t. But given the right conditions, iron and oxygen can react in a few seconds, as when steel wool is burned in pure oxygen. By changing the conditions in
... [Show More] which reactants meet, the rate of the chemical reaction can be altered. ● Describe how molecules interact in a chemical reaction. ● Use controlled experiments to measure the effect of four variables on a chemical reaction: temperature, concentration, surface area, and catalysts. ● Describe how a catalyst interacts with reactants in a chemical reaction. ● Describe the relationship between catalysts and enzymes. Observing a Chemical Reaction 1. What is a catalyst? What are some common biological catalysts? 2. When the two molecules meet, the resulting unstable combined molecule is called the activated complex. Describe: 3. The part of the catalyst that binds to the reactants is called the active site. a. How does the shape of the active site relate to the shapes of the two reactants? 4. How is a catalyst-reactant combination similar to a lock and key? How is it different? Factors Affecting Reaction Rates 5. What are the 4 factors that can affect the reaction rate? Make a hypothesis regarding these factors on the rate of reaction. Which one do you think will have the greatest effect on reaction rates? Out of surface area, concentration, temperature, and presence/absence of a catalyst, presence/absence of a catalyst will have the greatest effect on reaction rates. A catalyst is a substance that speeds up a chemical reaction. Common biological catalysts are enzymes. The activated complex is a short-lived, unstable arrangement of atoms that breaks apart and re-forms the reactants and can form products. The reactants, or substrates, and the active site fit together like pieces of a puzzle. They are similar because the reactant fits into the catalyst. They are different because a catalyst-reactant combination forms a product, while a lock and key refers to the shapes of the catalyst and the reactant. [Show Less]