Evaluation Of A Chemical Substance

After the serial dilutions of the red and blue dyes were taken, the molarity and absorbance for both dyes were calculated. Using the MiVi = MfVf equation, the concentrations for each value of the red and blue dye were separately calculated. Calculating absorbances calls for setting the correct wavelengths of light for each dye. In this case, the 470 nm wavelength for red dye and the 635 nm wavelength for blue dye was needed to find the maximum absorbances. The absorbance was found by blanking the colorimeter and entering the concentrations. After both values of the absorbances and concentrations were found, the values were then graphed in order to obtain the equation of the relationship between absorbance and concentration.

From this graph and chart we can see that the higher the concentration the higher the absorbance, all the different concentrations were tested at the same wavelength (625nm). Also we can determine our unknown substances concentration by using the absorbance we got for it. The red dot on the graph followed by the line towards the horizontal axis indicates that the concentration of fast green was 34% or 5.1x10-3.

3ml of sample was taken first flask at 4 minutes and added to the appropriate tube of sodium hydroxide, from the second flask at 4.5 minute and so on, each flask was sampled at 30 second intervals. The sampling was then repeated starting at 8,12,16 minutes. The final sample from the last flask was taken at 18.5 minutes. Once the sampling was completed, measurements of absorbance were obtained for solution in each tube at 405 nm.

The same solution of 0.5 ml BSA was then added from test tube 1 to the test tube 2 after being properly mixed, and from test tube 2 the solution was being added to test tube 3, and so forth all the way up to test tube 5, with the same exact procedure. From the last tube, we then disposed the 0.5 ml solution. After above procedures, we now labeled another test tube “blank”; 0.5 ml blank distilled water was purred into the tube with the serial dilution of 1:10. We also had a tube C labeled “unknown” with the same 0.5 ml of solution. And after adding 5ml of Coomassie Blue to each tube (1-5) and to the blank, the result of absorbance was read at 595 nm.

Time) because it had a correlation closest to 1. All three orders were graphed and a linear regression was used to see which graphed order was closest to 1. The order was determined by comparing the concentration and time to the mathematical predictions made using the integrated rate laws. Analyzing each graph and finding each correlation helped determine which graph was closest to 1. The more concentrated a solution is, the higher the absorbance of that solution. This is due to Beer’s Law. The law measures the absorbance of a solution by determining how much light passes through a solution. As the concentration of a solution increases, fewer wavelengths of light are able to pass through the concentrated solution. The absorbance at 60 seconds was 0.573 (Figure 1: Table1). To calculate the concentration (molarity), the Beer’s Law equation was used, Abs = slope(m)+b. Plugging in what is known into the Beer’s Law equation resulted in 0.573 = 3.172e+004 + 0, where the concentration is determined by M = 0.573-0/ 3.172e+004. So, the concentration at 60 seconds using the equation (M = 0.573-0 / 3.172e+004) was 1.824e-5 M. The 1st order graph resulted in k=0.006152 (Figure 1: Graph 1). Other groups also resulted in their decolorization of CV to be the 1st rate

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 purpose of this experiment is to prepare Allura Red standard solutions, use a colorimeter to measure the absorbance value of each standard solution, find the relationship between absorbance and concentration of a solution and use the results of this experiment to determine the concentration of Allura Red

First, obtain a SpectroVis Plus device and connect with its corresponding LabQuest2 device. You need to calibrate by turning on the machine, allow the inner lamp to start heating up, and prepping a blank in the process. Obtain a dry cuvette, fill it with distilled water, and place into the SpectroVis plus device. Before doing so, be sure to wipe the outside of the cuvette with a Kimwipe to clean off any fingerprints that might be present. Fingerprints will skew with the calibration. Once the device notifies you that calibration is complete, click okay and prep for the next part of the lab.

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.

Next, we took initial absorbance readings in the Spec20 at an absorbance rate of 600 nm as well as an initial color reading. Then placed one sample under red, blue, green, or white light illuminators, and one sample in the dark. The cuvette placed under the white light acted as our positive control, and the cuvette placed in the dark acted as our negative control. We took absorbance readings of each cuvette every 5 minutes until we had four readings. After the fourth and final absorbance reading, we also took a final color reading.

Experimental Methods: Experiment 1- Absorbance Analysis Collect four cuvettes and add approximately 2/3 of the allowed volume to one of the cuvettes with distilled water. Find the spectrophotometer and insert the cuvette filled with the distilled water into the spectrophotometer. It is essential that the cuvette is inserted correctly: lining up the triangle on the cuvette with the triangle on the

Apparatus: Spectrophotometer (UV-1201), cuvettes, water bath (set at 37°C), 200µl and 1000µl micropipettes and test tube

The absorbance is measured using a Plate reader and a Standard curve is generated. Also, the different types of pipetting techniques are assessed in this Assay.

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.

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