How to Use This Presentation • To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.” • To advance through the presentation, click the right-arrow key or the space bar. • From the resources slide, click on any resource to see a presentation for that resource. • From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation. • You may exit the slide show at any time by pressing the Esc key. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Resources Bellringers Chapter Presentation Transparencies Standardized Test Prep Image and Math Focus Bank CNN Videos Visual Concepts Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Chemical Reactions Table of Contents Section 1 Forming New Substances Section 2 Chemical Formulas and Equations Section 3 Types of Chemical Reactions Section 4 Energy and Rates of Chemical Reactions Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Forming New Substances Bellringer What do baking bread, launching the space shuttle, and digesting food have in common? Write your answer in your science journal. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Forming New Substances Objectives • Describe how chemical reactions produce new substances that have different chemical and physical properties. • Identify four signs that indicate that a chemical reaction might be taking place. • Explain what happens to chemical bonds during a chemical reaction. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Forming New Substances Chemical Reactions • A chemical reaction is a process in which one or more substances change to make one or more new substances. • The chemical and physical properties of the new substances differ from those of the original substances. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Forming New Substances Chemical Reactions, continued • Signs of Chemical Reactions include color changes, gas formation, the formation of a precipitate (a solid substance formed in a solution), and energy given off as light, thermal energy, or electrical energy. • A Change of Properties The most important sign of a chemical reaction is the formation of new substances that have different properties. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Forming New Substances Bonds: Holding Molecules Together • A chemical bond is an attraction that holds atoms together in a molecule. • Breaking and Making Bonds If molecules bump into each other with enough energy, the chemical bonds in the molecules break. The atoms then rearrange, and new bonds form to make new substances. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Forming New Substances Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 1 Forming New Substances Bonds: Holding Molecules Together, continued • New Bonds, New Substances When new substances form, their properties differ from the properties of the starting substances. • For example, sodium is a violently reactive metal and chlorine is a greenish poisonous gas. The two elements combine to form a white solid called sodium chloride, or table salt. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Bellringer Write the following chemical symbols in your science journal. Then, try to write the names of the elements matching the symbols. H O C Na N Cl K Mg Ca Al Au F Cu Fe Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Objectives • Interpret and write simple chemical formulas. • Write and balance simple chemical equations. • Describe the basis for and the results of Lavoisier’s work with reactions. • Explain how a balanced equation shows the law of conservation of mass. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Chemical Formulas • A chemical formula is a combination of chemical symbols and numbers to represent a substance. A chemical formula shows how many atoms of each kind are present in a molecule. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Chemical Formulas and Equations Chapter 10 Chemical Formulas, continued • Writing Formulas for Covalent Compounds You can use the name of a covalent compound to write its chemical formula. The names of covalent compounds use prefixes. Each prefix represents a number, as shown below. mono- 1 hexa- 6 di- 2 hepta- 7 tri- 3 octa- 8 tetra- 4 nona- 9 penta- 5 deca- 10 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Chemical Formulas, continued • Writing Formulas for Ionic Compounds To write the formula for an ionic compound, make sure the compound’s charge is 0. • The formula must have subscripts that cause the charges of the ions to cancel out. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Chemical Equations • Describing Reactions by Using Equations A chemical equation uses chemical symbols and formulas as a shortcut to describe a chemical reaction. • From Reactants to Products The starting materials in a reaction are reactants. The substances formed from a reaction are products. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Chemical Equations, continued • The Importance of Accuracy The symbol or formula for each substance in a chemical equation must be written correctly or it will not correctly describe the reaction. The images below show how formulas and symbols can be confused. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Balancing Chemical Equations • To correctly write a chemical equation, the equation must be balanced. To understand why, you have to know about closed systems. • Nothing Goes In or Out No matter how substances in a closed system interact with each other or how they combine or break apart, the total mass of the system remains the same. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Balancing Chemical Equations, continued • Carefully Measuring Material In the 1700s, French chemist Antoine Lavoisier tested the concept of the conservation of matter. • This concept is described in the law of conservation of mass, which states that mass is neither created nor destroyed in ordinary chemical and physical changes. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Balancing Chemical Equations, continued • The Reason Equations Must Be Balanced Atoms are never lost or gained in a chemical reaction. So, a chemical equation must show the same numbers and kinds of atoms on both sides of the arrow. • When the number of atoms of each element in the reactants equals the number of atoms of those same elements in the products, the equation is balanced. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Balancing Chemical Equations, continued • How to Balance an Equation To balance an equation, you must use coefficients. • For an equation to be balanced, all atoms must be counted. So, you multiply the subscript of each element in a formula by the formula’s coefficient. • The next slide shows how to use coefficients to balance an equation. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 Types of Chemical Reactions Bellringer Are the products of a reaction always more complex than the reactants? Could products be simpler than the reactants? Explain your answers. Write your responses in your science journal. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 Types of Chemical Reactions Objectives • Describe four types of chemical reactions. • Classify a chemical equation as one of four types of chemical reactions. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 Types of Chemical Reactions Synthesis Reactions • A synthesis reaction is a reaction in which two or more substances combine to form one new compound. Decomposition Reactions • A decomposition reaction is a reaction in which a single compound breaks down to form two or more simpler substances. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 Types of Chemical Reactions Single-Displacement Reactions • A single-displacement reaction is a reaction in which an element replaces another element that is part of a compound. • Reactivity of Elements In a single-displacement reaction, a more reactive element can displace a less reactive element in a compound. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 Types of Chemical Reactions Double-Displacement Reactions • A double-displacement reaction is a reaction in which ions from two compounds exchange places. • The next slide shows models of each of the four types of chemical reactions. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 3 Types of Chemical Reactions Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 4 Energy and Rates of Chemical Reactions Bellringer Now that you know a little about chemical reactions, think about the many chemical reactions that take place around you every day. Describe your favorite chemical reaction. How do you think energy is involved in the reaction? Write your answer in your science journal. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 4 Energy and Rates of Chemical Reactions Objectives • Compare exothermic and endothermic reactions. • Explain activation energy. • Interpret an energy diagram. • Describe five factors that affect the rate of a reaction. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 4 Energy and Rates of Chemical Reactions Reactions and Energy • By comparing the chemical energy of the reactants with the chemical energy of the products, you can decide if energy is released or absorbed in the reaction. • Exothermic Reactions are reactions in which energy is released. Energy can be released as light, electrical energy, or thermal energy. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 4 Energy and Rates of Chemical Reactions Reactions and Energy, continued • Endothermic Reactions are reactions in which energy is taken in. • The Law of Conservation of Energy states that energy cannot be created or destroyed. The energy released in exothermic reactions was first stored in the chemical bonds of the reactants. And the energy taken in during endothermic reactions is stored in the products. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 4 Energy and Rates of Chemical Reactions Rates of Reactions • The speed at which new particles form is called the rate of a reaction. • Activation Energy is the smallest amount of energy that molecules need to react. A chemical reaction needs a boost of energy greater than or equal to the activation energy before the reaction can start. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 4 Energy and Rates of Chemical Reactions Rates of Reactions, continued • Sources of Activation Energy Some sources include friction, electric sparks, and light. • The next slide shows how activation energy relates to exothermic and endothermic reactions. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 4 Energy and Rates of Chemical Reactions Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 4 Energy and Rates of Chemical Reactions Factors Affecting Rates of Reactions • Temperature A higher temperature causes a faster rate of reaction. • Concentration is a measure of the amount of one substance when it is dissolved in another substance. In general, a high concentration of reactants causes a fast rate of reaction. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 4 Energy and Rates of Chemical Reactions Factors Affecting Rates of Reactions, continued • Surface Area is the amount of exposed surface of a substance. Increasing the surface area of solid reactants increases the rate of a reaction. • Inhibitors are substances that slow down or stop a chemical reaction. The rate of a reaction decreases in the presence of an inhibitor. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 4 Energy and Rates of Chemical Reactions Factors Affecting Rates of Reactions, continued • Catalysts are substances that speed up a reaction without being permanently changed. Because it is not changed, a catalyst is not a reactant. • A catalyst lowers the activation energy of a reaction, which allows the reaction to happen more quickly. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 4 Energy and Rates of Chemical Reactions Factors Affecting Reaction Rate Click below to watch the Visual Concept. Visual Concept You may stop the video at any time by pressing the Esc key. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Chemical Reactions Concept Map Use the terms below to complete the concept map on the next slide. products reactants chemical equations coefficients chemical reactions chemical formulas Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Chemical Reactions Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Chemical Reactions Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Chapter 10 Show Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation Reading Read each of the passages. Then, answer the questions that follow each passage. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation Passage 1 The key to an air bag’s success during a crash is the speed at which it inflates. Inside the bag is a gas generator that contains the compounds sodium azide, potassium nitrate, and silicon dioxide. At the moment of a crash, an electronic sensor in the car detects the sudden change in speed. Continued on the next slide Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation Passage 1, continued The sensor sends a small electric current to the gas generator. This electric current provides the activation energy for the chemicals in the gas generator. The rate at which the reaction happens is very fast. In 1/25 of a second, the gas formed in the reaction inflates the bag. The air bag fills upward and outward. By filling the space between a person and the car’s dashboard, the air bag protects him or her from getting hurt. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 1. Which of the following events happens first? A The sensor sends an electric current to the gas generator. B The air bag inflates. C The air bag fills the space between the person and the dashboard. D The sensor detects a change in speed. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 1. Which of the following events happens first? A The sensor sends an electric current to the gas generator. B The air bag inflates. C The air bag fills the space between the person and the dashboard. D The sensor detects a change in speed. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 2. What provides the activation energy for the reaction to occur? F the speed of the car G the inflation of the air bag H the hot engine I the electric current from the sensor Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 2. What provides the activation energy for the reaction to occur? F the speed of the car G the inflation of the air bag H the hot engine I the electric current from the sensor Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 3. What is the purpose of this passage? A to convince the reader to wear a seat belt B to describe the series of events that inflate an air bag C to explain why air bags are an important safety feature in cars D to show how chemical reactions protect pedestrians Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 3. What is the purpose of this passage? A to convince the reader to wear a seat belt B to describe the series of events that inflate an air bag C to explain why air bags are an important safety feature in cars D to show how chemical reactions protect pedestrians Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation Passage 2 An important tool in fighting forest fires is a slimy, red goop. This mixture of powder and water is a very powerful fire retardant. The burning of trees, grass, and brush is an exothermic reaction. The fire retardant slows or stops this self-feeding reaction by increasing the activation energy for the materials to which it sticks. Continued on the next slide Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation Passage 2, continued A plane can carry between 4,500 and 11,000 L of the goop. The plane then drops it all in front of the raging flames of a forest fire when the pilot presses the button. Firefighters on the ground can gain valuable time when a fire is slowed with a fire retardant. This extra time allows the ground team to create a fire line that will finally stop the fire. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 1. Which of the following sentences best summarizes the passage? A The burning of forests and other brush is an exothermic reaction. B Dropping fire retardants ahead of a flame can help firefighters on the ground stop a fire. C Firefighters on the ground create a fire line that will help stop the fire from spreading. D The slimy, red goop used as a fire retardant is made of a mixture of powder and water. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 1. Which of the following sentences best summarizes the passage? A The burning of forests and other brush is an exothermic reaction. B Dropping fire retardants ahead of a flame can help firefighters on the ground stop a fire. C Firefighters on the ground create a fire line that will help stop the fire from spreading. D The slimy, red goop used as a fire retardant is made of a mixture of powder and water. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 2. Based on the passage, which of the following statements is a fact? F Fire retardants are always successful in putting out fires. G No more than 4,500 L of red goop are loaded onto a plane. H A fire retardant works by increasing the activation energy for the materials that it sticks on. I The burning of trees is an endothermic reaction. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 2. Based on the passage, which of the following statements is a fact? F Fire retardants are always successful in putting out fires. G No more than 4,500 L of red goop are loaded onto a plane. H A fire retardant works by increasing the activation energy for the materials that it sticks on. I The burning of trees is an endothermic reaction. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation Interpreting Graphics Use the energy diagram below to answer the questions that follow. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 1. Which letter represents the energy of the products? AA BB CC DD Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 1. Which letter represents the energy of the products? AA BB CC DD Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 2. Which letter represents the activation energy of the reaction? FA GB HC ID Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 2. Which letter represents the activation energy of the reaction? FA GB HC ID Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 3. Which of the following statements best describes the reaction represented by the graph? A The reaction is endothermic because the energy of the products is greater than the energy of the reactants. B The reaction is endothermic because the energy of the reactants is greater than the energy of the products. C The reaction is exothermic because the energy of the products is greater than the energy of the reactants. D The reaction is exothermic because the energy of the reactants is greater than the energy of the products. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 3. Which of the following statements best describes the reaction represented by the graph? A The reaction is endothermic because the energy of the products is greater than the energy of the reactants. B The reaction is endothermic because the energy of the reactants is greater than the energy of the products. C The reaction is exothermic because the energy of the products is greater than the energy of the reactants. D The reaction is exothermic because the energy of the reactants is greater than the energy of the products. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation Math Read each question, and choose the best answer. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 1. Nina has 15 pens in her backpack. She has 3 red pens, 10 black pens, and 2 blue pens. If Ben selects a pen to borrow at random, what is the probability that the pen selected is red? A 2/15 B 1/5 C 1/3 D 2/3 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 1. Nina has 15 pens in her backpack. She has 3 red pens, 10 black pens, and 2 blue pens. If Ben selects a pen to borrow at random, what is the probability that the pen selected is red? A 2/15 B 1/5 C 1/3 D 2/3 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 2. How many atoms of nitrogen, N, are in the formula for calcium nitrate, Ca(NO3)2? F3 G2 H6 I1 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 2. How many atoms of nitrogen, N, are in the formula for calcium nitrate, Ca(NO3)2? F3 G2 H6 I1 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Standardized Test Preparation Chapter 10 3. Which letter best represents the number 2 3/5 on the number line? P 0 Q 1 R S 2 3 AP BQ CR DS Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Standardized Test Preparation Chapter 10 3. Which letter best represents the number 2 3/5 on the number line? P 0 Q 1 R S 2 3 AP BQ CR DS Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 4. According to the following chemical equation, how many reactants are needed to form water and carbon dioxide? H2CO3 H2O + CO2 F one G two H three I four Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation 4. According to the following chemical equation, how many reactants are needed to form water and carbon dioxide? H2CO3 H2O + CO2 F one G two H three I four Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Section 2 Chemical Formulas and Equations Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 10 Standardized Test Preparation Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.