Question

A light absorbing chemical has a molar absorptivity constant of 487 L/mol*cm. For a system with a 1.00 cm path length, what chemical concentration would result in a recorded % transmittance of 31.6?a. None of these b. 974 M c. 0.000649 M d. 0.00103 M e. 0.0649 M

Answer 1

Answer:

The right answer is Option d (0.00103 M).

Explanation:

The given values are:

T = 31.6

e = 487 L mol cm

length, l = 1 cm

As we know,

Absorbance,

$A=2-log_{10}(percent \ T)$

$A=2-log_{10}(31.6)$

$A=0.5003$

By using the Beer's law, we get

⇒ $A=ecl$

⇒ $c=\frac{A}{el}$

On substituting the values, we get

⇒    $=\frac{0.5003}{487\times 1}$

⇒    $=0.001027 \ \frac{mol}{L}$

⇒    $=0.00103 \ M$