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CHAPTER 11 CHEMICAL REACTIONS 1 Do Now Date: __________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ Do Now Date: __________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ Do Now Date: __________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ 2 Do Now Date: __________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ Do Now Date: __________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ Do Now Date: __________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ 3 INTRODUCTION Chemical changes are a result of chemical reactions. All chemical reactions involve a change in substances and a change in energy. Neither matter nor energy is created or destroyed in a chemical reaction---only changed. There are so many chemical reactions that it is helpful to classify them into types. These will be the topic of this chapter. READING ACTIVITY Pages:320-329 Chapter 11: Chemical Reactions Describing Chemical Reactions Section: 11.1 Key Concepts: By the end of this section you will be able to: 1. write a Word Equation. 2. write a Skeleton Equation 3. write a balanced chemical equation. VOCABULARY 1) Chemical equation - ___________________ ______________________________________ 4 2) Skeleton Equation - _____________________ ________________________________________________ ________________________________________________ 3) Catalyst - __________________________________ ________________________________________________ ________________________________________________ ________________________________________________ 4) Coefficients - ________________________________ ________________________________________________________________________ ________________________________________________________________________ 5) Balanced equation - _________________________ ________________________________________________ ________________________________________________ ________________ A- Writing Chemical Equations Notes: 1 . In a chemical reaction one or more substances (_________ ) change into one or more new substances (____________ ) . 5 2. A quick shorthand method known as a ________ _________ is used to convey as much information as possible about what happened in the chemical reaction. 3. Word Equations a. __________________ PRODUCTS ----b. The arrow in the equation means _____, _________ or ______________________. c. When reacting Iron and oxygen to produce rust (iron(III)oxide) you would write _____________________________________ d. To write a word equation:' i.Write the names of the ____________to the left of the arrows. ii. Write the names of the the right of the arrow. 6 to e. The reaction of hydrogen peroxide decomposing into oxygen and hydrogen would be written as follows: Hydrogen Peroxide water + oxygen. f. In the above reaction are produced. This lets us know a gas is being given off. g. When natural gas (methane) is burned on your stove or Bunsen burner the reaction is written as follows: _________________________________________ Checkpoint: What does the arrow () in a word equation mean? _____________________________________________ _____________________________________________ _____________________________________________ 7 4. Chemical Equations a. A chemical equation is a . (on the left) are b.The connected to the right) by an (on the . c. Write the chemical equation for rusting below. _______________________________________ d. Equations that show just the formulas of the reactants and products are called ______________ ________________ . e. The first step in writing a chemical equation is to write a skeleton equation. i. Write the formulas _______________ _ ____________. 8 . ii. To add more information to the equation you can indicate the ________________ of substances by putting a __________________ 1. (s) 2. (g) 3.(1) 4. (aq) Add the physical states to the equation: Practice Problems: from pg 324 1 .Write a sentence that describes this chemical reaction: Na((s) + H2O (l) NaOH (aq) + H2 (g) 2. Sulfur burns in oxygen to form sulfur dioxide. Write a skeleton equation for this chemical reaction. Include appropriate symbols from Table 11.1. ________________________________________ Things I don't understand: 9 B- Balancing Chemical Equations Notes: 1. Using the equation for the synthesis of water the parts of the equation are shown below. 4. 3.22 2H2 + COEFFICIENTS O2 CHEMICAL FORMULA 2H2O SUBSCRIPT Coefficient- _____________________________________ _________________________________________________ _______________________ ______________________ _ Chemical formula- _______________________________ ________________________________________ Subscript- ___________________________________ ___________________________________ ___________ _ In a ________________________________, there are the same numbers at each atom on both sides of the ____________sign. For example:' 10 S(S) + 02 (g) S02 (g) S=1 0=2 S=1 0=2 In the above equation, there is ______ sulfur atom on the left of the arrow and sulfur atom on the right of the arrow. Also there are 2 __________ atoms on the left side and 2 oxygen atoms on the right. The amounts of oxygen and sulfur are __ on both sides of the arrow. In the equation below the elements are not equal on both sides. Let’s count them up to see how many we have. H 2 + 02 H 2 0 H= _____ O= _____ H= ____ O= ____ There are ___ hydrogen on the left and ___ on the right of the arrow. There are ___ oxygen atoms on the right of the arrow and only _______on the left. We need to 11 6. 5. make them equal. To do this I can only add _________ (numbers in front ) to the equation. I need___ 0 on the right of the arrow because I have 2 on the left of the arrow. I can place a coefficient of 2 in front of the ____ on the right of the arrow. I then multiply the coefficient of 2 by the subscript of 2 in the hydrogen. This gives me___hydrogen. If I multiply the coefficient 2 by the subscript of the 0, which is ___ ,I have a total of 2 oxygen on both sides. They are equal but now my hydrogen are not equal. H 2 + 02 2 H 20 H= _____ O= __2___ H= 2 O= __2__ I need to place a 2 in front of the H2 on the left of the arrow. This will give me 4 hydrogen. Now everything on the left of the arrow is equal to everything on the right of the arrow. 2H2 + 02 2 H20 H= _____ O= __2___ H= 4 O= __2__ 12 The equation is balanced ! Rules for Writing and Balancing Equations 1. Determine the correct formulas and physical states for all the ____________ and ________________. 2. Write the _____________________ with the formulas for the reactants on the left and formulas for the products on the right of a yield sign. If 2 or more reactants or products are involved, separate their formulas with plus signs. 3.Count the number of each element in the reactants and products. Count a polyatomic ion as a single unit if it appears unchanged on both sides of the equation. 4. Balance the number of atoms of the elements on the two sides of the equation by placing _____________ in front of the formulas. When no coefficients written, it is assumed to be 1. Begin by balancing elements that appear only once on each side of the equation. Never balance an equation by changing the _________ _ in a chemical formula. Each substance has only one correct formula. S. Check each atom or polyatomic ion to be sure the equation is . 6. Make sure all the coefficients are in the possible ratio. 13 Checkpoint: What is the Law of Conservation of Mass? (Pg.325)_ Practice Problems (Pg 327) 3. Directions: Balance each equation. 'Place the coefficient on the line to the left of the formula. Some lines may not be filled in.. a. __ AgN03 + __ H2S __ Ag2S + __ HN03 4. Directions: Rewrite these word equations as balanced chemical equations. a. hydrogen + sulfur hydrogen sulfide b. iron (III) chloride + calcium hydroxide iron (III) hydroxide + calcium chloride 14 11 . 1 Section Assessment Questions: (pg 329) 7. How do you write a word equation? 8.How do you write a skeleton equation? 9. Describe the steps in writing a balanced chemical equation. 1 O. Write the skeleton equations for these reactions. a. heating copper(lI) sulfide in the presence of diatomic oxygen produces pure copper and sulfur dioxide gas. b. When heated, baking soda (sodium hydrogen carbonate)decomposes to form the products sodium carbonate, carbon dioxide and water. 15 Write and balance equations for the following reactions. a. Iron metal and chlorine gas react to form solid iron (III) chloride. b. solid aluminum carbonate decomposes to form solid aluminum oxide and carbon dioxide gas. c. Solid magnesium reacts with aqueous silver nitrate to form solid silver and aqueous magnesium nitrate. 2. Balance the following equations. a- S02 + b. __Fe203 + 02 H2 S03 Fe + H20 c. ___ P + ____ 02 ____ P4010 d. _____ Al+ ____N2 _____ AlN Things I don't understand: ____________________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ 16 EXERCISE 1: SKELETON EQUA TIONS DIRECTIONS: Write the chemical equation for each of the following skeleton equations. 1. hydrogen reacts with oxygen to produce water 2. potassium chloride reacts with aluminum to produce potassium and aluminum chloride 3. calcium reacts with sodium hydroxide to produce sodium and calcium hydroxide 4. calcium carbonate decomposes yielding calcium oxide and carbon dioxide 5. Hydrogen chloride reacts with sodium hydroxide to produce water and sodium chloride 6. Copper reacts with hydrogen chloride to produce copper (II)chloride and hydrogen gas 7. methane gas (CH4) burns in oxygen to produce carbon dioxide and water 8. chlorine and sodium hydroxide react to produce sodium chloride and sodium hypochlorite and water 9. calcium reacts with water to produce calcium hydroxide and water 10. calcium sulfate and sodium carbonate react to produce calcium carbonate and sodium sulfate 17 Exercise 2: Balancing Equations Directions: Balance the following equations. After the equation is balanced, add the coejJiecients and place the total on the line to the right. Blank lines count as 1. TOTAL: _____________ 2. TOTAL: _ 3. TOTAL: 4. HCl+ NaOH NaCl+ H 20 TOTAL: 5. KOH + _HBr KBr + Mg + Cl2 MgCI2 TOTAL: _ 18 _ H20 TOTAL: 6. _ _ TYPES OF CHEMICAL REACTIONS Section: 11.2 Key Concepts: By the end of this section you will be able to: 1 . identify the five general types of reactions 2. Predict products for the five general types of reactions. VOCABULARY Combination Reaction- ________________________ ___________________________________________ ___________________________________________ EXAMPLE: Decomposition Reaction - EXAMPLE: ________________________________________ _ 19 Single-replacement Reaction - EXAMPLE: Double-replacement Reaction- EXAMPLE: Combustion Reaction - EXAMPLE: Activity Series - 20 Checkpoint: What are the products of the combustion of a hydrocarbon?(pg.336) _____________________________________ SECTION 11.2 TYPES OF CHEMICAL REACTIONS (pages 330-339) This section explains how to identify a reaction as a combination, decomposition, single-replacement, double-replacement, or combustion reaction. It also describes how to predict the products of each type of reaction. Classifying Reactions (page 330) 1.There are reactions. ____ general types of chemical 2. Complete the diagram of a combination reaction. Which characteristic of this type of reaction is shown in the diagram? + 2Mg(s) Magnesium 2MgO(s) + Magnesium oxide 3. Is the following sentence true or false? The product of a combination reaction is always a molecular compound. _ 4. Circle the letter of each set of reactants that can produce more than one product. a. two nonmetals c. a transition metal and a nonmetal b. a Group A metal and a nonmetal d. two metals 5. Look at Figure 11.6 on page 332. Which characteristics of a decomposition reaction are shown in the diagram? 21 Name ________________________ _ Date ________________ _ Class _________________ CHAPTER 11, Chemical Reactions (continued) 6.Rapid decomposition reactions can cause of the formation of gaseous products and heat. as a result 7.Most decomposition reactions require the addition of _______________ _ in the form of heat, light, or electricity. 8.Complete the diagram of a single replacement reaction. Which characteristics of this type of reaction are shown in the diagram? + 2KOH(aq) Potassium hydroxide 2K(s) Potassium + H2(g) Hydrogen 9. Using Table 11.2 on page 333, state whether the following combinations will produce a reaction or no reaction. a.Ag(s) + HCl(aq) _____________ b.Cu(s) + AgN03(aq) ________________ 10. Look at Figure 11.8 on page 335. Which characteristics of a doublereplacement reaction are shown in the diagram? 11. When solutions of ionic compounds are mixed, what three circumstances may indicate that a double-replacement reaction has occurred? a. ___________________________________________________________________ _ b. ____________________________________________________ _ c. ________________________________________________________ 12. Look at the diagram of a combustion reaction in Figure 11.9 on page 336. Which characteristics of this type of reaction are shown in the diagram? 22 2 0 Name __________________________ Date _________________ Class ________________ _ 13. Is the following sentence true or false? Hydrocarbons, compounds of hydrogen and carbon, are often the reactants in combustion reactions. 14. Circle the letter of each compound that can be produced by combustion reactions. a. oxygen b. carbon dioxide c.water d.glucose 23 Predicting the Products of a Chemical Reaction (pages 337-339) 15. Classify the reaction in each of the following equations. a.BaClz(aq) + KZCr04(aq) ~ BaCr04(s) + 2KCI (aq) _____________ _____ b.Si(s) + 2Clz(g) ~ SiCI4(l) __________________ _ c. 2CsHs(l) + 150z(g) ~ 6HzO(l) + 12COz(g) ____ _______________ _ 16. Use Figure 11.10 on page 339. The equation for the combustion of pentane is C5H1Z + 80z ~ 5COz + 6HzO. What numbers in this equation are represented by x and y in the general equation 24 Types of Reactions Directions: State whether each of the following equations represents a combination (e), decomposition (0), single replacement (SR), or double replacement (OR) reaction or combustion (CR) reaction. 1. CO2 C + O2 2.NaCI + AgN03 NaN03 + AgCI 3. S + CI2 SCI2 4. BaCI2 + 2 NaOH 2NaCI + Ba(OH)2 5.Zn + CuS04 ZnS04+ Cu 6. CH4 C + 2H2 7. Mg + 2HCI MgCI2 + H2 8. 2KI + Br2 9. 2NaF 2KBr + 12 2Na + F2 10. Si + O2 Si02 11. 2Nal + Pb(N03)2 2NaN03 + Pbl2 12. Li3 P04 3 Li + P + 202 13. CS2 + 2F2 CF4 + 2S 25 SECTION 11.3 Reactions in Aqueous Solution Key Concepts: By the end of this section you will be able to: 1 - write and describe a net ionic equation. 2 - Predict the formation of a precipitate in a double-replacement reaction. VOCABULARY 1) Net Ionic Equation - ___________________ ______________________________________ 2) Complete Ionic Equation - _____________________ ________________________________________________ ________________________________________________ 3) spectator ion ________________________________ ________________________________________________ ________________________________________________ ________________________________________________ 26 SECTION 11.3 REACTIONS IN AQUEOUS SOLUTION (pages 342-344) This section explains how to write and balance net ionic equations. It also describes the use of solubility rules to predict the formation of precipitates in double-replacement reactions. ~ Net Ionic Equations (pages 342-343) 1.Many important chemical reactions take place in _____ 2.An equation that shows dissolved ionic compounds as their free ions is called a(n) 3.Is the following sentence true or false? A spectator ion is not directly involved in a reaction. 4.What is a net ionic equation? 27 5. Circle the letter of each sentence that is true about ionic equations. a. A complete ionic equation shows only the ions involved in the reaction. b. Spectator ions are left out of a net ionic equation. c.Atoms do not need to be balanced in an ionic equation. d. Ionic charges must be balanced in a net ionic equation. 6.Write the balanced net ionic equation for this reaction: Pb(N03Maq) + Kl(aq) ~ PbI2(s) + KN03(aq). Show your work. ~ Predicting the Formation of a Precipitate (page 344) 7.What determines whether a precipitate forms when two solutions of ionic compounds are mixed? 8. Use Table 11.3 on page 344 to predict whether the following compounds are soluble or insoluble. a. Fe(OH)3 b. NaOH c.Ca(Cl03)2 _____________ _ d. HgS04 28 Reaction Prediction Name: ________________ Directions: Predict the products and write balanced chemical equations. + ____ Na 1. ____ BaCI2 2. ____HCI 3. ____AgN03 + ____Na3P04 4. ____NaOH + ____Fe(N03)3 5. ___02 + ____Na 6. 7. ____NiS04 + ____ KOH ____Fe + ____ AgCI Directions: Write chemical equations for the following predicting the products of the reactions. Don't forget to BALANCE! 1. silver nitrate+ potassium iodide 2. Copper (II) sulfate + sodium 3. Cobalt chloride + sodium hydroxide 4. Nickel (II) chloride 5. Copper + sulfurous acid (H2S03 ) 6. Magnesium oxide + water 7. Barium chloride (heated) 8. Manganese (IV) chloride + oxygen gas 9. Ammonium sulfate + lead (II) 10. Sulfur trioxide + water ~ 29 Name _______________________ _ Date ________________ _ Class ________________ _ PRACTICE PROBLEMS 2. Sulfur burns in oxygen to form sulfur dioxide. Write a skeleton equation for this chemical reaction. Include appropriate symbols from table 11.1. Analyze Step 1. Identify the relevant concepts. Write the formula for each reactant and each product. Include the common STP state of each substance. Reactants Products Solve Step 2. Write the skeleton equation using + between reactants on the left hand side and to separate reactants from products: Do you remember? What are the indications of chemical reactions? _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ 30 Here are some practice problems.. 1. __NaCl + __BeF2 --> __NaF + __BeCl2 2. __FeCl3 + __Be3(PO4)2 --> __BeCl2 + __FePO4 3. __AgNO3 + __LiOH --> __AgOH + __LiNO3 4. __CH4 + __O2 --> __CO2 + __H2O 5. __Mg + __Mn2O3 --> __MgO + __Mn 31 Name _______________________ _ Date _______________ _ Class _______________ _ REACTIONS CHEMICAL Vocabulary Review Each clue describes a vocabulary term. Read the clues and write the letters of each term on the lines provided. 1. Clue: the complete reaction of a hydrocarbon with oxygen to produce carbon dioxide and water. ------0--2. Clue: a single compound is broken down into two or more products. -0---0------3. Clue: the equation indicating only those particles that actually take part in a chemical reaction in an aqueous solution. 0--0- 4. Clue: a substance that speeds up the rate of a chemical reaction. -0-----5. Clue: the elements or compounds on the left side of a chemical equation. 0-------6. Clue: ions that do not participate in an aqueous chemical reaction. -0------7. Clue: reaction in which atoms of one element replace the atoms of a second, less reactive, element in a compound. ----------0 8. Clue: a chemical equation that is consistent with the law of conservation of mass. ------09. Clue: numbers placed in front of chemical symbols or formulas in a chemical reaction. 0----------Write the letters found inside the circles on the lines below. Then unscramble them to find the term used to describe an insoluble salt. Scrambled letters: 32 Name ________________________ _ Date _________________ _ Class _______________ _ CHEMICAL REACTIONS Practice Problems In your notebook, solve the following problems. Use the 3-step problem-solving approach you learned in Chapter 1. SECTION 11.1 DESCRIBING CHEMICAL REACTIONS 1. Write the skeleton equation for the reaction between hydrogen and oxygen that produces water. 2. Write the skeleton equation for the reaction that produces iron (II) sulfide from iron and sulfur. 3. Write the skeleton equation representing the heating of magnesium carbonate to produce solid magnesium oxide and carbon dioxide gas. 4. Write a balanced equation for the production of HCI gas from its elements. 5. Write a sentence that completely describes the chemical reaction represented by this balanced equation. 2HCl(aq) + CaC03(s) CO2(g) + CaCl2(aq) + H 2O(l) 6. Write the word equation for the following equation. Write a sentence fully describing the reaction. Is the equation correctly balanced? Explain. 2Ag(s) + S(s) Ag 2S(s) 7. Write a balanced equation representing the formation of aqueous sulfuric acid from water and sulfur trioxide gas. 8. Write a balanced equation from this word equation. aqueous silver nitrate + copper metal ~ silver metal + aqueous copper nitrate 9. Write a balanced equation for the following word equation. phosphorus + oxygen ~ tetraphosphorous decoxide SECTION 11.2 TYPES OF CHEMICAL REACTIONS 1. Write a balanced equation representing the reaction of magnesium with oxygen gas to produce magnesium oxide. 2. Write the balanced equation for the reaction that occurs between aluminum and fluorine. 3. Write the balanced equation for the production of oxygen gas and potassium chloride from the decomposition of potassium chlorate. 4. Write the balanced equation for the reaction between hydrochloric acid and calcium metal. The products are hydrogen gas and calcium chloride. 5. Write the balanced equation for the combustion of propane (C3Ha) to produce carbon dioxide and water vapor. 6. Write the balanced equation for the reaction between iron (III) chloride and sodium hydroxide. The products are iron (III) hydroxide and sodium chloride. 33 Name ________________________ _ Date ________________ _ Class ________________ _ 7. Classify each of the reactions in problems 1-6 as to type. 8. Use the activity series of metals (Table 11.2) and your knowledge of the relative reactivity of the halogens to predict whether the following reactions will occur. Write balanced equations for those reactions that do occur. a. Br2(s) + NaCl(aq) b. Ca(s) + Mg(N03)2 (aq) c. K(s) + H2S04(aq) d. Zn(s) + NaOH(aq) SECTION 11.3 REACTIONS IN AQUEOUS SOLUTION 1. Write the net ionic equation for the reaction between aqueous barium nitrate, Ba(N03lz. and sodium sulfate, NaZS04. 2. Magnesium reacts with HCI to form hydrogen and magnesium chloride. Write the balanced net ionic equation for this reaction. 3. The double-replacement reaction below results in the formation of the precipitate lead chloride. Balance the equation and write the net ionic equation. Pb(N03)2(aq) + NH4Cl(aq) ~ PbCl2(s) + NH4N03(aq) 4. Identify the precipitate formed when solutions of the following ionic compounds are mixed. If no precipitate is formed, write no precipitate. a. Zn(N03)2 + SnCl2 b. KCI + AgN03 c. Cu(N03)2 + Na2S ~ d. Al2(S04)3 + 3Mg(OH)2 34 2 7 2 C or e T ea ch in g R es ou rc es NAME: -----------------Predicting Reaction Products & Balancing Chemical Equations Reaction Type 1. Reactants C3HS + O2 2. C7H16 + O2 3. C2H2 + O2 4. C4H1O + O2 Products 5. C6H6 + O2 6. Mg + N2 7. Na + 82 8. Mg + O2 9. AI + O2 10. K + P 11. H3P04 H4P207 + H2O 12. HgO Hg + O2 35 13. H202 H2O + O2 + O2 14. KCI03 KCI 15. AU203 Au 16. Zn + HCI 17. AI + FeO 18. Al + HCI 19. Ca + AICh 20. Fe2(S04)3 + KOH 21. AI2(S04)3 + Ca(OH)2 22. FeCI3 + NH40H 23. BaCI2 + Ah(S04)3 24. SrBr2 + (NH4)2C03 25. Hg(OH)2 + H3P04 36 + O2