chapter 9: chemical reactions chemistry matter and change

44
Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

Upload: bryce-terry

Post on 26-Dec-2015

259 views

Category:

Documents


3 download

TRANSCRIPT

Page 1: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

Chapter 9: Chemical ReactionsChapter 9: Chemical Reactions

CHEMISTRY Matter and Change

Page 2: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

Section 9.1 Reactions and Equations

Section 9.2 Classifying Chemical Reactions

Section 9.3 Reactions in Aqueous Solutions

ExitClick a hyperlink to view the corresponding slides.

CHAPTER

9 Table Of Contents

Page 3: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Recognize evidence of chemical change.

chemical change: a process involving one or more substances changing into a new substance

chemical reaction

reactant

product

chemical equation

coefficient

• Represent chemical reactions with equations.

• Balance chemical equations.

Chemical reactions are represented by balanced chemical equations.

SECTION9.1

Reactions and Equations

Page 4: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• * is called a chemical reaction.

SECTION9.1

Reactions and Equations

Chemical Reactions

Page 5: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Evidence that a chemical reaction may have occurred:– *

– *

– *

– Gas bubbles

– Appearance of a solid

SECTION9.1

Reactions and Equations

Chemical Reactions (cont.)

Page 6: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Chemists use statements called equations to represent chemical reactions.

• Reactants are the *.

• Products are the *.

• This table summarizes the symbols used in chemical equations.

SECTION9.1

Reactions and Equations

Representing Chemical Reactions

Page 7: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• 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) → AlBr3(s)

• Both word and skeleton equations lack information about how many atoms are involved in the reaction.

SECTION9.1

Reactions and Equations

Representing Chemical Reactions (cont.)

Page 8: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• A chemical equation is a statement that uses chemical formulas to *

SECTION9.1

Reactions and Equations

Representing Chemical Reactions (cont.)

Page 9: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• This figure shows the balanced equation for the reaction between aluminum and bromine.

SECTION9.1

Reactions and Equations

Balancing Chemical Equations

Page 10: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• A coefficient in a chemical equation is the *.

SECTION9.1

Reactions and Equations

Balancing Chemical Equations (cont.)

Page 11: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

SECTION9.1

Reactions and Equations

Balancing Chemical Equations (cont.)

Page 12: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

SECTION9.1

Reactions and Equations

Balancing Chemical Equations (cont.)

Page 13: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

SECTION9.1

Reactions and Equations

Balancing Chemical Equations (cont.)

Page 14: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• The most fundamental law in chemistry is the law of conservation of mass.

• Balanced equations show this law.

SECTION9.1

Reactions and Equations

Balancing Chemical Equations (cont.)

Page 15: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

SECTION9.1

Reactions and Equations

Balancing Chemical Equations (cont.)

Page 16: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Classify chemical reactions.

metal: an element that is a solid at room temperature, a good conductor of heat and electricity, and is generally shiny

• Identify the characteristics of different classes of chemical reactions.

SECTION9.2

Classifying Chemical Reactions

Page 17: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

synthesis reaction

combustion reaction

decomposition reaction

single-replacement reaction

There are four types of chemical reactions: synthesis, combustion, decomposition, and replacement reactions.

double-replacement reaction

precipitate

SECTION9.2

Classifying Chemical Reactions

Page 18: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Chemists classify reactions in order to organize the many types.

• A synthesis reaction is a reaction in which *.

SECTION9.2

Classifying Chemical Reactions

Types of Chemical Reactions

Page 19: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• When two elements react, the reaction is always a synthesis reaction.

SECTION9.2

Classifying Chemical Reactions

Types of Chemical Reactions (cont.)

Page 20: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• In a combustion reaction, *

• Heated hydrogen reacts with oxygen to produce heat and water in a combustion reaction. This is also a synthesis reaction.

SECTION9.2

Classifying Chemical Reactions

Types of Chemical Reactions (cont.)

Page 21: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• A decomposition reaction is one in which *.

• Decomposition reactions often require an energy source, such as heat, light, or electricity, to occur.

SECTION9.2

Classifying Chemical Reactions

Decomposition Reactions

Page 22: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• * is called a single replacement reaction.

A + BX → AX + B

SECTION9.2

Classifying Chemical Reactions

Replacement Reactions

Page 23: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• 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.

SECTION9.2

Classifying Chemical Reactions

Replacement Reactions (cont.)

Page 24: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Halogens frequently replace other halogens in replacement reactions.

• Halogens also have different reactivities and do not always replace each other.

SECTION9.2

Classifying Chemical Reactions

Replacement Reactions (cont.)

Page 25: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Double replacement reactions occur when *.

• This figure shows a generic double replacement equation.

SECTION9.2

Classifying Chemical Reactions

Replacement Reactions (cont.)

Page 26: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• * is called a precipitate.

• All double replacement reactions produce either water, a precipitate, or a gas.

SECTION9.2

Classifying Chemical Reactions

Replacement Reactions (cont.)

Page 27: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• This table shows the steps to write double replacement reactions.

SECTION9.2

Classifying Chemical Reactions

Replacement Reactions (cont.)

Page 28: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• This table summarizes different ways to predict the products of a chemical reaction.

SECTION9.2

Classifying Chemical Reactions

Replacement Reactions (cont.)

Page 29: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Describe aqueous solutions.

solution: a uniform mixture that might contain solids, liquids, or gases

• 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.

SECTION9.3

Reactions in Aqueous Solutions

Page 30: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

aqueous solution

solute

solvent

Double-replacement reactions occur between substances in aqueous solutions and produce precipitates, water, or gases.

complete ionic equation

spectator ion

net ionic equation

SECTION9.3

Reactions in Aqueous Solutions

Page 31: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• An aqueous solution contains one or more *

• The solvent is the *

SECTION9.3

Reactions in Aqueous Solutions

Aqueous Solutions

Page 32: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Water is always the solvent in an aqueous solution.

• There are many possible solutes—sugar and alcohol are molecular compounds that exist as molecules in aqueous solutions.

• Compounds that produce hydrogen ions in aqueous solutions are acids.

SECTION9.3

Reactions in Aqueous Solutions

Aqueous Solutions (cont.)

Page 33: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Ionic compounds can also be solutes in aqueous solutions.

• When ionic compounds dissolve in water, their ions separate in a process called dissociation.

SECTION9.3

Reactions in Aqueous Solutions

Aqueous Solutions (cont.)

Page 34: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• 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.

SECTION9.3

Reactions in Aqueous Solutions

Types of Reactions in Aqueous Solutions

Page 35: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Aqueous solutions of sodium hydroxide and copper(II) chloride react to form the precipitate copper(II) hydroxide.

2NaOH(aq) + CuCl2(aq) → 2NaCl(aq) + Cu(OH)2(s)

• * are called complete ionic equations.

2Na+(aq) + 2OH–(aq) + Cu2+ (aq)+ 2Cl–(aq) → 2Na+(aq) + 2Cl–(aq) + Cu(OH)2(s)

SECTION9.3

Reactions in Aqueous Solutions

Types of Reactions in Aqueous Solutions (cont.)

Page 36: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• * are called spectator ions and are not usually written in ionic equations.

• * are called net ionic equations.

2OH–(aq) + Cu2+(aq) → Cu(OH)2(s)

SECTION9.3

Reactions in Aqueous Solutions

Types of Reactions in Aqueous Solutions (cont.)

Page 37: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Some reactions produce more water molecules.

• No evidence of a chemical reaction is observable.

HBr(aq) + NaOH(aq) → H2O(l) + NaBr(aq)

• Without spectator ions H+(aq) + OH–(aq) → H2O(l).

SECTION9.3

Reactions in Aqueous Solutions

Types of Reactions in Aqueous Solutions (cont.)

Page 38: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Gases that are commonly produced are carbon dioxide, hydrogen cyanide, and hydrogen sulfide.

2HI(aq) + Li2S(aq) → H2S(g) + 2LiI(aq)

SECTION9.3

Reactions in Aqueous Solutions

Types of Reactions in Aqueous Solutions (cont.)

Page 39: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Another example is mixing vinegar and baking soda, which produces carbon dioxide gas.

HCl(aq) + NaHCO3(aq) → H2CO3(aq) + NaCl(aq)

• H2CO3(aq) decomposes immediately.

H2CO3(aq) → H2O(l) + CO2(g)

SECTION9.3

Reactions in Aqueous Solutions

Types of Reactions in Aqueous Solutions (cont.)

Page 40: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• Two reactions can be combined and represented by a single chemical reaction.

SECTION9.3

Reactions in Aqueous Solutions

Types of Reactions in Aqueous Solutions (cont.)

Page 41: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

Reaction 1

HCl(aq) + NaHCO3(aq) → H2CO3(aq) + NaCl(aq)Reaction 2

H2CO3(aq) → H2O(l) + CO2(g)

Combined equation

HCl(aq) + NaHCO3(aq) + H2CO3(aq) → H2CO3(aq) + NaCl(aq) + H2O(l) + CO2(g)

Overall equation

HCl(aq) + NaHCO3(aq) → H2O(l) + CO2(g) + NaCl(aq)

SECTION9.3

Reactions in Aqueous Solutions

Types of Reactions in Aqueous Solutions (cont.)

Page 42: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

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

SECTION9.1

Reactions and Equations

Page 43: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• 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

SECTION9.2

Classifying Chemical Reactions

Key Concepts

Page 44: Chapter 9: Chemical Reactions CHEMISTRY Matter and Change

• 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

SECTION9.3

Reactions in Aqueous Solutions

Key Concepts