G.C.1-6 Lab Report-Online Instructions PDF

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chemistry lab course work....

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G. C. 1 - 6: LABORATORY REPORT Name: Stephanie Sandler Z Number: Z23552088 Lab TA’s Name and Section Number: Guilherme Da Silva / Section 4 A statement Accountability: “I certify that this is my own work, and I understand that if I am found to be in violation of the honor code, I will be subject to the highest penalty.” SUMMARY OF THE VIDEO As the Beer’s Law lab gets introduced, we are going to be shown how to construct a calibration curve using the lab quest 2. It consists of 0.4 molar of nickel sulfate solution along with 0.32 molar, 0.2 molar, 4 molar, 0.16 molar, 0.8 molar, and distilled water. Each of them has been put into cuvettes. Next, we are going to put them into the spectrovis plus, which shines a light from one side to a detector on another side. The light that makes it through gets detected and the amount of current will tell you how much light is being absorbed and how much is being transmitted, which then can be displayed on the screen. On the screen, you click on sensors then go to calibrate then calibrate my spectrophotometer. Then put your distilled water in the lab quest and hit finish calibration. That’s going to set up a background to show how much light gets absorbed just by the cuvette itself and the distilled water along with all the different wavelengths. Once you start, you first pick your wavelength to use so you put in your most concentrated then hit play on the screen. The screen will now show all the different colors of light that are being absorbed. This shows some being absorbed in the violet spectrum and red, and the green is being transmitted, which is why that’s the color we see. Next, you pick a wavelength that’s in the visible range. Next you go to the meter tab, then go from doing the full spectrum to doing events with entries. After, you type in the concentration with units of molarity (M). Now that we have the wavelength set, it tells what the absorbance is, so we hit play and start collecting data. Each time we put one of these solutions in, it’s going to tell what the absorbance is; we start with the blank one, therefore the absorbance being about 0. Next, you type in what the concentration is which is 0 M. Next you put in the 0.8 molar solution. Now we have an absorbance which is 0.142. The concentration is 0.142 M. For each solution you do, your concentration should be going up. The last one, the 0.4 solution, should be the biggest absorbance of all of them. Our result then becomes a linear graph with a curve fit. Our coefficients from the graph is a (M) slope of 2.0844 and the y intercept is -0.023965. The correlation is 0.99476. You can find the absorbance of the unknown for Y and divide by the slope value, then get rid of the intercept value and solve for X, which will be the concentration. 0.260 is the absorbance, so you can plug it in as Y and add -0.023965 then divide by the slope, which will tell you what your concentration is. The concentration is 0.16 M.

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G. C. 1 - 6: LABORATORY REPORT In this lab, we will use the principle of Beer’s Law to determine the exact concentration of the dye in a Powerade drink solution YOU MUST SHOW ALL YOUR CALCULATIONS TO RECEIVE CREDIT FOR THEM! Proper use of significant figures and units is part of the grading. Data table for the dye solutions: Please record the absorbance values from the video posted under the instructional materials in your canvas page. SOLUTION

VOLUME OF STOCK

VOLUME OF

# 1 2 3 4 5

DYE SOLUTION (mL) 2.00 4.00 6.00 8.00 10.00

WATER (mL) 8.00 6.00 4.00 2.00 0.00

MOLARITY

ABSORBANC

0.08 M 0.16 M 0.24 M 0.32 M 0.40 M 0.21 M

E 0.155 0.351 0.528 0.730 0.808 0.427

Powdered drink solution

Data Processing 1. Calculate the molar concentrations of the diluted solutions and record them on your data sheet. 2. Draw a calibration graph of absorbance vs. concentration by using excel for these data. 3. Determine the concentration of the powdered drink solution from the excel graph. (Refer to Figure 1 and record it on your data sheet). 4. Complete Discussion Questions Show your calculations for molarity and include your graph to your lab report, you must show calculated concentration value in your calibration graph:

Calculations and Graph

*Molarity = MIVI = MFVF* Solution #1: (2.00 mL) (0.40 M) / 10.00 mL MF = 0.08 M Solution #2: (4.00 mL) (0.40 M) / 10.00 mL MF = 0.16 M Solution #3: (6.00 mL) (0.40 M) / 10.00 mL MF = 0.24 M Solution #4: (8.00 mL) (0.40 M) / 10.00 mL MF = 0.32 M Solution #5: (10.00 mL) (0.40 M) / 10.00 mL MF = 0.40 M

Calibration Curve for CuSO4 solution 0.9

0.81

0.8

f(x) = 2.12 x + 0 R² = 0.99

Absorbance

0.7

0.73

0.6

0.53

0.5 0.35

0.4 0.3 0.16

0.2 0.1 0 0

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Concentration (M)

G. C. 1 – 6: DISCUSSION QUESTIONS

1. Your TA will provide you with the correct concentration of the dye in the powdered drink solution. Calculate the percentage error for your data. % error =

(experimental value - accepted value) accepted value

× 100

Accepted = 0.24 M Experimental = 0.427 M ((0.427 M – 0.24 M) / 0.24 M) x 100 = 77.92%

2. The empirical formula for the Brilliant Blue dye is: C 37H34N2O9S3Na2 and the formula weight are 792.86g/mol. How would you prepare a 5.25 x 10 -6 M solution of Brilliant Blue dye. How many grams of the dye you need to add to a 1.00 L of water to make this solution. 5.25 x 10-6M = given mass / 792.86 g/mol * 1L Given mass = 4.162515*10-3g

3. Many dyes used in food product are classified as hazardous chemicals in their pure form. Why, then, can they be safely used in those food products? Dosage plays a big part in whether or not food products can be safely consumed. If the amount of these hazardous chemicals are ingested in low quantities, the products are harmless because they are not in their pure form because they are stabilized by other ingredients.

4. We used 630nm wavelength to carry out the absorbance measurements. What is the color of light that the powdered drink solution primarily absorbs? Well on the spectrum from 630-750 nm is considered red so this should all be absorbed....