Here is some specific information you need to include for this pre-lab assignment:
1. You will need to show how to perform parallel and serial dilution calculations. You can assume the stock concentration of the dye is to be 0.1 M. Depending on the molar absorptivity value of each dye, the concentrations you use may vary, you can use any concentration within the range of 0.01 M to 0.1 M. Prepare five different concentrations (total volume can range from 5-50 mL) using parallel and serial dilutions.
2. Describe how to use the UV-Vis spectrometer. Describe the steps. What will you use as a blank?
To assist you with understanding serial dilutions, click on the link below for a YouTube video:
In this section, you will need to submit a typed Word document answering all of the post lab summary questions provided in Page 21 in the lab manual (There are five questions, skip Question 6 in Page 22, each question is worth 4 points, total 20 points)and use the absorbance and concentration data below to create two calibration plots, one from serial dilution and the other from parallel dilution (10 points each). The calibration plots must have the correct title of the graph,X and Y-labeling, linear equation, R-square value and slope displayed to earn full points. Make sure to include a title, your name, section number, and ALL the calculations involved with the assignment.
You can plot the graphs using Excel as demonstrated in the introductory video from this Module or in the link below and add them to the Word file for submission:
https://www.youtube.com/watch?v=i370Qr7VtUI&feature=youtu.be (Links to an external site.)
Reference: Harper College
Note: If you notice a negative slope or your X-axis is labeled as whole numbers 1,2,3,4..etc., you may have an input error in your concentration data on the spreadsheet. Excel is particular at how it recognizes numbers. If the value in the table is 1×10-4, you have to input in in Excel as either 0.0001 or 1E-04.
Table 1: Absorbance Values from Serial Dilution
| Sample | Concentration (in M) |
Absorbance @ 465 nm Trial 1 |
Absorbance @ 465 nm Trial 2 | Absorbance @ 465 nm Trial 3 | Average Absorbance |
| A | 1.25×10-4 | 1.213 | 1.096 | 1.243 | |
| B | 6.25×10-5 | 0.837 | 0.836 | 0.865 | |
| C | 3.125×10-5 | 0.492 | 0.494 | 0.492 | |
| D | 1.5625×10-5 | 0.265 | 0.270 | 0.263 | |
| E | 7.8125×10-6 | 0.146 | 0.153 | 0.148 |
* Scroll to the right to see all the data in the table
Table 2: Absorbance Values from Parallel Dilution
| Sample | Concentration (in M) | Absorbance @ 465 nm Trial 1 | Absorbance @ 465 nm Trial 2 | Absorbance @ 465 nm Trial 3 | Average Absorbance |
| A | 2.5×10-5 | 0.387 | 0.394 | 0.397 | |
| B | 5×10-5 | 0.725 | 0.733 | 0.728 | |
| C | 7.5×10-5 | 0.912 | 0.924 | 0.918 | |
| D | 1×10-4 | 1.113 | 1.152 | 1.127 | |
| E | 1.25×10-4 | 1.192 | 1.207 | 1.195 |
* Scroll to the right to see all the data in the table
See the rubric below for the criteria and the points allocated for each part. Make sure to show calculations.
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