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* 10^(-6)mol/L`

Explanation :

Using Beer-Lambert's law :

`A=\epsilon * C* 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))* C* (1.0cm)`

`C=0.00000705747mol/L=7.06* 10^(-6)mol/L`

Therefore, the molar concentration of solution is
`7.06* 10^(-6)mol/L`