151 Online Assignment 2 Version 1

151 Online Assignment 2 Version 1

Your name: _________________________                          Your section: ____________________________

GRADE ____ /25 p

This assignent is due before 11 pm on Friday April 3^rd, 2020. The deadline is absolute. A zero will automatically apply to a late submission. You are being given more than sufficient time to complete this assignment, so please, no excuses.

All work must be well written and organized. Do not forget to title appropriately all graphs and correctly label all axes.

Assume you are working for a research lab studying the possible connection between consumption of FD&C food dyes and various attention deficit issues in children. As part of this study, you must quantify the FD&C food dyes in various packaged drinks typically consumed by children. One orange-flavored drink lists two FD&C food dyes, Yellow #5 and Red #3. Your immediate task is to quantify these dyes in the drink, as the manufacturer will not release this information.

It is known that FD&C food dye Yellow #5 (MM = 534.37 g/mol) has a λ_max = 426 nm, while Red #3 (MM = 879.86 g/mol) has a λ_max of 530 nm. You sample 3.00 mL of the orange-flavored drink into a standard polystyrene (b = 1.00 cm) cuvette and take an initial absorbance vs. wavelength (A vs. λ) absorption spectrum with a spectrophotometer identical to that of the CHEM 151 labs and following a procedure analogous to that specified in the CHEM 151 videos. The absorbance exceeds 1.00, so you dilute the orange-flavored drink by transferring 750 µL of the drink into a 1-dram vial and adding 2.25 mL of NANOpure water. This diluted sample gives an absorption spectrum that clearly shows two distinct peaks, one with λ_max = 426 nm, the other with λ_max = 530 nm. You record the absorbance values:

Absorbance vs. Wavelength (A vs. λ) Absorption Spectrum Peaks for the Diluted Orange-Flavored Drink
Peak	λmax	Absorbance, A
1	426 nm	0.349
2	530 nm	0.212

1. Preparation Tables (9p). Working with a stock solution of FD&C food dye Yellow #5 (2.71 x 10^-5 M) and another stock for FD&C food dye Red #3 (2.99 x 10^-5 M), you build two dilution sets using NANOpure water as diluent. Complete the following tables giving an example calculation.

FD&C Food Dye Yellow #5 Dilution Set Preparation
Volume of Stock (mL)	Volume of Diluent (µL)	Diluted Concentration (M)	A at λmax = 426 nm
5.00	0		0.804
2.50	2500		0.382
1.25	3750		0.185
0.62	4380		0.091
0.31	4690		0.042

 

 

 

 

FD&C Food Dye Red #3 Dilution Set Preparation
Volume of Stock (mL)	Volume of Diluent (µL)	Diluted Concentration (M)	A at λmax = 530 nm
5.00	0		0.962
2.50	2500		0.482
1.25	3750		0.246
0.62	4380		0.121
0.31	4690		0.045

 

 

 

 

 

 

2. Molar Absorptivity (8 p). Determine the molar absorptivity, ε, for the two dyes. Paste in all graphs. Include the linear trendline equation(s) and R² value(s). Clearly state the determined ε for each dye.

 

 

 

 

 

 

3. Mass of Dye per Volume (8 p). Now calculate the mass in grams (g) of dye per milliliter (mL) of orange-flavored drink. If a child consumes an average of 0.79 L of this drink per day, what is the weekly exposure of each dye from this source in milligram (mg)? To receive credit, you must present, in a highly organized fashion, all the calculations.