Chapter 6: Chemical Bonds

Transcription

1 Chapter 6: Chemical Bonds Section 6.1: Ionic Bonding I. Stable Electron Configurations Group # II. III. Ionic Bonds Group # A. Transfer of Electrons Group # B. Formation of Ions Group # C. Formation of Ionic Bonds Group # D. Ionization Energy Group # Ionic Compounds Group # A. Crystal Lattices Group # B. Properties of Ionic Compounds Group # Section 6.2: Covalent Bonding I. Covalent Bonds Group # A. Sharing Electrons Group #

2 II. III. B. Molecules of Elements Group # C. Multiple Covalent Bonds Group # Unequal Sharing of Electrons Group # A. Polar Covalent Bonds Group # B. Polar and Nonpolar Molecules Group # Attraction Between Molecules Group # Section 6.3: Naming Compounds and Writing Formulas I. Describing Ionic Compounds Group # A. Binary Ionic Compounds Group # B. Metals With Multiple Ions Group # C. Polyatomic Ions Group # D. Writing Formulas for Ionic Compounds Group #

3 II. Describing Molecular Compounds Group # A. Naming Molecular Compounds Group # B. Writing Molecular Formulas Group # Section 6.4: The Structure of Metals I. Metallic Bonds Group # II. III. Explaining Properties of Metals Group # Alloys Group # A. Copper Alloys Group # B. Steel Alloys Group # C. Other Alloys Group #

4 Chapter 7: Chemical Reactions Section 7.1: Describing Reactions I. Chemical Equations Group # II. III. IV. A. Using Equations to Represent Reactions Group # B. Conservation of Mass Group # Balancing Equations Group # Counting With Moles Group # A. Molar Mass Group # B. Mole-Mass Conversions Group # Chemical Calculations Group # A. Converting Mass to Moles Group # B. Using Mole Ratios Group # C. Converting Moles to Mass Group # Drawing Drawing Section 7.2: Types of Reactions I. Classifying Reactions Group #

5 A. Synthesis Group # B. Decomposition Group # C. Single Replacement Group # D. Double Replacement Group # E. Combustion Group # Drawing II. Reactions as Electron Transfers Group # A. Oxidation Group # B. Reduction Group # Section 7.3: Energy Changes in Reactions I. Chemical Bonds and Energy Group # A. Breaking Bonds Group # B. Forming Bonds Group #

6 II. Exothermic and Endothermic Reactions Group # III. A. Exothermic Reactions Group # B. Endothermic Reactions Group # Conservation of Energy Group # Section 7.4: Reaction Rates I. Reactions Over Time Group # II. Factors Affecting Reaction Rates Group # A. Temperature Group # B. Surface Area Group # C. Stirring Group # D. Catalysts Group # Section 7.5: Equilibrium I. Types of Equilibria Group # A. Physical Equilibrium Group #

7 B. Chemical Equilibrium Group # II. Factors Affecting Chemical Equilibrium Group # A. Temperature Group # B. Pressure Group # C. Concentration Group # D. Catalysts Group #

8 Chapter 6 Chemical Bonds Section 6.1 Ionic Bonding (pages ) This section describes the formation of ionic bonds and the properties of ionic compounds. Reading Strategy (page 158) Sequencing As you read, complete the concept map to show what happens to atoms during ionic bonding. For more information on this Reading Strategy, see the Reading and Study Skills in the Skills and Reference Handbook at the end of your textbook. Atom loses electrons to gains electrons to Stable Electron Configurations (page 158) 1. Describe the type of electron configuration that makes an atom stable and not likely to react. 2. Describe an electron dot diagram. Ionic Bonds (pages ) 3. Some elements achieve stable electron configurations through the transfer of between atoms. 4. By losing one valence electron, a sodium atom achieves the same electron arrangement as an atom of. 5. Circle the letter that states the result of a sodium atom transferring an electron to a chlorine atom. a. Each atom ends up with a more stable electron arrangement. b. The sodium atom becomes more stable, but the chlorine atom becomes less stable. c. The chlorine atom becomes more stable, but the sodium atom becomes less stable. d. Each atom ends up with a less stable electron arrangement. 6. Is the following sentence true or false? An ion is an atom that has a net positive or negative electric charge. 7. An ion with a negative charge is called a(n). Physical Science Guided Reading and Study Workbook Chapter 6 43

9 Chapter 6 Chemical Bonds 8. An ionic bond forms when are transferred from one atom to another. 9. Is the following sentence true or false? The lower the ionization energy, the easier it is to remove an electron from an atom. Ionic Compounds (pages ) 10. Circle the letter of each piece of information provided by the chemical formula of an ionic compound. a. which elements the compound contains b. the charge on each ion in the compound c. how the ions are arranged in the compound d. the ratio of ions in the compound 11. Circle the letter of the correct answer. The formula for magnesium chloride is MgCl 2. The charge on the magnesium ion is 2. What is the charge on each chloride ion? a. 2 b. 1 c. 0 d. 1 Na Cl 12. Look at the arrangement of ions in a sodium chloride crystal. How many sodium ions surround each chloride ion in this three-dimensional structure? a. 3 b. 4 c. 6 d The shape of an ionic crystal depends on. 14. Identify two factors that determine the arrangement of ions in an ionic crystal. a. b. 15. Is the following sentence true or false? The attractions among ions within a crystal lattice are weak. 44 Physical Science Guided Reading and Study Workbook Chapter 6

10 Chapter 6 Chemical Bonds Section 6.2 Covalent Bonding (pages ) This section discusses the formation of covalent bonds and the factors that determine whether a molecule is polar or nonpolar. It also discusses attractions between molecules. Reading Strategy (page 165) Relating Text and Visuals As you read the section, look closely at Figure 9. Complete the table by describing each type of model shown. For more information on this Reading Strategy, see the Reading and Study Skills in the Skills and Reference Handbook at the end of your textbook. Molecular Models Model Electron dot Description Structural formula Space-filling Electron cloud Covalent Bonds (pages ) 1. Describe a covalent bond. 2. Circle the letters of molecular models that show orbitals of atoms overlapping when a covalent bond forms. a. electron dot b. structural formula c. space-filling d. electron cloud 3. Describe a molecule. 4. Is the following sentence true or false? In a covalent bond, the atoms are held together by the attractions between the shared electrons and the protons in each nucleus. 5. Circle the correct answer. Nitrogen has five valence electrons. How many pairs of electrons must two nitrogen atoms share in order for each atom to have eight valence electrons? a. zero b. one c. two d. three Physical Science Guided Reading and Study Workbook Chapter 6 45

11 Chapter 6 Chemical Bonds Unequal Sharing of Electrons (pages ) 6. In general, elements at the of a group have a greater attraction for electrons than elements at the of a group have. 7. In a hydrogen chloride molecule, the shared electrons spend more time near the atom than near the atom. 8. Describe a polar covalent bond. 9. When atoms form a polar covalent bond, the atom with the greater attraction for electrons has a partial charge. 10. Is the following sentence true or false? In a molecule of a compound, electrons are always shared equally by both atoms. 11. Circle the letter of each factor that determines whether a molecule is polar or nonpolar. a. the number of atoms in the molecule b. the type of atoms in the molecule c. the number of bonds in the molecule d. the shape of the molecule CO Compare the shapes of carbon dioxide and water molecules. Circle the letter of the polar molecule. a. carbon dioxide b. water 13. Is the following sentence true or false? In a water molecule, the hydrogen side of the molecule has a partial positive charge, and the oxygen side has a partial negative charge. Attraction Between Molecules (page 169) 14. Water has a higher boiling point than carbon dioxide because attractions between polar molecules are attractions between nonpolar molecules. than 15. Is the following sentence true or false? Attractions among nonpolar molecules explain why nitrogen can be stored as a liquid at low temperatures and high pressures. H 2 O 46 Physical Science Guided Reading and Study Workbook Chapter 6

12 Chapter 6 Chemical Bonds Section 6.3 Naming Compounds and Writing Formulas (pages ) This section explains how to name and write formulas for ionic and molecular compounds. Reading Strategy (page 170) Predicting Before you read, predict the meaning of the term polyatomic ion, and write your prediction in the table. After you read, if your prediction was incorrect, revise your definition. For more information on this Reading Strategy, see the Reading and Study Skills in the Skills and Reference Handbook at the end of your textbook. Vocabulary Term Before You Read After You Read Polyatomic ion Describing Ionic Compounds (pages ) 1. Is the following sentence true or false? The name of an ionic compound must distinguish the compound from other ionic compounds containing the same elements. 2. What information is provided by the formula for an ionic compound? 3. Circle the letter of the word that describes a compound made from only two elements. a. ionic b. binary c. diatomic d. polar 4. Is the following sentence true or false? Names of anions are formed by placing the suffix -ide after part of the name of the nonmetal. 5. When a metal forms more than one ion, the name of the ion contains a Roman numeral to indicate the charge on the ion. 6. What is a polyatomic ion? 7. Is the following sentence true or false? Because all compounds are neutral, the total charges on the cations and anions in the formula of an ionic compound must add up to zero. Physical Science Guided Reading and Study Workbook Chapter 6 47

13 Chapter 6 Chemical Bonds 8. Circle the letter of the correct answer. The formula for sodium sulfide is Na 2 S. The sodium ion has a charge of 1. What must the charge on the sulfide ion be? a. 1 b. 0 c. 1 d. 2 Some Polyatomic Ions Name Formula Name Formula Ammonium NH 4 Acetate C 2 H 3 O 2 Hydroxide OH Peroxide O 2 2 Nitrate NO 3 Permanganate MnO 4 Sulfate SO 4 2 Hydrogen sulfate HSO 4 Carbonate CO 3 2 Hydrogen carbonate HCO 3 Phosphate PO 4 3 Hydrogen phosphate HPO Circle the letter that identifies the number of ammonium ions needed to form a compound with one phosphate ion. a. one b. two c. three d. four Describing Molecular Compounds (pages ) 10. What information is provided by the name and formula of a molecular compound? 11. Describe the general rule for naming molecular compounds. 12. Is the following sentence true or false? The formula for a molecular compound is written with the symbols for the elements in the same order as the elements appear in the name of the compound. 13. Circle the letter that identifies the method of naming the number of atoms in molecular compounds. a. prefix b. suffix c. number d. symbol 14. In the formula of a molecular compound, the number of atoms of an element in the molecule is represented by a(n). 48 Physical Science Guided Reading and Study Workbook Chapter 6

14 Chapter 6 Chemical Bonds Section 6.4 The Structure of Metals (pages ) This section discusses metallic bonds and the properties of metals. It also explains how the properties of an alloy are controlled. Reading Strategy (page 176) Relating Cause and Effect As you read, complete the concept map to relate the structure of metals to their properties. For more information on this Reading Strategy, see the Reading and Study Skills in the Skills and Reference Handbook at the end of your textbook. Mobile electrons produce 1. Circle the letter of the metal with the highest melting point. a. gold b. vanadium c. titanium d. tungsten 2. Is the following sentence true or false? The properties of a metal are related to bonds within the metal. Metallic Bonds (pages ) 3. Describe a metallic bond. 4. The cations in a metal form a lattice. What holds the lattice in place? 5. Is the following sentence true or false? The more valence electrons a metal has, the stronger its metallic bonds will be. Explaining Properties of Metals (page 177) 6. Some of the properties of metals can be explained by the of the electrons within a metal lattice. 7. Name two important properties of metals that can be explained by metallic bonding. a. b. Alloys (pages ) 8. Circle the letter of the percentage of gold in jewelry that is labeled 18-karat gold. a. 18 percent b. 50 percent c. 75 percent d. 100 percent Physical Science Guided Reading and Study Workbook Chapter 6 49

15 Chapter 6 Chemical Bonds 9. Is the following sentence true or false? When a metal such as copper is mixed with gold, the gold becomes softer. 10. Describe an alloy. 11. How do the hardness and strength of bronze compare to the hardness and strength of copper alone and tin alone? 12. Name two factors that scientists can vary to design alloys with specific properties. a. b. 13. Complete the following table. Comparing Bronze and Brass Alloy Component Metals Comparative Hardness Comparative Speed of Bronze and Brass of Weathering Bronze Copper, tin Weathers more slowly Brass Softer 14. When carbon is added to iron, the lattice becomes than a lattice that contains only iron. 15. Circle the letters of the elements that all types of steel contain. a. carbon b. chromium c. iron d. manganese 16. Circle the letters of each correct description of stainless steel. a. Stainless steel contains more carbon than chromium. b. Chromium forms an oxide that protects stainless steel from rusting. c. Stainless steel is more brittle than steels that contain more carbon. d. Stainless steel contains more than 3 percent carbon by mass. 17. Explain why pure aluminum is not the best material for the body of a plane. 18. What type of alloy is used to make airplane parts that need to be extremely lightweight? 50 Physical Science Guided Reading and Study Workbook Chapter 6

16 Chapter 7 Chemical Reactions Section 7.1 Describing Reactions (pages ) This section discusses the use of chemical equations and how to balance them. It also demonstrates the use of calculations in chemistry. Reading Strategy (page 192) Monitoring Your Understanding Preview the Key Concepts, topic headings, vocabulary, and figures in this section. List two things you expect to learn. After reading, state what you learned about each item you listed. For more information on this Reading Strategy, see the Reading and Study Skills in the Skills and Reference Handbook at the end of your textbook. What I Expect to Learn What I Learned Chemical Equations (pages ) 1. Is the following sentence true or false? The new substances formed as a result of a chemical reaction are called products. 2. Circle the letter of each sentence that is a correct interpretation of the chemical equation C O 2 h CO 2. a. Carbon and oxygen react and form carbon monoxide. b. Carbon and oxygen react and form carbon dioxide. c. Carbon dioxide yields carbon and oxygen. d. The reaction of carbon and oxygen yields carbon dioxide. 3. Is the following sentence true or false? The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. 4. Circle the letter of the correct answer. According to the equation C O 2 h CO 2, how many carbon atoms react with 14 molecules of oxygen to form 14 molecules of carbon dioxide? a. 1 b. 7 c. 14 d In the reaction represented by the equation C O 2 h CO 2, the mass of carbon dioxide produced equals. Physical Science Guided Reading and Study Workbook Chapter 7 53

17 Chapter 7 Chemical Reactions Balancing Equations (pages ) 6. Is the following sentence true or false? A chemical equation must be balanced in order to show that mass is conserved during a reaction. 7. Circle the letter of the name given to the numbers that appear before the formulas in a chemical equation. a. subscripts b. mass numbers c. atomic numbers d. coefficients 8. Is the following sentence true or false? Because the equation N 2 H 4 O 2 h N 2 H 2 O has two nitrogen atoms on each side, the equation is balanced. Counting With Moles (pages ) 9. Chemists use a counting unit called a(n) to measure amounts of a substance because chemical reactions often involve large numbers of small particles. 10. Circle the letter of the correct answer. If one carbon atom has an atomic mass of 12.0 amu and one oxygen atom has an atomic mass of 16.0 amu, what is the molar mass of carbon dioxide? a amu b amu c g d g 11. Circle the letter of the correct answer. To convert grams of carbon dioxide to moles of carbon dioxide, you must multiply by which conversion factor? a g CO 2 b. 1 mol CO 2 1 mol CO g CO 2 c g CO 2 d. 1 mol CO 2 1 mol CO g CO 2 Chemical Calculations (pages ) 12. Complete the table. Formation of Water Equation 2H 2 + O 2 h 2H 2 O Amount 2 mol 1 mol Molar Mass 2.0 g/mol 18.0 g/mol Mass (Moles Molar Mass) 32.0 g 36.0 g 13. Circle the letter of the correct answer. One mole of oxygen has a mass of 32 grams. What is the mass of four moles of oxygen? a. 128 g b. 144 g c. 128 amu d. 144 amu 54 Physical Science Guided Reading and Study Workbook Chapter 7

18 Chapter 7 Chemical Reactions Section 7.2 Types of Reactions (pages ) This section discusses how chemical reactions are classified into different types. Reading Strategy (page 199) Previewing Skim the section and begin a concept map like the one below that identifies types of reactions with a general form. As you read, add the general form of each type of reaction. For more information on this Reading Strategy, see the Reading and Study Skills in the Skills and Reference Handbook at the end of your textbook. Types of Reactions Synthesis Single Replacement A B h AB Classifying Reactions (pages ) 1. Name five general types of chemical reactions. 2. Circle the letter of each equation that represents a synthesis reaction. a. 2Na Cl 2 h 2NaCl b. 2NaCl h 2Na Cl 2 c. 2H 2 O h 2H 2 O 2 d. 2H 2 O 2 h 2H 2 O 3. Is the following sentence true or false? A decomposition reaction is the opposite of a synthesis reaction. 4. Write the equation for the decomposition of calcium carbonate into calcium oxide and carbon dioxide. 5. Circle the letter of the correct answer. Copper reacts with silver nitrate in a single-replacement reaction. What are the products of this reaction? a. copper(ii) nitride and silver oxide b. copper(ii) nitrate and silver c. copper(ii) oxide and silver nitrate d. copper, nitrogen, and silver oxide Physical Science Guided Reading and Study Workbook Chapter 7 55

19 Chapter 7 Chemical Reactions 6. What is a double-replacement reaction? 7. Complete the chart by filling in the general forms of the reactions shown. Single-Replacement Reaction General Forms Double-Replacement Reaction 8. Lead(II) nitrate reacts with potassium iodide to form lead(ii) iodide and potassium nitrate. Write the balanced equation for this double-replacement reaction. 9. Circle the letter of the correct answer. Calcium carbonate, CaCO 3, reacts with hydrochloric acid, HCl, in a double-replacement reaction. What are the products of this reaction? a. calcium chloride, CaCl 2, and carbonic acid, H 2 CO 3 b. calcium hydride, CaH 2, chlorine, Cl 2, and carbon dioxide, CO 2 c. calcium hydrogen carbonate, Ca(HCO 3 ) 2, and chlorine, Cl 2 d. calcium perchlorate, Ca(ClO 4 ) 2, and methane, CH Is the following sentence true or false? A combustion reaction is a reaction in which a substance reacts with carbon dioxide, often producing heat and light. 11. Methane, CH 4, burns in oxygen to form carbon dioxide and water. Write the balanced equation for this reaction. 12. Is the following sentence true or false? The reaction that forms water can be classified as either a synthesis reaction or a combustion reaction. Reactions as Electron Transfers (pages ) 13. What is an oxidation-reduction reaction? 14. Calcium reacts with oxygen to form calcium oxide. Which reactant is oxidized in this reaction? 15. Is the following sentence true or false? When calcium reacts with oxygen, each calcium atom gains two electrons and becomes a calcium ion with a charge of Is the following sentence true or false? Oxygen must be present in order for an oxidation-reduction reaction to take place. 17. The process in which an element gains electrons during a chemical reaction is called. 56 Physical Science Guided Reading and Study Workbook Chapter 7

20 Chapter 7 Chemical Reactions Section 7.3 Energy Changes in Reactions (pages ) This section discusses how chemical bonds and energy relate to chemical reactions. Reading Strategy (page 206) Comparing and Contrasting As you read, complete the Venn diagram below to show the differences between exothermic and endothermic reactions. For more information on this Reading Strategy, see the Reading and Study Skills in the Skills and Reference Handbook at the end of your textbook. Exothermic Reaction Endothermic Reaction Chemical bonds are broken and formed. Chemical Bonds and Energy (pages ) 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. What role does the spark from the igniter play in the reaction that takes place when propane is burned in a gas grill? 5. Is the following sentence true or false? The heat and light given off by a propane stove result from the formation of new chemical bonds. 6. The combustion of one molecule of propane (C 3 H 8 ) results in the formation of C O double bonds and O H single bonds. Physical Science Guided Reading and Study Workbook Chapter 7 57

21 Chapter 7 Chemical Reactions Exothermic and Endothermic Reactions (pages ) 7. During a chemical reaction, energy is either released or. 8. Is the following sentence true or false? Physical and chemical changes can be either exothermic or endothermic changes. 9. What is an exothermic reaction? 10. 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. Reaction Energy Exothermic Chemical Energy Reactants Energy released by reaction Products Reaction Progress 11. Circle the letter of each sentence that is correct for the graph above. 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. 12. In an exothermic reaction, the difference between the chemical energy of the reactants and the chemical energy of the products equals 13. Where does the energy term appear in the equation for an endothermic reaction? Conservation of Energy (page 209) 14. In an endothermic reaction, heat from the surroundings plus the chemical energy of the reactants is converted into the.. 58 Physical Science Guided Reading and Study Workbook Chapter 7

22 Chapter 7 Chemical Reactions Section 7.4 Reaction Rates (pages ) This section discusses the factors that affect reaction rates. Reading Strategy (page 212) Building Vocabulary As you read, complete the web diagram below with key terms from this section. For more information on this Reading Strategy, see the Reading and Study Skills in the Skills and Reference Handbook at the end of your textbook. Factors affecting reaction rates Reactions Over Time (page 212) 1. Any change that happens over time can be expressed as a(n). 2. What is a reaction rate? Factors Affecting Reaction Rates (pages ) 3. Is the following sentence true or false? One way to observe the rate of a reaction is to observe how fast products are being formed. 4. Is the following sentence true or false? The rate of any reaction is a constant that does not change when the reaction conditions change. 5. Generally, an increase in temperature will the reaction rate. 6. Is the following sentence true or false? Storing milk in a refrigerator stops the reactions that would cause the milk to spoil. 7. How does an increase in surface area affect the exposure of reactants to one another? Physical Science Guided Reading and Study Workbook Chapter 7 59

23 Chapter 7 Chemical Reactions 8. Why does increasing the surface area of a reactant tend to increase the reaction rate? 9. Stirring the reactants in a reaction mixture will generally the reaction rate. 10. Is the following sentence true or false? Increasing the concentration of the reactants will generally slow down a chemical reaction. 11. Is the following sentence true or false? A piece of material dipped in a concentrated dye solution will change color more quickly than in a dilute dye solution. 12. Why does an increase in pressure speed up the rate of a reaction involving gases? 13. What is a catalyst? 14. Circle the letters of the sentences that correctly identify why chemists use catalysts. a. to speed up a reaction b. to enable a reaction to occur at a higher temperature c. to slow down a reaction d. to enable a reaction to occur at a lower temperature 15. Is the following sentence true or false? Because a catalyst is quickly consumed in a reaction, it must be added to the reaction mixture over and over again to keep the reaction going. 16. Identify where the catalyst V 2 O 5 should go in the formula shown and write it in the correct location. 2SO 2 O 2 h 2SO Circle the letter of the correct answer. In the reaction represented Pt by the equation 2H 2 O 2 h 2H 2 O + O 2, which substance acts as a catalyst? a. H 2 O 2 b. Pt c. H 2 O d. O One way that a catalyst can lower the energy barrier of a reaction is by providing a surface on which the can come together. 60 Physical Science Guided Reading and Study Workbook Chapter 7

24 Chapter 7 Chemical Reactions Section 7.5 Equilibrium (pages ) This section explains physical and chemical equilibria, and describes the factors that affect chemical equilibrium. Reading Strategy (page 216) Outlining As you read, make an outline of the most important ideas from this section. For more information on this Reading Strategy, see the Reading and Study Skills in the Skills and Reference Handbook at the end of your textbook. I. Equilibrium A. Types of Equilibria B. 1. Temperature 2. Pressure 3. Types of Equilibria (pages ) 1. What is equilibrium? 2. Circle the letter of the correct answer. In the system described by the equation H 2 O(l) m H 2 O(g), at room temperature, which of the following two physical changes are in equilibrium? a. sublimation and condensation b. evaporation and melting c. sublimation and deposition d. evaporation and condensation 3. What happens when a physical change does not go to completion? 4. What does the single arrow imply about the reaction described in the following equation? CH 4 (g) + 2O 2 (g) h CO 2 (g) + 2H 2 O(g) Physical Science Guided Reading and Study Workbook Chapter 7 61

25 Chapter 7 Chemical Reactions 5. Circle the letter of the correct answer. In the system described by the equation 2SO 2 (g) O 2 (g) m 2SO 3 (g), what two reaction types are in equilibrium? a. synthesis and decomposition b. single replacement and decomposition c. synthesis and combustion d. synthesis and double replacement 6. What happens when a chemical change does not go to completion? Factors Affecting Chemical Equilibrium (pages ) 7. Is the following sentence true or false? A change in reaction conditions does not affect a chemical equilibrium. 8. Circle the letter of each correct answer. The synthesis of ammonia is described by the equation N 2 (g) 3H 2 (g) m 2NH 3 (g) heat. Which reaction is favored when the temperature is lowered? a. the forward reaction b. the reverse reaction c. the reaction that removes heat from the system d. the reaction that adds heat to the system 9. Circle the letter of each correct answer. During the synthesis of ammonia, which reaction is favored when hydrogen is added to the system? a. the forward reaction b. the reverse reaction c. the reaction that removes hydrogen from the system d. the reaction that adds hydrogen to the system 10. According to Le Châtelier s principle, how does lowering the concentration of a reaction product affect a chemical equilibrium? 11. Use the equation C(s) + H 2 O(g) + heat m CO(g) + H 2 (g) to complete the table below. An Example of Le Châtelier s Principle An increase in Shifts the equilibrium so as to Favoring the Pressure Concentration of H 2 Remove heat Produce fewer gas molecules Forward reaction Reverse reaction 62 Physical Science Guided Reading and Study Workbook Chapter 7