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Chapter 8Chapter 8
Chemical Chemical Equations Equations and and ReactionsReactions
8-1 Describing Chemical Reactions8-1 Describing Chemical Reactions
Chemical reaction – process by which one Chemical reaction – process by which one or more substances are changed into one or more substances are changed into one or more different substancesor more different substances
Reactants – starting substancesReactants – starting substancesProducts – ending substancesProducts – ending substancesConservation of mass tells us that the Conservation of mass tells us that the
mass of the reactants must be equal to the mass of the reactants must be equal to the mass of the productsmass of the products
8-1 Chemical Equations8-1 Chemical Equations Chemical equation – represents (with symbols and Chemical equation – represents (with symbols and
formulas) the identities and relative amounts of the formulas) the identities and relative amounts of the reactants and products in a chemical reactionreactants and products in a chemical reaction
8-1 Signs of a Chemical Reaction8-1 Signs of a Chemical Reaction
Evolution of heat and lightEvolution of heat and light Production of a Production of a
gas/bubblesgas/bubbles Formation of a precipitateFormation of a precipitate Color changeColor change
8-1 Requirements for Properly 8-1 Requirements for Properly Written Chemical EquationsWritten Chemical Equations
All reactants and products must be All reactants and products must be representedrepresented
Correct symbols and formulas must be Correct symbols and formulas must be used for all substances in the equation used for all substances in the equation (remember diatomics!)(remember diatomics!)
Reactants on left, products on rightReactants on left, products on rightArrow means “yields” or “forms”Arrow means “yields” or “forms”Law of conservation of matter must be Law of conservation of matter must be
satisfied – equations must be BALANCEDsatisfied – equations must be BALANCED
8-1 Balancing Chemical Equations8-1 Balancing Chemical Equations
Equations must be balanced to show the Equations must be balanced to show the same number of atoms of each type on same number of atoms of each type on both sides of the equationboth sides of the equation
Balance equations by writing coefficientsBalance equations by writing coefficientsCoefficient – a small whole number that Coefficient – a small whole number that
appears in front of a formula in a chemical appears in front of a formula in a chemical equationequation
NEVER change subscripts!NEVER change subscripts!
8-1 Balancing Equations8-1 Balancing Equations
Write a balanced chemical equation for the Write a balanced chemical equation for the formation of ammonia from its elements. formation of ammonia from its elements.
8-1 Balancing Chemical Equations8-1 Balancing Chemical Equations
Write a balanced chemical equation for the Write a balanced chemical equation for the decomposition of sodium chloride to its decomposition of sodium chloride to its elements. elements.
8-1 Word and Formula Equations8-1 Word and Formula Equations
It is often helpful to begin by writing a word It is often helpful to begin by writing a word equation that represents all the facts about equation that represents all the facts about a chemical reaction. a chemical reaction.
In a word equation, reactants and products In a word equation, reactants and products are represented by words.are represented by words.
methane + oxygen methane + oxygen carbon dioxide + water carbon dioxide + water
8-1 Word and Formula Equations8-1 Word and Formula Equations
A formula equation represents the A formula equation represents the reactants and products of a chemical reactants and products of a chemical reaction by their symbols or formulas.reaction by their symbols or formulas.
CHCH44 + O + O22 CO CO22 + H + H22O (unbalanced)O (unbalanced)
8-1 Additional Symbols Used in 8-1 Additional Symbols Used in Chemical EquationsChemical Equations
(s)(s)
(l)(l)
(aq)(aq)
(g)(g)
YieldsYields
SolidSolid
LiquidLiquid
AqueousAqueous
gasgas
8-1 Reversible Reactions8-1 Reversible Reactions
A reversible reaction is one in which A reversible reaction is one in which products can re-form the original reactantsproducts can re-form the original reactants
3Fe(s) + 4H3Fe(s) + 4H22O(g) FeO(g) Fe33OO44(s) + 4H(s) + 4H22(g)(g)
8-1 Reactions Requiring Heat8-1 Reactions Requiring Heat
Some reactions will only Some reactions will only proceed if the reactants proceed if the reactants are heated. are heated.
2HgO(s) 2HgO(s) 2Hg(l) + O 2Hg(l) + O22(g)(g)
8-1 Practice8-1 Practice
Translate the following into a sentence:Translate the following into a sentence:
2NaOH(aq) + MgCl2NaOH(aq) + MgCl22(aq) (aq) 2NaCl(aq) + Mg(OH) 2NaCl(aq) + Mg(OH)22(s)(s)
NaCl(aq) + AgNONaCl(aq) + AgNO33(aq) (aq) NaNO NaNO33(aq) + AgCl(s)(aq) + AgCl(s)
8-1 Practice8-1 Practice
Write a balanced chemical equation for the Write a balanced chemical equation for the following processes:following processes:
Solid calcium reacts with solid sulfur to Solid calcium reacts with solid sulfur to produce solid calcium sulfide.produce solid calcium sulfide.
Hydrogen gas reacts with fluorine gas to Hydrogen gas reacts with fluorine gas to produce hydrogen fluoride gas. produce hydrogen fluoride gas.
8-2 Types of Chemical Reactions 8-2 Types of Chemical Reactions
Using generalizations about the ways Using generalizations about the ways various substances interact with each various substances interact with each other, we can predict the products of other, we can predict the products of reactionsreactions
There are five main types of chemical There are five main types of chemical reactions. reactions.
8-2 Types of Chemical Reactions8-2 Types of Chemical Reactions
SynthesisSynthesisDecompositionDecompositionSingle replacementSingle replacementDouble replacementDouble replacementCombustion (of hydrocarbons)Combustion (of hydrocarbons)
8-2 Synthesis Reactions8-2 Synthesis Reactions
Two or more substances react to form one Two or more substances react to form one new compoundnew compound
A + X A + X AX AX
Recognize by SINGLE PRODUCTRecognize by SINGLE PRODUCT
8-2 Synthesis Reactions8-2 Synthesis Reactions
Reactions of elements with oxygen or Reactions of elements with oxygen or sulfur FORM OXIDES OR SULFIDESsulfur FORM OXIDES OR SULFIDES
Magnesium reacts with oxygenMagnesium reacts with oxygen
Barium reacts with sulfurBarium reacts with sulfur
Rubidium reacts with sulfurRubidium reacts with sulfur
8-2 Synthesis Reactions8-2 Synthesis Reactions
Reactions of metals with halogens FORM Reactions of metals with halogens FORM METAL HALIDESMETAL HALIDES
Sodium reacts with chlorineSodium reacts with chlorine
Potassium reacts with iodinePotassium reacts with iodine
Magnesium reacts with fluorineMagnesium reacts with fluorine
8-2 Synthesis Reactions8-2 Synthesis Reactions
Metal oxides react with water to form Metal oxides react with water to form metal hydroxidesmetal hydroxides
Calcium oxide reacts with waterCalcium oxide reacts with water
Magnesium oxide reacts with waterMagnesium oxide reacts with water
8-2 Synthesis Reactions8-2 Synthesis Reactions
Nonmetal oxides react with water to form Nonmetal oxides react with water to form acidsacids
Sulfur dioxide reacts with waterSulfur dioxide reacts with water
Carbon dioxide reacts with waterCarbon dioxide reacts with water
8-2 Decomposition Reactions8-2 Decomposition Reactions
A single compound breaks down to A single compound breaks down to produce two or more simpler substancesproduce two or more simpler substances
AX AX A + X A + X
Recognize by single reactantRecognize by single reactant
Often require energy in the form of heat, Often require energy in the form of heat, light or electricity.light or electricity.
8-2 Decomposition Reactions8-2 Decomposition Reactions
Decomposition of binary compounds Decomposition of binary compounds produces elementsproduces elements
Decomposition of waterDecomposition of water
Decomposition of sodium chlorideDecomposition of sodium chloride
Decomposition of magnesium mercury (II) Decomposition of magnesium mercury (II) oxideoxide
8-2 Decomposition Reactions8-2 Decomposition Reactions
Decomposition of metal carbonates Decomposition of metal carbonates FORMS METAL OXIDE AND CARBON FORMS METAL OXIDE AND CARBON DIOXIDEDIOXIDE
Decomposition of calcium carbonateDecomposition of calcium carbonate
Decomposition of magnesium carbonateDecomposition of magnesium carbonate
8-2 Decomposition Reactions8-2 Decomposition Reactions
Decomposition of metal hydroxides Decomposition of metal hydroxides FORMS METAL OXIDES AND WATERFORMS METAL OXIDES AND WATER
Decomposition of calcium hydroxideDecomposition of calcium hydroxide
Decomposition of copper (II) hydroxideDecomposition of copper (II) hydroxide
8-2 Decomposition Reactions8-2 Decomposition Reactions
Decomposition of metal chlorates FORMS Decomposition of metal chlorates FORMS METAL CHLORIDES AND OXYGENMETAL CHLORIDES AND OXYGEN
Decomposition of potassium chlorateDecomposition of potassium chlorate
Decomposition of sodium chlorateDecomposition of sodium chlorate
8-2 Decomposition Reactions8-2 Decomposition Reactions
Decomposition of acids PRODUCES Decomposition of acids PRODUCES NONMETAL OXIDES AND WATERNONMETAL OXIDES AND WATER
Decomposition of carbonic acidDecomposition of carbonic acid
Decomposition of sulfuric acidDecomposition of sulfuric acid
8-2 Single Replacement Reactions8-2 Single Replacement Reactions
One element replaces another similar One element replaces another similar element in a compoundelement in a compound
A + BX A + BX AX + B AX + B
OROR
Y + BX Y + BX BY + X BY + X
8-2 Single Replacement Reactions8-2 Single Replacement Reactions
Replacement of a metal by another metalReplacement of a metal by another metalAluminum reacts with lead nitrateAluminum reacts with lead nitrate
Sodium reacts with iron (II) chlorideSodium reacts with iron (II) chloride
Calcium reacts with aluminum phosphateCalcium reacts with aluminum phosphate
8-2 Single Replacement Reactions8-2 Single Replacement Reactions
Replacement of hydrogen by a metalReplacement of hydrogen by a metalSodium reacts with waterSodium reacts with water
Magnesium reacts with hydrochloric acidMagnesium reacts with hydrochloric acid
Calcium reacts with nitric acidCalcium reacts with nitric acid
8-2 Single Replacement Reactions8-2 Single Replacement Reactions
Replacement of HalogensReplacement of HalogensChlorine reacts with potassium bromideChlorine reacts with potassium bromide
Fluorine reacts with sodium chlorideFluorine reacts with sodium chloride
Fluorine reacts with potassium iodideFluorine reacts with potassium iodide
8-3 Activity Series of the Elements8-3 Activity Series of the Elements
An activity series is a list of elements organized An activity series is a list of elements organized according to the ease with which the elements according to the ease with which the elements undergo certain chemical reactionsundergo certain chemical reactions
For metals, greater activity means greater ease For metals, greater activity means greater ease of LOSS OF ELECTRONS to form cations.of LOSS OF ELECTRONS to form cations.
For nonmetals, greater activity means greater For nonmetals, greater activity means greater ease of GAIN OF ELECTRONS to form anions.ease of GAIN OF ELECTRONS to form anions.
An activity series can be used to determine An activity series can be used to determine whether or not a single replacement reaction will whether or not a single replacement reaction will take place. take place.
8-3 Activity Series8-3 Activity Series
More active metals are More active metals are HIGHER on the list.HIGHER on the list.
A more active metal can A more active metal can replace a less active replace a less active metal on the activity metal on the activity series. series.
Example: Na + CoClExample: Na + CoCl22 Example: Cu + AlClExample: Cu + AlCl33 Example: Cr + HCl Example: Cr + HCl Example: Au + MgSOExample: Au + MgSO44
8-3 Activity Series8-3 Activity Series
Example: ClExample: Cl22 + NaBr + NaBr Example: BrExample: Br22 + KF + KF Example: ClExample: Cl22 + MgBr + MgBr22
8-2 Double Replacement Reactions8-2 Double Replacement Reactions
The ions of two compounds exchange The ions of two compounds exchange places to form two new compoundsplaces to form two new compounds
One of the products is usually a One of the products is usually a precipitate, gas or molecular compound precipitate, gas or molecular compound (like water)(like water)
AX + BY AX + BY AY + BX AY + BX
8-2 Double Replacement Reactions8-2 Double Replacement Reactions
Formation of a precipitateFormation of a precipitatePotassium iodide reacts with lead (II) Potassium iodide reacts with lead (II)
nitratenitrate
Magnesium chloride reacts with sodium Magnesium chloride reacts with sodium hydroxidehydroxide
8-2 Double Replacement Reactions8-2 Double Replacement Reactions
Formation of a gasFormation of a gas Iron (II) sulfide reacts with hydrochloric Iron (II) sulfide reacts with hydrochloric
acidacid
8-2 Double Replacement Reactions8-2 Double Replacement Reactions
Formation of waterFormation of waterAn acid reacts with a base – also called a An acid reacts with a base – also called a
NEUTRALIZATION reactionNEUTRALIZATION reactionHydrochloric acid reacts with sodium Hydrochloric acid reacts with sodium
hydroxidehydroxide
Sulfuric acid reacts with potassium Sulfuric acid reacts with potassium hydroxidehydroxide
8-2 Combustion Reactions8-2 Combustion Reactions
A substance combines with oxygen, A substance combines with oxygen, releasing a large amount of energy in the releasing a large amount of energy in the form of light and heatform of light and heat
Hydrocarbons burn in oxygenHydrocarbons burn in oxygenA hydrocarbon is a compound composed A hydrocarbon is a compound composed
of hydrogen and carbonof hydrogen and carbon
8-2 Combustion Reactions8-2 Combustion Reactions
Combustion of hydrocarbonsCombustion of hydrocarbonsWhen a hydrocarbon reacts with oxygen, When a hydrocarbon reacts with oxygen,
the products are carbon dioxide and waterthe products are carbon dioxide and waterCombustion of butaneCombustion of butane
Combustion of heptaneCombustion of heptane
8-2 Simple Hydrocarbons (C8-2 Simple Hydrocarbons (CnnHH2n+22n+2))
CHCH44
CC22HH66
CC33HH88
CC44HH1010
CC55HH1212
CC66HH1414
CC77HH1616
CC88HH1818
CC99HH2020
CC1010HH2222
methanemethane ethaneethane propanepropane butanebutane pentanepentane hexanehexane heptaneheptane octaneoctane nonanenonane decanedecane
It’s over!It’s over!