One milligram of a compound of molecular weight 160 is dissolved in 10 mL of ethanol, and the solution is poured into a 1-cm UV cell. The UV spectrum is taken, and there is an absorption at 𝛌_max= 247 nm.The maximum absorbance at 247 nm is 0.50. Calculate the value of𝛆 for this absorption.

Ultraviolet frequencies comprise shorter wavelengths and significant energies than the infrared frequencies. These frequencies are found beyond the visible frequencies. The wavelengths of the UV region are provided in nanometers.

Molar absorptivity computes how strongly the sample takes up light at a particular wavelength.If the sample absorbs light at a specific wavelength, the sample beam, l_s will possess less intensity than the reference beam , l_r . The ratio ofl_r tol_s will be larger than 1.

Given data:

• The molecular weight of the compound is 160 g.
• The volume of ethanol is 10 mL.
• The length of the cell is 1 cm.
• The value of λ_maxis 247 nm.
• The maximum absorbance is 0.50.

The mass of the compound can be converted to number of moles as:

1mg × 1g ∕1000mg × 1mol ∕ 160g

= 6 × 10^-6moles

The concentration can be found as:

C = 6 × 10^-6mol ∕ 10mL × 1000 mL ∕ 1L

= 6 × 10^-4M

The value of ε for this absorption can be found as:

ε = 0.50 ∕ (6 × 10^-4 )(1)

= 833 ≈ 800

Hence, the value of ε for this absorption is 800.