Question

A solution has 20.0% transmittance. 10.0 mL of the solution was diluted to 20.0 mL. What is the % transmittance of the diluted solution?

Answer 1

Absorbance directly proportional to the concentration of the solution.

In the same way transmittance inversely proportional to the concentration of the solution.

Given that initial concentration = c1 = 2x

Initial transmittance T1 = 20 %

Final concentration c2 = x (decreased the concentration)

% T2 =?

T1 / T2 = e^{c2/ c1}

20/ T2 = e^{x/ 2x}

T2 = 20 / e^0.5 = 20 x e^-0.5 = 20 x e²

= 20 x 7.389 = 147.79 %

With increase in dilution the transmittance exponentially increases.