Coordination Chemistry 3 Part 2 Overview Getting Started Techniques Procedure FAQ Full Lab Manual Introduction & Goals Chemistry & Background Key Questions Prelab Problems Safety Procedure In Your Write-up Experiments Index ChemLab Home		Preparing for a Kinetics Run Begin by making a solution of your cobalt complex in a 25 mL volumetric flask. You may use a small amount of warm water to help dissolve the solid, but fill the flask to the mark with room temperature deionized water. invert and shake the flask to ensure complete mixing. You can review the use of a volumetric flask with the following link. Volumetric flask To prepare for a kinetics run, measure 10 mL of your complex solution with a Mohr pipet and put it in a clean Erlenmeyer flask. The pipet page describes how to use a pipet correctly. Pipet 10 mL of the supplied solution of HNO2/NaNO2 into a second Erlenmeyer flask. Suspend both Erlenmeyer flasks, containing the two reactants, in a water bath a 35-40°C. Suspend an empty cuvet in the bath also, and wait for everything to come to the correct temperature. Set the wavelength of your spectrometer to 500 nm and calibrate it with a water blank. While you are waiting for the reactants to reach the desired temperature, prepare a diluted solution of the complex and measure its absorbance, to determine the initial absorbance value for the run. See your lab manual for details. Starting a Kinetics Run When the reactants and empty cuvet have reached the desired temperature, use a Mohr pipet to transfer 3 mL of HNO2/NaNO2 solution into the warm cuvet. Use a Mohr pipet to add 3 mL of the cobalt complex solution to the pipet. Mix the solutions thoroughly, by inverting and shaking the stoppered cuvet. When the reaction mixture is thorougly mixed, start a timer for the kinetics run. Suspend the cuvet in the water bath, to maintain its temperature at 35-40°C. Monitor the temperature of the water bath throughout the run, and keep it constant by adding additional warm water, if necessary. Measure the absorbance of the reaction mixture at 500 nm every 3 minutes, or more frequently. Plot the absorbance vs. time and continue to monitor the absorbance until you can determine which product is formed first and whether a second product is formed later. This will be a minium of 45 minutes.
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