Question

Examine the given Beer's Law standard curve for an unknown dye measured in a 1.0 cm cuvette. What is the molar absorptivity (in m–1cm–1) of the unknown dye at 542 nm?

Answer 1

To calculate the molar absorptivity of the unknown dye at 542 nm, the student would need the absorbance at this wavelength and the concentration of the dye. Then, applying Beer's Law (A = ε*c*l), they would solve for ε (molar absorptivity) using the known path length of 1.0 cm.

Step-by-step explanation:

The student is asking about the molar absorptivity (also known as the molar extinction coefficient) which can be derived from a Beer's Law standard curve. Beer's Law states that the absorbance (A) of a sample is directly proportional to the concentration (c) of the absorbing species in the sample, the path length (l), and the molar absorptivity (ε). The formula is A = ε*c*l. In a situation where the concentration and the path length are known, and the absorbance at a particular wavelength can be measured, the molar absorptivity can be calculated.

To calculate the molar absorptivity of an unknown dye at 542 nm using a 1.0 cm cuvette from the given Beer's Law standard curve, one would need the absorbance at 542 nm and the concentration of the dye. If the question provided the necessary data, the calculation could proceed as follows:

1. Determine the absorbance (A) at 542 nm from the standard curve.
2. Obtain the concentration (c), which should be in moles per liter (M), from the experimental conditions or prior calculations.
3. Use the known path length (l), which is given as 1.0 cm.
4. Insert these values into Beer's Law's formula (A = ε*c*l) and solve for ε (ε = A / (c*l)).

Without the actual values of absorbance and dye concentration, the molar absorptivity at 542 nm cannot be precisely calculated in this scenario. However, this is the method one would use to find the molar absorptivity if the data were available.