Determining The Rate Of Reaction Lab

The purpose of this lab is to determine the rate of reaction under different circumstances. Different variables will be manipulated to discover their effects on a particular reaction. Changes in temperature, pH, and enzyme concentration are examples of factors that have the potential to affect the initial rate of an enzyme catalyzed reaction in a controlled experiment, whether it be speeding the reaction up or slowing it down. Part I of the experiment establishes a baseline that can be used to compare the results of part II and part III, which correlates with the effects of a pH change and the effects of an increase of the indicator (i.e. guaiacol), respectively.

If the amount of guaiacol is increased by a factor of two, then the reaction
The enzyme rate of the reaction can be found by calculating the slope, dividing the change in any two absorbance values by the change in the respective time values (e.g. (0.622 A - 0.497 A) / (3 min - 2 min) = 0.125 A/min). Initially, the graph starts off with a relatively high speed of enzyme activity (0.19 A/min), but as time passed by, the line gradually levels off a bit more towards a slope of zero (0.084 A/min). This can be explained using Le Chatelier’s principle, which states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change to reestablish an equilibrium. The initial conditions prior to any change can be viewed as a state of equilibrium because no reaction was occurring and therefore no products were being formed. However, once peroxidase was added to hydrogen peroxide, oxygen gas rapidly started to form and began to quickly react with guaiacol to produce tetraguaiacol in an attempt to reconstruct equilibrium. Because with every minute passing there was a larger amount of the product than the minute before coupled with a decreasing concentration of reactants, reaction rate inevitably slowed
Because a pH of 6 appears to be the optimal pH for this enzyme (0.832 A), values further away from 6 correlated with lower absorbance values in comparison to higher absorbance values with pH values closer to 6. More specifically, a pH of 3 has an absorbance value of 0.018 A and a pH of 4 has an absorbance value of 0.315 A, appearing to be nearing much closer to zero than pH of 5 and 8, which have absorbance values of 0.481 A and 0.434 A, respectively. This curve can virtually be described as a bell curve (normal model) with a pH of 6 being the center, as values further out on the curve are associated with lower absorbance values. Either way, changing the pH of a solution to become more acidic or more basic denatures the enzyme, therefore lowering the initial rate of