1. Using the graphs of the food dyes created from your data, use the Imax to determine the amount of energy required for the electronic transition in J/photon and kJ/mole. 2. Define the word excitation in the context of today's lab. 3. The molar absorptivity, absorbance of a solution was found to be 0.75 and the pathlength of the cuvette used was 10 mm. What is the concentration of the solution in units of molarity? of a particular compound is 5,674 M1*cm1. The onlu
1. Using the graphs of the food dyes created from your data, use the Imax to determine the amount of energy required for the electronic transition in J/photon and kJ/mole. 2. Define the word excitation in the context of today's lab. 3. The molar absorptivity, absorbance of a solution was found to be 0.75 and the pathlength of the cuvette used was 10 mm. What is the concentration of the solution in units of molarity? of a particular compound is 5,674 M1*cm1. The onlu
1. Using the graphs of the food dyes created from your data, use the Imax to determine the amount of energy required for the electronic transition in J/photon and kJ/mole. 2. Define the word excitation in the context of today's lab. 3. The molar absorptivity, absorbance of a solution was found to be 0.75 and the pathlength of the cuvette used was 10 mm. What is the concentration of the solution in units of molarity? of a particular compound is 5,674 M1*cm1. The onlu
General CHEMISTRY one.. Lab 8 ( Food Dye Forensic)
Please help me answer these questions
Transcribed Image Text:Experiment 8
Food Dye Forensics
Theory:
By examining the ultraviolet-visible spectrum of a solution with a distinct color (or that
absorbs light in the ultraviolet region), the wavelength of absorbed light and the energy
associated with the electronic transition can be determined. Wavelength and energy are
inversely related to one another as seen in equation 1 below; h represents Plank's constant,
6.626*10-34 J*s; c represents the speed of light, 3*108 m/s;
represents wavelength, expressed
in meters.
hc
E =
(1)
Small wavelengths such as gamma rays (some sources include nuclear radiation and the
sun) are extremely dangerous and high in energy.
penetrate the skin and even begin unfolding DNA, which can lead to cancer! However,
wavelengths that are much larger, such as radio waves, can be beamed from local radio stations
without causing any damage to humans due to their low energy. Have you ever wondered
what the radio station 92.3 means? The radio station is beaming a frequency of 92.3 MHz from
are so dangerous that they can
their broadcasting tower. Just as energy and wavelength are related to one another, so is
frequency, represented by
smaller the wavelength. Frequency is measured in units of Hertz which is synonymous with
inverse seconds (s-1).
and wavelength, equation 2. The larger the frequency: the
C = Av
(2)
So, what gives rise to the wavelength of light and how does spectrophotometry work? If
you place a sample of food dye in a cuvette (Figure 2), made of quartz, and then shine a light
through the sample, electronic transitions will occur in the molecules of each of the food dyes.
Some of the light will be absorbed by the molecules (this is what causes the electronic
transitions) and some of the light will pass through the sample and make it to the detector.
Using this information,
incident radiation from the light source. Based on the maximum(s) achieved from the graph,
the wavelength(s) of absorption of the solution can be determined. FD&C Red 40 absorbs light
at approximately 500 nm, which can be determined from the top of the peak referred to as
max, as shown in Figure 1.
of the sample can be plotted vs. the wavelength of the
41
Transcribed Image Text:Post Lab Questions:
1. Using the graphs of the food dyes created from your data, use the Imax to determine the
amount of energy required for the electronic transition in J/photon and kJ/mole.
2. Define the word excitation in the context of today's lab.
3. The molar absorptivity,
absorbance of a solution was found to be 0.75 and the pathlength of the cuvette used
was 10 mm. What is the concentration of the solution in units of molarity?
of a particular compound is 5,674 M-1*cm1. The
Vasteono
4. Solution A absorbs light at a wavelength of 525 nm. If solution B requires a larger
amount of energy to absorb light, is the wavelength of solution B larger or smaller
compared to solution A?
5. Based on what you have learned in the lab today, how do you think suntan lotion works
to protect your skin from ultraviolet radiation? (Yes, you may use google to help you
answer this question! Please include the website if you do use an external source.)
Dianeb on
lo 1odmor boc
47
Scientific analysis of crime scene evidence to determine the events of a crime. Forensic science includes analyzing biological evidence, such as DNA fingerprinting, and non-biological evidence, such as computer forensics.
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