The goal of the experiment was to determine the unknown concentration of the provided Cobalt (II) solution by using a spectrophotometer/colorimeter. The spectrophotometer was used on the unknown solution to find the concentration of Cobalt (II). The concepts used from Beer-Lambert’s Law are the absorbance and concentration of the tested solution. The equation is A=EbC. A equals absorbance, E is the constant when identifying the species measuring the wavelength, b is the thickness of the solution, and C is the concentration of the solution. E and b are both constant, which makes the concentration and the absorbance directly proportional. Results resembled the standard curve and the connection of absorbance and concentration was used to estimate …show more content…
Then we got then unknown Cobalt (II) solution and placed it in a cuvette to measure the light transmittance recording it to three decimal places. Next, the unknown solution of Cobalt (II) was placed in a 100 mL beaker and the DI water was placed in a smaller beaker to make transferring the solutions easier. For the process of transferring each solution smoothly, a pipette will be used to place the unknown solution and DI water into the 10 mL graduated cylinder. First, 100% of the unknown concentration should be placed in a test tube ready to be put in the spectroscopy. Then, using a clean pipette fill the graduated cylinder with 9 mL of the unknown solution and fill the rest with DI water using a different clean pipette until 10 mL is reached. The concentration solution is 90%, and 10% is the DI water which makes the new mixture. The mixture that was just made will then be poured into a test tube that is beside the 100% concentration of the unknown solution. The process will then be continued by pouring 8 mL unknown solution and 2 mL of DI water into the 10 mL graduated cylinder to get 80% concentration solution; which is poured in the test tube that will be placed by the 90% concentration test tube. Again, 7 mL of the unknown solution will be placed in the graduated cylinder along with 3 mL of DI water, which makes 70% concentration solution and 30% DI water. The solution will then be poured into a test tube and placed by the 80% concentration. Then, 6 mL of Cobalt (II) unknown solution was placed with a pipette into the 10 mL graduated cylinder with 4 mL of DI water. Which makes 60% of concentration solution and 40% DI water, and pour the new mixture into a test tube and place it next to the 70% concentration solution. Take 50% of the unknown solution and place it in the 10 mL graduated cylinder along with 50% DI water making the new
Make sure to use the same type of cuvette to keep the width consistent and to prevent any experimental error from arising. Obtain 5 of the same type of cuvettes and pre-rinse them thoroughly. Label them numbers one through five in increasing molarity. Then, fill each of the cuvettes with one of the five solutions you created back in Part A. We will first examine the solution that exhibits the highest concentration or molarity. Make sure to wipe the outside of the cuvette with a Kimwipe before placing into the SpectroVis Plus device. Observe the graph that is generated and make sure to take note where the maximum absorbance takes place.
Due to this fact, the concentration of copper in the solution is able to be calculated by using light absorbance. Since zinc doesn’t absorb any light, we are able to deduce that the greater the absorbance, the greater the concentration of copper.
Each stock solution was placed in a colorimeter and was tested for it Absorbance. A computer program tested and drew up the Calibration curve/linear fit equation. However, the computer could not protect potential errors. An error for determining the concentration of the diluted and undiluted, could be a skew linear fit equation. The linear fit equation could be skewed by having an inadequate ratio of the stock solution and distilled water. For example, when making stock solution 1, 0.021(L) was used instead of 0.020(L) can throw the calibration curve, resulting a skewed linear fit equation. If the “blank” was not fully clean or had left over Allura Red residue, then the “blank” was tampered with. A tampered “blank” means any comparisons with it would have a wrong Absorbance reading. However, the most likely and most effective error, is calculation. Using the wrong V1 and V2 to determine the concentration of the undiluted would affect the answer of the grams Allura Red would be consume and the amount of molecules of Allura Red. The colorimeter is adjusted to a wavelength of 470 nm is maximize the absorbance of the Allura Red. If wavelength was place at 565 nm, then Allura Red would not absorb as much color of
With these absorbance numbers a concentration curve was constructed and the unknown solution was determined by finding the point of absorbance on the curve.
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 Beers Law calibration experiment used many concentrations of crystal violet solutions. Each of these solutions were test and analyzed in order to determine the absorbance of each concentration The results were than graphed and produced a slope of 1.00E05 with an intercept of -2.21E-02.
The values of color absorbance are effective because color absorbance has a linear relationship with concentration values, which in turn, allows us to easily find concentration values for many solutions. Beer’s law describes this phenomenon since the absorbance is directly proportional to concentration. We observed that as the color absorbance increased, the concentration of the FeSCN2+ complex ion increased. This is because as the FeSCN2+ concentration increases, the blood-red color becomes darker due to more presence of the blood-red FeSCN2+ ion. Therefore, the color absorbance increases because there is more blue color absorbed by the darker red color. We then graphed the absorbance and concentration values and created a line of best fit. Using the line of best fit, we were able to predict the equilibrium concentrations of the FeSCN2+ solutions and find the change required to reach equilibrium. Since we already knew the initial concentration of FeSCN2+ and since we already found the equilibrium concentration of FeSCN2+, we can calculate the change in equilibrium. Using this data, we were able to calculate the equilibrium concentration of all of the species in this lab, since we already knew the change from the initial concentration to the equilibrium change. Q is less than K because there was no initial concentration of FeSCN2+, but after the system reached
The purpose of this lab was to determine the percent cobalt and oxalate by mass, and with that information, the empirical formula for cobalt oxalate hydrate, using the general formula Coa(C2O4)b.cH2O.
Apparatus: Spectrophotometer (UV-1201), cuvettes, water bath (set at 37°C), 200µl and 1000µl micropipettes and test tube
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.
The purpose of the experiment was to find the absorbance value and T% of cobalt (II) nitrate solutions at various wavelengths. Using Beer’s law to determine the concentration of an unknown cobalt (II) nitrate solution with the %T and A values of the known Cobalt (II) nitrate concentrations.
After this, the solution was poured into a volumetric flask just about to the 1dm3 line and then it was left there to cool to the same temperature as the room before filling precisely to the 1dm3 line with distilled water. The molar mass of CuSO4.5H20 was 249.5 so that means 249.5g of copper sulphate was needed to dissolve, in order to make a standard solution, into 1dm3of distilled water. Following this, a linear dilution of the CuSO4.5H2O was made in order to be used to make a calibration curve after using the colorimeter to write down the absorbance of each sample. A linear dilution is diluted with distilled water in order for it to make the concentration weaker and weaker. For this investigation, the dilutions made ranged from 0.01 to 0.1 M/l . It was essential to only make up 10cm3
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
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.
8) Steps 1 - 8 were repeated using the wavelengths of 360 nm to 900