Question #1: What are the units of absorbance? What does it mean physically when the amount of incident light is equal to the amount of transmitted light? Is the light being absorbed or transmitted? If absorbance is equal, how does the amount of incident light compare to that of the transmitted light?
Question #2: Absorbance is related to the amount of light absorbed. It is important to understand that while the absorbance value is equal to or directly proportional to the amount of light absorbed, it is not the same as the amount of light transmitted. Consider a simple example: after the light passes through the sample, where 100 photons of light pass through the sample and Jaudon photons are detected, how many photons were transmitted through the sample? How many were absorbed by the sample? Calculate the percentage of photons transmitted and the percentage of photons absorbed. Use the equation above to calculate the transmittance of the solution from the percentage of photons detected. Now, calculate the absorbance of the solution by comparing the ratio of the photons absorbed to the ratio of their absorbance values.
Prelab Question #3: Light can be described as an electromagnetic wave. Light has both particle and wave-like properties. The electric field portion of light is shown below. For simplicity, only the 310 nm and 620 nm wavelengths are shown. Which wavelength appears to be higher in energy? Explain your reasoning. Check your answer by calculating the energy in Joules and electronvolts (eV). Convert these energies to the unit 6.2415x10^18 Joules. Why do you think energies are often reported in eV? Why do you think molecular and atomic energies are often reported in eV?