2 “Shame on you, Mrs. Miller, you should be more specific!” Demo: What will happen when lemon juice/salt mixture is applied to various metal objects?Hypothesis:Materials:Procedure:1. Combine “a few” spoonfuls of lemon juice andsalt.2. Sprinkle over various pieces of metal.3. Wait (a few days) and observe.“Shame on you, Mrs. Miller, you should be more specific!”
3 Chemical ReactionsA chemical reaction is the process by which atoms or groups of atoms in substances are reorganized into different substances.Clues that a chemical reaction has taken place include the production of heat or light, and formation of a gas, liquid, or solid.
4 How do you know the difference? Chemical ChangePhysical ChangeAlters a substance’s appearance, but not its composition.Same substance before AND afterEx) water boiling/freezing, paper crumbling, chopping wood, crushing a can, mixing sand and waterAlters chemical makeupNew substance(s) createdEx) rust, burning of wood, metabolizing food, baking a cake, using a battery
5 Chemical EquationsChemical formulas describe the substances in the reaction and arrows indicate the process of change.Reactants are the starting substances, on the left side of the arrow.Products are the substances formed during the reaction, on the right side of the arrow.
6 For Example:Glucose and oxygen react to form carbon dioxide and water.Label the reactantsand products
7 Balanced EquationsThe law of conservation of mass states matter cannot be created or destroyed.The number of atoms of each element on the reactant side must equal the number of atoms of the same element on the product side.
8 Practice: Balance the following chemical equations: K + B203 K2O + B HCl + NaOH NaCl + H2OCH O2 CO2 + H2ON2 + H2 NH2Al + S8 Al2S3RUST DEMO:___ O2 + ___ Fe ___ Fe2O3
14 EnzymesCatalyst - a substance that lowers the activation energy needed to start a chemical reaction.It does not increase how much product is made and it does not get used up in the reaction.Enzymes – proteins that serve as biological catalysts.
18 Enzyme-Substrate Complex The active site changes shape and forms the enzyme-substrate complex, which helps chemical bonds in the reactants to be broken and new bonds to form.Factors such as pH, temperature, and other substances affect enzyme activity.
20 JournalWhat role do enzymes play in living things? How do they help maintain homeostasis?Enzymes lower the activation energy, which speeds up chemical reactions and cellular processes. They help in maintaining homeostasis by making sure the body’s needs are met.
21 Thought QuestionWhich of the following best explains why enzymes are necessary for many cellular reactions?Enzymes supply the oxygen necessary for the reactions.Enzymes change reactants from solid to liquid during the reactions.The reactions take up too much space in the cell if enzymes are missing.The reactions are too slow to meet the needs of the cell if enzymes are missing.
22 JournalDraw a diagram of a roller coaster and write a paragraph relating the ride to activation energy and a chemical reaction.