Question

The absorbance of a crystal violet solution in water (density is 1.00 g/mL) is measured in a 1.0 cm cuvette. The absorbance is 0.614 and the molar absorptivity coefficient is The molecular weight of crystal violet is 407.98 g/mol. What is the molar concentration of the solution?

Answer 1

Answer : The molar concentration of solution is $7.06\times 10^{-6}mol/L$

Explanation :

Using Beer-Lambert's law :

$A=\epsilon \times C\times l$

where,

A = absorbance of solution  = 0.614

C = molar concentration of solution = ?

l = path length = 1.0 cm

$\epsilon$ = molar absorptivity coefficient = $87000M^{-1}cm^{-1}$   (assume)

Now put all the given values in the above formula, we get:

$0.614=(87000M^{-1}cm^{-1})\times C\times (1.0cm)$

$C=0.00000705747mol/L=7.06\times 10^{-6}mol/L$

Therefore, the molar concentration of solution is $7.06\times 10^{-6}mol/L$