Question

The molar absorptivity of a compound at 500 nm wavelength is 252 M*1cm 1. Suppose one prepares a solution by dissolving 0.00140

moles of a solute in enough water to make a 500.0 mL solution. What would be the absorbance in a 4.00 mm pathlength cell?

Answer 1

0.28

Step-by-step explanation:

The formula to calculate the absorbance of a solution is given by:

A = ε * l * c

Where:

A = absorbance

ε = molar absorptivity (L/mol cm)

l = pathlength (cm)

c = concentration (mol/L)

The molar absorptivity of the solute at 500 nm is 252 M^-1cm^-1, and the concentration of the solute in the solution is 0.00140 moles in 500.0 mL, so c = 0.00140 / 0.500 = 0.0028 M.

A = ε * l * c = 252 M^-1 cm^-1 * 4.00 mm * 0.00280 M = 2.16

So, the absorbance in a 4.00 mm pathlength cell would be 2.16.

Answer 2

A = 252 * 0.04 * 0.0028 = 0.275584

Therefore, the absorbance of the solution in a 4.00 mm pathlength cell is approximately 0.28.

Step-by-step explanation: