The molecule β-carotene has λ 450 nm, and ɛ = 15,000 m2 mol-1. Calculate the absorption (A) expected for a solution in which 0.1 mg has been dissolved in 10 ml of water (given: the molecular weight of β-carotene, C40H56, as 536) with a path length of 1 cm. Group of answer choices

Respuesta :

Answer: The absorbance for a solution is 0.0028

Explanation:

To calculate the absorption of a solution, the equation by Beer-Lambert law is used:

[tex]A=\varepsilon \times b\times C[/tex]

OR

[tex]A=\varepsilon \times b\times \frac{\text{Given mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (mL)}}[/tex]

where,

A = absorbance = ?

[tex]\varepsilon[/tex] = molar absorptivity = [/tex]15000m^2mol^{-1}L[/tex]

b = path length = 1 cm = 0.01 m                 (Conversion factor: 1 m = 100 cm)

Given mass of [tex]\beta-[/tex] carotene = 0.1 mg = 0.0001 g     (Conversion factor: 1 g = 1000 mg)

Molar mass of [tex]\beta-[/tex] carotene = 536 g/mol

Volume of solution = 10 mL

Putting values in equation 1:

[tex]A=15000\times 0.01\times \frac{0.0001\times 1000}{536\times 10}\\\\A=0.0028[/tex]

Hence, the absorbance for a solution is 0.0028