Final answer:
To calculate the concentration of benzene in mg/mol based on absorbance, you would typically use Beer's Law. However, without the molar absorptivity of benzene at 256 nm or an alternative provided relationship, it is not possible to determine the correct concentration from the given absorbance value.
Step-by-step explanation:
The question is asking to calculate the concentration of benzene in mg/mol based on its absorbance at 256 nm in a cuvette with a 5 cm path. The information provided indicates that the molarity of benzene in a solution can be determined if we know the ppm of benzene in the said solution and the density of the solution. We are given an example where 12.7 ppm is equal to 12.7 mg per liter of solution, which helps to determine the molarity.
Using the given absorbance and path length, normally we would apply Beer's Law (A = εcl) where A is absorbance, ε is the molar absorptivity, c is concentration, and l is path length. However, in this case, we lack the molar absorptivity value needed to use this formula directly.
To proceed, we would need additional information about the molar absorptivity (ε) of benzene at 256 nm or another relationship between absorbance and concentration specific to this setup and benzene to accurately determine the concentration in mg/mol from the provided absorbance value.