Understanding Concepts

1. Standardized Test Prep Chapter 6 Understanding Concepts 1. Mg(s) + Cl2(g) → MgCl2(s) is an example of what type of chemical reaction? A. synthesis reaction B. decomposition reaction C. single-displacement reaction D. double-displacement reaction

2. Standardized Test Prep Chapter 6 Understanding Concepts 1. Mg(s) + Cl2(g) → MgCl2(s) is an example of what type of chemical reaction? A. synthesis reaction B. decomposition reaction C. single-displacement reaction D. double-displacement reaction

3. Standardized Test Prep Chapter 6 Understanding Concepts 2. Which of the following changes will not increase the rate of a chemical reaction? F. using an enzyme in a reaction G. adding an inhibitor to the reaction mixture H. increasing the concentration of the reactants I. grinding a solid reactant to make a fine powder

4. Standardized Test Prep Chapter 6 Understanding Concepts 2. Which of the following changes will not increase the rate of a chemical reaction? F. using an enzyme in a reaction G. adding an inhibitor to the reaction mixture H. increasing the concentration of the reactants I. grinding a solid reactant to make a fine powder

5. Standardized Test Prep Chapter 6 Understanding Concepts 3. Which of the following is an endothermic chemical reaction? A. fireworks exploding in the sky B. photosynthesis in plant cells C. respiration in animal cells D. wood burning in a fireplace

6. Standardized Test Prep Chapter 6 Understanding Concepts 3. Which of the following is an endothermic chemical reaction? A. fireworks exploding in the sky B. photosynthesis in plant cells C. respiration in animal cells D. wood burning in a fireplace

7. Standardized Test Prep Chapter 6 Understanding Concepts 4. Most chemical reactions proceed faster if the reactants are heated. How does the added heat affect reactant atoms or molecules?

8. Standardized Test Prep Chapter 6 Understanding Concepts 4. Most chemical reactions proceed faster if the reactants are heated. How does the added heat affect reactant atoms or molecules? Answer: Addition of heat causes the particles to move faster and collide more often. The increase in collisions speeds up the reaction.

9. Standardized Test Prep Chapter 6 Understanding Concepts 5. The reaction of glucose and oxygen to form carbon dioxide and water produces the same amount of energy inside living cells as it does by combustion. Analyze how this reaction can occur at body temperature in the cells, but not in the open air.

10. Standardized Test Prep Chapter 6 Understanding Concepts 5. The reaction of glucose and oxygen to form carbon dioxide and water produces the same amount of energy inside living cells as it does by combustion. Analyze how this reaction can occur at body temperature in the cells, but not in the open air. Answer: Inside living cells, enzymes act as catalysts to reduce the amount of energy needed to start the reaction and to allow it to proceed at a lower temperature.

11. Standardized Test Prep Chapter 6 Reading Skills Some metals react with water to form new compounds by displacing hydrogen from water molecules. Alkali metals are sufficiently reactive that this chemical reaction happens at room temperature. If a piece of cesium is placed in water, an explosion occurs as the hydrogen gas reacts with oxygen in the air. continued on next slide

12. Standardized Test Prep Chapter 6 Reading Skills 6. Hydrogen and oxygen gases do not react spontaneously when they are mixed, unless energy is added to start the reaction. What is the source of energy that causes hydrogen to react explosively when cesium is added to water?

13. Standardized Test Prep Chapter 6 Reading Skills 6. Hydrogen and oxygen gases do not react spontaneously when they are mixed, unless energy is added to start the reaction. What is the source of energy that causes hydrogen to react explosively when cesium is added to water? Answer: The reaction of cesium and water is extremely exothermic. This exothermic reaction provides the energy to initiate the reaction between hydrogen and oxygen.

14. Standardized Test Prep Chapter 6 Interpreting Graphics 7. In each of these reactions, the chemical energy increases and then decreases, during the course of the reaction. What does the height of the “hill” on each graph represent? F. energy that must be added to start the reaction G. energy released as reactant molecules approach one another H. the potential energy of the chemical bonds in the molecules of the reactants I. The change in total chemical energy between the reactants and the products

15. Standardized Test Prep Chapter 6 Interpreting Graphics 7. In each of these reactions, the chemical energy increases and then decreases, during the course of the reaction. What does the height of the “hill” on each graph represent? F. energy that must be added to start the reaction G. energy released as reactant molecules approach one another H. the potential energy of the chemical bonds in the molecules of the reactants I. The change in total chemical energy between the reactants and the products