Lab Report on Measuring the Rate of Conversion of Hydrogen Peroxide using Enzyme Catalysis
In essence, the main objective was to use chemical titration to measure and then calculate the rate of conversion of hydrogen peroxide (H2O2) to water and oxygen by using the enzyme catalase. Other purposes of the lab were; to measure the effects of changes of temperature, pH, enzymes concentration, and substrate concentration on rates of an enzyme. The lab was also an opportunity to see a catalyzed reaction in a controlled experiment. And the last objective was to learn how environmental factors affect the rate of enzyme catalyzed reactions.
Enzymes are proteins produced by living cells. They act as catalysts in biochemical reactions. A catalyst speeds up the rate of a chemical reaction and makes it possible for the reaction to occur with a lower initial input of energy. One benefit of enzyme catalysis is that the cell can carry out complex chemical activities at a relatively low temperature (AP Lab Manual).
In biochemical reactions, the enzyme, E, combines reversibly with its specific substrate, S, to form a complex ES. One result of this temporary formation is a reduction in the energy required to activate the reaction of the substrate molecule so that P, the products of the reaction are formed. In summary: E+SESE+P. The enzyme is not changed in the reaction and can break down additional substrate molecules (Lab Bench).
The enzyme used in this lab is catalase. Catalase has a molecular weight of approximately 240,000 daltons and contains four polypeptide chains, each composed of more than 500 amino acids. This enzyme occurs universally in aerobic organisms. One function of catalase within cells is to prevent the accumulation of toxic levels of H2O2 which is formed as a by-product of metabolic processes. Catalase might also take part in some of the many oxidation reactions going on and in all cells (AP Lab manual).
The primary reaction catalyzed by catalase is the decomposition of H2O2 to form water and oxygen: 2H2O22H2O+O2 (gas). This reaction occurs spontaneously, but not at a very rapid rate. Catalase speeds up the reactions moderately. In this experiment, we determined a rate for this reaction (AP Lab Manual).
We hypothesized that the rate of a reaction is determined by measuring the accumulation of one of the products or by measuring the disappearance of the substrate. We also hypothesized that the rate of the reaction is the slope of the linear part of the graph that describes the accumulation of product (or decrease in substrate) as time progresses. We based this reasoning on our knowledge of the standards of graphing. And lastly, we...