Chemistry Writing

Framing Statement:

This writing piece is from a Chemistry Lab report. In it, there are some terms in this conclusion that are also defined in the “Background” section of the lab report which is also similar to referencing authors in the intro like in an English essay, except in this lab report I use terminology instead of authors and their works. In addition, I made sure to try and eliminate any comma splices or fragmented sentences so that my conclusion would be grammatically correct and not read poorly. This can be seen throughout the report. I also analyzed a law further in depth and connected how it had anything to do with the lab which is also comparable to referencing an outer source and developing it in an essay. The law I analyzed was Beer’s Law, and I explained what it was in the final paragraph instead of the introduction because in this lab report, our professor wanted us to explain what it was and how it connected to the lab at the end of the report instead of the beginning. This is contradictory to how most essays are outlined and written. Overall, while there are some differences in context between an English essay and a chemistry lab report summary, there are some similarities between the two that allow it to remain legible.

Writing Piece:

“Background and Beginning Questions:

The Solutions: Concentration, Color, and Absorbance lab was used to discover the characteristics of a solution based upon the light wavelengths present in the solution. A spectrometer was used to compare the wavelengths of light emitted from the experimental solution and a standard or “blank” solution. This can be done because according to the introduction of the lab, “white light contains the entire rainbow of colors, which can be individually seen with a prism or other device”(1). In the original procedure, a 1:10 dilution was created by measuring out 1.0 mL of standard and adding it to 9.0 mL of  deionized water (DI). Then three cuvettes were obtained and DI water was added to one so that it was approximately 80% full. The Vernier spectrometer was then used to determine the visible light absorbance for the wavelengths between 400 nm and 700 nm. The DI water was used as the blank solution to use as a comparison between the absorbances of the different solutions absorbances.

Questions were then asked in order to further the research of absorbances and how they may be changed. These questions were:

  1. How does the combining ratio of colors affect the absorbance of the solutions?
  2. How do yellow versus blue, when diluted by the same ratio, differ in change to absorbance?
  3. How does the dilution ratio affect absorbance for blue?

The question that I investigated with my group was number 3. How does the dilution ratio affect absorbance for blue?

Procedure: All three groups had different questions which led to different procedures. Group one combined the colors and used different percentages of color in each solution and found the absorbency. For group two, the group changed the ratio of coloring to water to different amounts three times for both blue and yellow. My group repeated the original procedure and we did this by following the steps below:

  1. Create 5 different solutions according to steps 2-6 and obtain five cuvettes.
  2. Add 1.0mL of blue coloring to 10 mL of DI water into a beaker (10%).
  3. Add 1.0mL of blue coloring to 40 mL of DI water into a different beaker (2.5%).
  4. Add 1.0mL of blue coloring to 20 mL of DI water into a different beaker (5.0%).
  5. Add 5.0mL of blue coloring to 10 mL of DI water into a different beaker (50%).
  6. Add 9.0mL of blue coloring to 10 mL of DI water into a different beaker (90%).
  7. After creating the different solutions, fill each cuvette 80% full with the different solutions.
  8. Use the vernier spectrometer to measure the peak heights or absorbances between 400nm and 700nm.
  9. Record in data table.

Evidence:

As can be seen in the tables, all of the claims are supported by its evidence. For example, group one declared that the higher the percent in the solution, a lower absorbance is found, and in Table one as the blue percentage went from 0% to 50%, the blue absorbance went from 0.634nm to 0.325nm. This also occurred for the yellow, as when the percentage went from 0% to 50%, the absorbance dropped from 0.616nm to 0.135nm. In addition, Group 2’s data supports their claim because as the ratio of blue to water increased from 1 : 9 to 2 : 8, the absorbance increased from 0.671nm to 1.438nm. This also occurred for the yellow solution when the ratio of yellow to water increased from 1 : 9 to 2 : 8, the absorbance also increased from 0.513nm to 1.419nm. Finally, the evidence showed also that in Group 3, in Table 3, as the concentration increased so did the absorbance. This is apparent because as the concentration increases from 2.5% to 90%, the absorbency also increases from 0.065nm to 2.113nm. 

Reflection:

For the most part, as a class, the absorbency of the differently colored solutions increased as the concentration of yellow or blue colors in the water increased as well. This was because as more of the color was added to the DI water, as long as the water increased just enough as well, there was more of the color to be able to be absorbed by the DI water. Beer’s Law is applicable here because it states that there is a direct linear correlation between concentration and absorbency. Thus, when the concentrations from each groups solutions increased, so did the absorbency. What was observed was fairly consistent with a few minor repetitions and points where there was very little change. There were no super unusual results other than in Table 2, all of the Peak locations for blue were in the same exact place which is very different from the other two groups. I believe that we could use our results to find the dilution ratio of a test solution because we have all of the information we need to fill out what we have and that will leave us with what we need. Since we have our peak heights and lengths of a test solution, we would work backwards to find the dilution ratio by finding the amount of liquid that the test solution was made into and then the amount of actual solute would be found after finding out what the volume was. Overall, there was a lot of data to be collected for a few tests which helped us all realize how much concentration of a substance affects the absorbance of the solution.”