Question

the molar absorptivity of a compound at 500 nm wavelength is 252 M^-1 cm^-1. Suppose one prepares a solution by dissolving 0.00140 moles of a solute in enough water to make 500.0 mL solution. What would be the absorbance in a 7.00 mm pathlength cell

Answer 1

Answer: The absorbance of a compound, with a molar absorptivity at 500 nm wavelength of 252 M⁻¹ cm⁻¹, prepared by dissolving 0.00140 moles of a solute in enough water to make a 500.0 mL solution, measured in a 3 .00 mm pathlength cell, is 0.212.

First, we will calculate the molarity of the compound, which is equal to the moles of solute divided by the liters of solution.

Then, we will convert 3.00 mm to cm using the conversion factor 1 cm = 10 mm.

Finally, we will calculate the absorbance of the compound using the Beer–Lambert equation.

where,

A: absorbance

ε: molar absorptivity

b: length of light path

C: molar concentration