented mathematically as

                   [tex]A = \epsilon c l[/tex]

where c is the concentration of an anthracene solution

Making c the subject of the formula

          [tex]c = \frac{A}{cl}[/tex]

Substituting  0.875 cm for length = b ,

We have  

            [tex]c = \frac{0.2960}{9.5*10^{3} * 0.875}[/tex]

              [tex]c = 3.560 *10^{-5}M[/tex]

             

The concentration of an anthracene solution is  [tex]c=3.560*10^{-5} M[/tex] which can be identified using Lambert Beer's law for absorption.

Given:

The incident beam P0= 1532

The fluorescence intensity I= 775

The length of the medium is b = 0.875 cm

The molar extinction coefficient ( ϵ ) = [tex]9.5 * 10^3 M^{-1} cm^{-1}[/tex]

The proportionality constant k = 0.30

Lambert Beer's Law:

A= ϵ *l * c

Where,

A  is the Absorbance

c is the concentration

l is the path length

( ϵ )  is the molar extinction coefficient

A= log (I₀ / I)

On adding values:

A= log (I₀ / I)

A= log (1532/775)

A= 0.2960

On substituting the values in the above formula we will get,

A= ϵ *l * c

c = A / ϵ *l

[tex]c= \frac{0.2960}{ 9.5* 10^3 *0.875}[/tex]

[tex]c=3.560*10^{-5} M[/tex]      

Thus, the concentration an anthracene solution is  [tex]c=3.560*10^{-5} M[/tex].

Find more information about Lambert Beer's law here:

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