Question

(a) Calculate the % transmittance of a water sample with absorbance of 0.31. (b) Calculate the absorbance of a water sample with 75 % transmittance. All readings are at 254 nm.

Answer 1

The relationshiop between Absorbance and Transmittance is given as,

A = 2 - log₁₀ (%T) where A = Absorabce and % T = percent transmittance

a) given absorbance = 0.31
       A = 2 - log₁₀ (%T)
      0.31 = 2 - log₁₀ (%T)
     log₁₀ (%T) = 2 - 0.31 = 1.69
    %T = 10^1.69 = 48.97
% transmittance = 48.97

b) given % transmittance = 75
     A = 2 - log₁₀ (%T)
     A = 2 - log₁₀ (75) = 2 - 1.875 = 0.125
   absorbance = 0.125

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