Analysis: The average deviation describes the precision of the results. It was determined the results our group obtained for were very precise. This is because our average deviation for Keq was only 6.8 which comes out to be a 6. percent error. Due to our deviation being so low it indicates that the equilibrium constant is indeed a “constant”.
Questions: In the lab it uses the definition equilibrium constant, what is meant when equilibrium constant is referred to, is the ratio of the molar concentrations of the reactants and products for the reaction. But in order for the ratio to be accurate the system must of reached equilibrium and temperature must have stayed constant. The value of Keq obtained from all our experiments was nearly
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This calibration curve then created an equation that allowed for the unknown concentration of the FeSCN2+ ions to be determined.
When you use a spectrophotometer you should not set the wavelength of light to be the same color of the solution. This is because if you set the wavelength to be the same color of the solution then no light will be absorbed. The reason why no light will be absorbed is because the color you see is the wavelength of light that is being reflected so you must set the wavelength to be the complementary color. The wavelength of light that was chosen for the lab was 450nm which coincides with a very dark blue color. The reason why choosing a dark blue makes the most sense for this experiment is because the color of the FeSCN2+ ion was blood red.
Spectrophotometers are quite precise instruments allowing for five significant figures to be obtained. The major source of error in this lab is how small the concentration of the reagents are.
Because a spectrophotometer is very useful it can be used in more than one lab. It can be used in a lab to determine the rate law for a color-fading reaction. It can also be used in a lab focused on the visual spectrum, where one can determine how much light different colors absorb at different wavelengths.
Conclusion: The lab was completed for two main reasons. The first reason was to determine the equilibrium constant for the
3. Explain what caused the change in plasma ketone concentration over the course of the experiment.
3. Explain what caused the change in plasma ketone concentration over the course of the experiment.
A spectrophotometer’s purpose is to use colors of the light spectrum to determine the concentration of light absorbing molecules in a solution. (p.59) In this particular lab, our mission was to determine the protein concentration and the standard curve of the unknown sample of BSA. This, by preparing five dilutions of the unknown solution of BSA together with other known concentrations, and then experimenting by observing how the concentrations were passed through the spectrophotometer. The outcome resolved in the absorption levels being decreased, and this
Scientists use an instrument called a spectrometer to quantitatively determine the amount of light absorbed by a solution. The primary inner parts of a typical spectrometer are described below. The spectrometer has a light source that emits white light containing a vast mixture of different wavelengths of electromagnetic radiation. The wavelength of interest is then selected using a monochromator (“mono” meaning one and “chromate” meaning color) and an additional exit slit. The separation of white light into different colors (wavelengths) is known as diffraction. The selected light then reaches the sample and depending on how the light interacts with the chemical compound of interest, some of the light is absorbed and some passes straight through. By comparing the amount of light entering the sample (P0) with the amount of light reaching the detector (P), the spectrometer is able to tell how much light is absorbed by the sample.
The dark, navy blue colored graph represented the absorbance curve for the S1 sample. The red colored graph represented the absorbance curve for the S2 sample. The green colored graph represented the absorbance curve for the P1 sample. The purple colored graph represented the absorbance curve for the P2 sample. The gaps between the P2 curve was due to the oversaturation that led to the inconclusive spectrophotometer readings. The blue colored graph represented the absorbance curve for the P1 low salt sample. The orange colored graph represented the absorbance curve for the P2 low salt sample. The light blue colored graph represented the absorbance curve for the P1 medium salt sample. The light pink colored graph represented the absorbance curve for the P2 medium salt sample. The light green colored graph represented the absorbance curve for the P1 high salt sample. The light purple colored graph represented the absorbance curve for the P2 high salt
5. The degree of precision was to 3 significant figures obtained with the spectrophotometer. The major source of error in our experiment was not calibrating the spectrophotometer with distilled water.
C. An unknown, rectangular substance measures 3.6 cm high, 4.21 cm long, and 1.17 cm wide.
15) Obtain the boiled chloroplast suspension, mix, and transfer 3 drops to cuvette 4. Immediately cover and mix cuvette 4. Insert it into the spectrophotometer's sample holder, read the percentage transmittance, and record it in Table 4.4. Replace cuvette 4 into the incubation test tube rack. Take and record additional readings at 5, 10, and 15 minutes. Mix the cuvette's contents just prior to each readings. Remember to use cuvtte 1 occasionally to check and adjust the spectrophotometer to 100% transmittance.
• Thirdly, we tried to maintain the temperature by keeping the test tubes in a regulated room. If the temperature were to increase it would cause the kinetic energy of the sucrose solution increase and if the temperature were to decrease it would cause the kinetic energy of the sucrose solution to decrease.
3. The spectrophotometer was set at 420nm. Distilled water was also used as the ‘blank’.
In this experiment, two reactions were run to determine the molar absorptivity and the equilibrium constant of FeSCN2+. The main principles used in this lab are equilibrium, LeChatlier’s Principle, Beer’s Law and Spectrocopy. The first reaction was run to completion using LeChatier’s Principle and the second reaction was run to equilibrium. A spectrophotometer was used to measure absorbances. Using a graph of absorbance versus concentration of FeSCN2+ was used to determine that the molar absorptivity constant was 3670. Beer’s Law was used to determine that the average equilibrium constant was 33.1793.
Incorporation of assay controls included setting up a spectrophotomer and running the chart recorder with a full-scale deflection before the start of the assay. The set recorder had a corresponding value of 1 for the change in the absorbance. Therefore, prior testing was done to observe whether a change occurred in the readings. This helped to indicate that the results were valid, as they could have been affected by a fault during the setting up of the spectrophotometer. On the other hand this was considered as one of the controls for the experiment. Nevertheless, a new cuvette had to be used for each assay.
8) Steps 1 - 8 were repeated using the wavelengths of 360 nm to 900
concentration, record the absorbance readings at a fixed wavelength, and plot the absorbance vs. concentration data. The wavelength of 520 nm was selected for experiment Part
To understand this week’s experiment one must first understand what a spectroscope is and what it does. With this understanding in hand, one would gain a deeper appreciation for this lab and its intended lesson. “A spectroscope is a device that measures the spectrum of light”