Presentation on theme: "Chapter 9 Chemical Reactions. National Standards for Chapter 9 UCP.3 – Change, constancy, and measurement UCP.5 – Form and function A.1 –Abilities necessary."— Presentation transcript:
Chapter 9 Chemical Reactions
National Standards for Chapter 9 UCP.3 – Change, constancy, and measurement UCP.5 – Form and function A.1 –Abilities necessary to do scientific inquiry A.2 – Understandings about scientific inquiry B-2 – Structure and properties of matter B-3 – Chemical reactions B-6 – Interactions of energy and matter
Vocabulary/Study Guide Define each term using the Glossary Either write on the handout, or use your own paper This is due on Test Day (tentatively, Thursday, March 6)
Section 1: Reactions and Equations National Standards: UCP.3 – Change, constancy, and measurement UCP.5 – Form and function A.1 –Abilities necessary to do scientific inquiry B-2 – Structure and properties of matter B-3 – Chemical reactions B-6 – Interactions of energy and matter
Objectives – Section 1 Recognize evidence of chemical change. Represent chemical reactions with equations. Balance chemical equations. REVIEW VOCABULARY: chemical change: a process involving one or more substances changing into a new substance
New Vocabulary chemical reaction reactant product chemical equation coefficient Chemical reactions are represented by balanced chemical equations.
Launch Lab Title: How do you know when a chemical change has occurred? (page 280)
Math Skills Transparency 11
Chemical Reactions The process by which one or more substances are rearranged to form different substances is called a chemical reaction.
Chemical Reactions Evidence that a chemical reaction may have occurred: – Change in temperature – Change in color – Odor – Gas bubbles – Appearance of a solid (precipitate)
Representing Chemical Reactions Chemists use statements called equations to represent chemical reactions. Reactants are the starting substances. Products are the substances formed in the reaction. This table summarizes the symbols used in chemical equations.
Representing Chemical Reactions In word equations, aluminum(s) + bromine(l) aluminum bromide(s) reads as aluminum and bromine react to produce aluminum bromide. Skeleton equations use symbols and formulas to represent the reactants and products. Al(s) + Br(l) AlBr 3 (s) Both word and skeleton equations lack information about how many atoms are involved in the reaction.
Representing Chemical Reactions A chemical equation is a statement that uses chemical formulas to show the identities and relative amounts of the substances involved in a chemical reaction.
Representing Chemical Reactions Practice Problems #1-3, page 284
Balancing Chemical Equations This figure shows the balanced equation for the reaction between aluminum and bromine.
Balancing Chemical Equations A coefficient in a chemical equation is the number written in front of a reactant or product, describing the lowest whole-number ratio of the amounts of all the reactants and products.
Balancing Chemical Equations
Transparency 29: Parts of a Balanced Chemical Equation
Representing Chemical Reactions Practice Problems #4-6, page 287
Transparency 30: Balancing Chemical Equations
Balancing Chemical Equations The most fundamental law in chemistry is the law of conservation of mass. Balanced equations show this law.
Balancing Chemical Equations
Homework, Section 1 SECTION 1 REVIEW, Page 288 Questions #7-13 Answer with complete sentences Due tomorrow
Section 2: Classifying Chemical Reactions National Standards: UCP.3 – Change, constancy, and measurement UCP.5 – Form and function A.1 –Abilities necessary to do scientific inquiry B-2 – Structure and properties of matter B-3 – Chemical reactions
Objectives – Section 2 Classify chemical reactions. Identify the characteristics of different classes of chemical reactions. Review Vocabulary: metal: an element that is a solid at room temperature, a good conductor of heat and electricity, and is generally shiny
New Vocabulary synthesis reaction combustion reaction decomposition reaction single-replacement reaction double-replacement reaction precipitate There are four types of chemical reactions: synthesis, combustion, decomposition, and replacement reactions.
Types of Chemical Reactions Chemists classify reactions in order to organize the many types.
Synthesis Reactions A synthesis reaction is a reaction in which two or more substances react to produce a single product. When two elements react, the reaction is always a synthesis reaction.
Combustion Reactions In a combustion reaction, oxygen combines with a substance and releases energy in the form of heat and light. Heated hydrogen reacts with oxygen to produce heat and water in a combustion reaction. This is also a synthesis reaction.
Combustion Reactions Practice Problems #14-17, page 291
Decomposition Reactions A decomposition reaction is one in which a single compound breaks down into two or more elements or new compounds. Decomposition reactions often require an energy source, such as heat, light, or electricity, to occur.
Decomposition Reactions Practice Problems #18-20, page 292
Replacement Reactions A reaction in which the atoms of one element replace the atoms of another element in a compound is called a single replacement reaction. A + BX AX + B
Replacement Reactions A metal will not always replace a metal in a compound dissolved in water because of differing reactivities. An activity series can be used to predict if reactions will occur.
Replacement Reactions Halogens frequently replace other halogens in replacement reactions. Halogens also have different reactivities and do not always replace each other.
Replacement Reactions Practice Problems #21-24, page 295
Replacement Reactions Double replacement reactions occur when ions exchange between two compounds. This figure shows a generic double replacement equation.
Replacement Reactions The solid product produced during a chemical reaction in a solution is called a precipitate. All double replacement reactions produce either water, a precipitate, or a gas.
Replacement Reactions This table shows the steps to write double replacement reactions.
Replacement Reactions Practice Problems #25-28, page 297
Replacement Reactions This table summarizes different ways to predict the products of a chemical reaction.
Transparency 32: Summary of Reaction Types
Lab: Develop an Activity Series, page 310
Lab: Single-Replacement Reactions
Lab: Double-Replacement Reactions
Homework, Section 2 SECTION 2 REVIEW, Page 298 Questions #29-34 Answer with complete sentences Due tomorrow
Section 3: Reactions in Aqueous Solutions National Standards: UCP.3 – Change, constancy, and measurement UCP.5 – Form and function A.1 –Abilities necessary to do scientific inquiry A.2 – Understandings about scientific inquiry B-2 – Structure and properties of matter B-3 – Chemical reactions B-6 – Interactions of energy and matter
Objectives – Section 3 Describe aqueous solutions. Write complete ionic and net ionic equations for chemical reactions in aqueous solutions. Predict whether reactions in aqueous solutions will produce a precipitate, water, or a gas. Review Vocabulary: solution: a uniform mixture that might contain solids, liquids, or gases
New Vocabulary aqueous solution solute solvent complete ionic equation spectator ion net ionic equation Double-replacement reactions occur between substances in aqueous solutions and produce precipitates, water, or gases.
Aqueous Solutions An aqueous solution contains one or more dissolved substances (called solutes) in water. The solvent is the most plentiful substance in a solution.
Aqueous Solutions Water is always the solvent in an aqueous solution. There are many possible solutessugar and alcohol are molecular compounds that exist as molecules in aqueous solutions. Compounds that produce hydrogen ions in aqueous solutions are acids.
Aqueous Solutions Ionic compounds can also be solutes in aqueous solutions. When ionic compounds dissolve in water, their ions separate in a process called dissociation.
Type of Reactions in Aqueous Solutions When two solutions that contain ions as solutes are combined, the ions might react. If they react, it is always a double replacement reaction. Three products can form: precipitates, water, or gases.
Type of Reactions in Aqueous Solutions Title:Observe a Precipitate-Forming Reaction, page 301
Type of Reactions in Aqueous Solutions Aqueous solutions of sodium hydroxide and copper(II) chloride react to form the precipitate copper(II) hydroxide. 2NaOH(aq) + CuCl 2 (aq) 2NaCl(aq) + Cu(OH) 2 (s) Ionic equations that show all of the particles in a solution as they actually exist are called complete ionic equations. 2Na + (aq) + 2OH – (aq) + Cu 2+ (aq)+ 2Cl – (aq) 2Na + (aq) + 2Cl – (aq) + Cu(OH) 2 (s)
Type of Reactions in Aqueous Solutions Ions that do not participate in a reaction are called spectator ions and are not usually written in ionic equations. Formulas that include only the particles that participate in reactions are called net ionic equations. 2OH – (aq) + Cu 2+ (aq) Cu(OH) 2 (s)
Type of Reactions in Aqueous Solutions Practice Problems #35-39, page 302
Type of Reactions in Aqueous Solutions Some reactions produce more water molecules. No evidence of a chemical reaction is observable. HBr(aq) + NaOH(aq) H 2 O(l) + NaBr(aq) Without spectator ions H + (aq) + OH – (aq) H 2 O(l).
Type of Reactions in Aqueous Solutions Practice Problems #40-44, page 304
Type of Reactions in Aqueous Solutions Gases that are commonly produced are carbon dioxide, hydrogen cyanide, and hydrogen sulfide. 2HI(aq) + Li 2 S(aq) H 2 S(g) + 2LiI(aq)
Type of Reactions in Aqueous Solutions Another example is mixing vinegar and baking soda, which produces carbon dioxide gas. HCl(aq) + NaHCO 3 (aq) H 2 CO 3 (aq) + NaCl(aq) H 2 CO 3 (aq) decomposes immediately. H 2 CO 3 (aq) H 2 O(l) + CO 2 (g)
Type of Reactions in Aqueous Solutions Practice Problems #45-49, page 306
Type of Reactions in Aqueous Solutions Two reactions can be combined and represented by a single chemical reaction.
Type of Reactions in Aqueous Solutions Reaction 1 HCl(aq) + NaHCO 3 (aq) H 2 CO 3 (aq) + NaCl(aq) Reaction 2 H 2 CO 3 (aq) H 2 O(l) + CO 2 (g) Combined equation HCl(aq) + NaHCO 3 (aq) + H 2 CO 3 (aq) H 2 CO 3 (aq) + NaCl(aq) + H 2 O(l) + CO 2 (g) Overall equation HCl(aq) + NaHCO 3 (aq) H 2 O(l) + CO 2 (g) + NaCl(aq)
Transparency 33: Types of Equations
Math Skills Transparency 12: Simplifying Equations
Homework, Section 3 SECTION 3 REVIEW, Page 308 Questions #50-56 Answer with complete sentences Due tomorrow
Key Concepts Some physical changes are evidence that indicate a chemical reaction has occurred. Word equations and skeleton equations provide important information about a chemical reaction. A chemical equation gives the identities and relative amounts of the reactants and products that are involved in a chemical reaction. Balancing an equation involves adjusting the coefficients until the number of atoms of each element is equal on both sides of the equation. Study Guide SECTION 9. 1 Reactions and Equations
Classifying chemical reactions makes them easier to understand, remember, and recognize. Activity series of metals and halogens can be used to predict if single-replacement reactions will occur. Study Guide SECTION 9. 2 Classifying Chemical Reactions Key Concepts
In aqueous solutions, the solvent is always water. There are many possible solutes. Many molecular compounds form ions when they dissolve in water. When some ionic compounds dissolve in water, their ions separate. When two aqueous solutions that contain ions as solutes are combined, the ions might react with one another. The solvent molecules do not usually react. Reactions that occur in aqueous solutions are double-replacement reactions. Study Guide SECTION 9. 3 Reactions in Aqueous Solutions Key Concepts