664;2H2O+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 hypothesized that the reaction rate may be affected by temperature, pH, and activations and inhibitors. A description of several ways enzyme action may be affected follows:1. pH. Amino acid side chains contain groups such as - COOH and NH2 that readily gain or lose H+ ions. As the pH is lowered an enzyme will tend to gain H+ ions, and eventually enough side chains will be affected so the enzyme's shape is disrupted. Likewise, as the pH is raised, the enzymes will lose H+ ions and eventually lose its active shape. Many of the enzymes function properly in the neutral pH range and are denatured at either an extremely high or low pH. Some enzymes, such as pepsin, which acts in the human stomach where the pH is very low, have a low pH optimum (Enzyme Catalysis).2. Temperature. Generally, chemical reactions speed up as the temperature is raised. As the temperature increases, more of the reacting molecules have enough kinetic energy to undergo the reaction. Since enzymes are catalysts for chemical reactions, enzyme reactions also tend to go faster with increase temperature. However, if the temperature of an enzyme-catalyzed reaction is raised still further, a temperature optimum is reached; above this value the kinetic energy of the enzyme and water molecules is so great that the conformation of the enzyme molecules...
