The Principles of Chemical Equilibrium, Essay Example

Introduction

The purpose of this lab was to determine the equilibrium constant of a reaction that had PrAc and H2O as products and HAc and PrOH as reactants. Sulfuric acid was used to catalyze this chemical reaction and titration was used to determine the concentration of the product. This was done to determine information regarding the rate of this particular reaction. The theory that was utilized for this study is the order of reaction and rate equation theory, which states that K = [C]^c[D]^d/[A]^a[B]^b. K is the equilibrium constant, C and D represent the products and A and B represent the reactants. The exponents represent the stoichiometric concentration of each compound. Furthermore, titration is being applied in order to gain an understanding of the concentration of the products. There is a limit to this theory because titration requires an observation of color change, and it is challenging to record the concentration of the compounds at the precise moment the indicator shows itself due to an occasional inability to control the release of the acid or base. Furthermore, the order value is not always a whole number, which complicates the precision of the calculations related to the equilibrium constant (Denbigh 1). A rate is the speed at which the products are transformed into reactants. Kinetics is a study of the speed of the reaction. The order of the reaction indicates how the concentration of substances will impact the ability of the chemical reaction to proceed at a certain rate.

Materials and Procedures

The initial reaction mixture was set up by setting up a titration involving 0.10 M NaOH, glacial acetic acid, and n-propyl. A phenopthalein indicator was used. Next, the sulfuric acid catalyst was determined and the titration steps were repeated. Last, the kinetics of the equilibrium mixture was determined performing the titration steps. The concentrations of the reactants and products were recorded and the rate equation was utilized to calculate the equilibrium constant.

Results and Discussion

Table 1: Experimental Observations and Results

The equilibrium constant of this reaction was calculated as follows:

K = [PrAc][H2O]/[HAc][PrOH]

K = (0.018)(.167)/(.020)(.167) = 0.9

This value provides information regarding the relationship between the reactants and products in the given chemical reaction. Since this number is below one, we can expect equilibrium to be reached slowly. It is important to consider, however, that this value will be different at different temperatures (Van Eldik et al. 549). If the experiment is repeated at a higher temperature, this value will be above 0.9. At a lower temperature, it will be below 0.9. This calculation appears to be accurate because the results measured for samples 1 and 2 were approximately the same. Nothing unexpected occurred in the experiment. In the future, I would conduct the experiment with an additional trial in order to enhance the accuracy of the findings. If all three trials are similar, I would have increased confidence that the results adequately describe the equilibrium of this chemical reaction.

Conclusion

The results indicated that the equilibrium constant for a reaction with HAc and PrOH as reactants and PrAc and H2O as products was K=0.9. These results appear to be accurate because the volume of NaOH used to titrate acetic acid in equilibrium mixture was similar in both samples. In addition, the concentration of the acetic acid was similar in both samples as well. It could be assumed that if the experiment were completed with additional examples, similar results would be seen in these instances as well.

Works Cited

Denbigh, K. The principles of chemical equilibrium (4th. ed.). Cambridge, U.K.: Cambridge University Press, 1981.

Van Eldik, R.; Asano, T.; Le Noble, W. J. “Activation and reaction volumes in solution”. Chemical Reviews89.3(1989): 549–688