8. Circle the letter of each sentence that is correct for the graph below. Reaction Energy-Exothermic Reactants Chemical Energy Energy released Products a. The energy required to break the bonds in the reactants is greater than the energy released as the products form. b. The energy released as the products form is greater than the energy required to break the bonds in the reactants. c. The chemical energy of the reactants is greater than the chemical energy of the products d. The chemical energy of the products is greater than the chemical energy of the reactants.Phys. Sci. Reactants, Products, Exothermic, & Endothermic Worksheet: PART A - the nature of chemical reactions A chemical reaction takes place when a substance changes chemically to produce a new substance. Product 1. Caitlyn walks out of her front gate, and she notices that there is a little rust on the metal Isooctane Water Energy where there is a scratch in the paint. Is the rust an example of a chemical reaction? CBHis energy 2. Juan always crushes the aluminum cans before putting them in the recycling bin. Are the crushed cans examples of chemical reactions? 3. Krista notices that the leaves are beginning to change color from green into reds and oranges. Are the colored leaves examples of chemical reactions? The ice cubes in Steven's glass of lemonade are starting to melt. Are the melted ice cubes examples of chemical reactions? PART 2 - Chemical reactions: exothermic and endothermic Based on the picture above, classify the following reaction as endothermic or exothermic. Justify your answer. Milk Producta Beachon in an exothermic reaction, chemical In an endothermic reaction, energy is energy is released, often as heat. absorbed by the reactants and stored in the products as chemical energy. PART 3 - Identify which are the reactants, products and if the equation is endothermic or exothermic: 1. CH, + 02 -> CO, + HO + Heat Reaction: Reactants: Products:4.Which of the following stores chemical energy? a. the temperature of a substance c. the bonds of a molecule b. the density of a substance d. the nucleus of an atom 5.Which of the following occurs in an endothermic reaction but not in an exothermic reaction? a. Chemical bonds are broken. c. Molecules are formed. b. Energy is absorbed. d. Atoms are rearranged. 6.A type of reaction that produces an increase in temperature is a. endothermic. c. covalent. b. exothermic. d. nonpolar. 7.A reaction in which the products contain more chemical energy than the reactants is a. exothermic. c. endothermic. b. electrical. d. exergonic. 8.Which of these represents the release of chemical energy? a. pouring gasoline into a tank c. a toy car running down a ramp b. burning charcoal in a grill d. warming food in a microwave 9.Which of the following are the products and reactants of a chemical reaction most likely to have in common? a. atoms c. physical properties b. molecules d. chemical properties 10.Which of the following occurs when gasoline is burned? a. New elements are formed. c. New molecules are formed. b. New atoms are formed. d. All of the above PART 5 - Energy Changes in Reactions 1. What is chemical energy? 2. Chemical reactions involve the breaking of chemical bonds in the reactants and the formation of chemical bonds in the 3. Is the following sentence true or false? The formation of chemical bonds absorbs energy. 4. During a chemical reaction, energy is either released orPART 5 - Energy Changes in Reactions 1. What is chemical energy? 2. Chemical reactions involve the breaking of chemical bonds in the reactants and the formation of chemical bonds in the 3. Is the following sentence true or false? The formation of chemical bonds absorbs energy. 4. During a chemical reaction, energy is either released or 5. Is the following sentence true or false? Physical and chemical changes can be either exothermic or endothermic changes. 6. What is an exothermic reaction? 7. Is the following sentence true or false? In exothermic reactions, the energy required to break the bonds in the reactants is greater than the energy released as the products form.2. CaCO, + Heat -> CaO + CO2 Reaction: Reactants: Products: 3. Mg + 02 -> MgO + Energy Reaction: Reactants: Products: 4. H2O + CO2 + Sunlight > C.H120. + Oz Reaction: Reactants: Products: 5. KCIO: + Energy -> KCI + Oz (8) Reaction: Reactants: Products: 6. NaOH + HCI -> NaCl + HO + Heat Reaction: Reactants: Products: 7. C:His + Heat -> CcHis + CaHa Reaction: Reactants: Products: PART 4 - Chose the option that best answers each question. 1.Which of these is not a sign of a chemical reaction? a. A gas is given off. c. Heat is released. b. The material dissolves. d. A color change occurs. 2. The substance that is formed in a chemical reaction is called the a. polymer. c. radical. b. reactant. d. product. 3. The substance that is used up in a chemical reaction is called the a. polymer. C. radical. b. reactant. d. product