AP Chemistry Kinetics Lab
The purpose of this lab is to learn how to write law expressions, determine orders by graphs, and calculate rate constants. By determining the number of drops of sodium hypochlorite necessary to make a diluted food dye change to colorless in less than three minutes helps calculate the absorbance which can then be analyzed to find the pseudo rate constant and eventually leading to the rate constant and the rate law. The results show that the m and n are both 1st order which makes the overall order of the blue dye 2nd order. Results:
In this experiment, rate laws and graphs help calculate the oxidation of food dyes by sodium hypochlorite. During the experiment the linear relationship between absorbance and concentration is called the Beer-Lambert Law. This law states that A=Al XBXC where A is the measured absorbance, Al is a wavelength dependent absorptivity coefficient, B is the path length, and C is the analyze concentration. The equimolar sodium chloride solution is used to dilute the sodium hypochlorite in trial 2 because these are acid base reactions, therefore distilled water would not be helpful. After graphing the plot absorbance vs. time, as shown in the graphs, whichever of three graphs produces a straight line represents the order. If absorbance vs. time is a straight line, the order is 0 and k' is the negative of the slope. If ln (absorbance) vs. time is a straight line, the order is 1 and k' is the negative of the slope. If 1/ (absorbance) vs. time is a straight line, the order is 2 and k' is the same as the slope. A rate expression is in the form r=k([A]^m)([B]^n), where [A] is the concentration of the dye and [B] is the concentration of the NaOCl.In the equation, m would be the order of reaction for the dye, and n is the order of reaction for the NaOCl.
"Chemical Reactions and Kinetics." Chemical Reactions and Kinetics. N.p., n.d. Web. 03 Sept. 2013.
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