Question

A solution containing 3.75 mg/100 ml of X (335 g/mol) has a transmittance of 39.6% in a 1.50-cm cell at 425 nm. Calculate the molar absorptivity of X .

Answer 1

$A = εbc$

Concentration of A = $\dfrac{3.75 mg}{100 mL} × \dfrac{1000mL/L}{335000mg/mol} =$

$1.119 ×10^{-4} M$

$T = 0.396$

$A = - log T = - log 0.396 = 0.402$

$0.402 = ε × 1.50 cm × 1.119 ×10^{-4 }\ mol/L$

$ε = 2.4 × 10^{3} \ L/ mol. cm$