 # Determining The Unknown Concentration Of Cobalt (II) Solution

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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