Question

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.

Answer 1

Answer:

The concentration of an anthracene solution is  $c = 3.560 *10^{-5}M$

Explanation:

From the question we are told that

       The incident beam $P_o$ is $=1532$

         The fluorescence intensity is  $I = 775$

          The length of the medium is b = 0.875 cm

         The molar extinction coefficient is  $\epsilon = 9.5 *10^3 M^{-1} cm^{-1}$

          The proportionality  constant k = 0.30

 

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

              $A = log (I_O/I)$

Where $I_o =P_o$

and A  is the  Absorbance

    Substituting value

                $A = log( (1532)/(775))$

                  $=0.2960$

Generally beers law can be represented mathematically as

                   $A = \epsilon c l$

where c is the concentration of an anthracene solution

Making c the subject of the formula

          $c = \frac{A}{cl}$

Substituting  0.875 cm for length = b ,

We have  

            $c = \frac{0.2960}{9.5*10^{3} * 0.875}$

              $c = 3.560 *10^{-5}M$