The process by which one or more substances are changed into one or

more different substances

CHEMICAL REACTIONS

Word EquationsTo write a word equation,

1. Write the names of the reactants to the left of the arrow separated by plus signs;

2. Write the names of the products to the right of the arrow, also separated by plus signs.

Reactant + Reactant Product + Product

EXAMPLEMethane + Oxygen Carbon

dioxide + Water

EXAMPLE 2

Iron + Oxygen Iron(III) Oxide

EXAMPLE 3Hydrogen Peroxide Water and Oxygen

Skeleton EquationsWrite the formulas of the reactants to the

left of the yields sign (arrow) and the formulas of the products to the right.

A skeleton equation is a chemical equation that does not indicate the relative amounts of the reactants and products.Here is the equation for rusting:Fe + O2 Fe2O3

Formula Writing Practice WS

CatalystA catalyst is a substance that speeds up

the reaction but is not used up in the reaction

Without catalyst With Catalyst

Important Symbols

Balancing Chemical Equations

To write a balanced chemical equation,1.Write the skeleton equation2.Use coefficients to balance the equation so that

it obeys the law of conservation of mass. Remember you want the same number of

atoms of each element on each side of the equation.

Example

Example 2

Example 3 -- Try on your own!!!Write a balanced chemical equation for the

reaction in which sodium hydroxide and calcium bromide react to produce solid calcium hydroxide and sodium bromide. (The reaction occurs in water.)

NaOH(aq)+CaBr2(aq) Ca(OH)2(s)+NaBr(aq)

2NaOH(aq)+CaBr2(aq) Ca(OH)2(s)+2NaBr(aq)

Summary

Warm Up!!_____NaClO3 →____ NaCl + __O2

Chemical Equations from Names

Magnesium and Hydrogen Chloride produce Hydrogen and Magnesium Chloride

Calcium Hydroxide and Lithium Chloride produce Lithium Hydroxide and Calcium Chloride

Decompose Copper (II) oxide into Copper and Oxygen

Aluminum and Iron (III) oxide produce iron and aluminum oxide

combustion of Butane (C4H10) in air to produce carbon dioxide and water

Warm Up___AgNO3 + __Ni __Ni(NO3)2 +

__Ag

The Five Types of Reactions

Chemistry with

A + B AB

Synthesis Reactions

1. Synthesis Reactions (Combination)

Two or more reactants produce one product

Examples:NH3 + HCl NH4Cl

H2 + O2 H2O

Ag + S Ag2S

Al + Cl2 AlCl3

Chemistry with

AB A + B

Decomposition Reactions

2. DecompositionOne reactant produces

two or more productsExamples

Ag2O Ag + O2

PCl5 PCl3 +Cl2

H2O2 H2O + O2

CuO Cu + O2

Chemistry with

AB + C AC + B

Single Replacement

3. Single Replacement One element replaces

another elementMust consult the activity

series

3. Single Replacement

One element and one compound producing a different element and compound

ExamplesFe + H3(PO4) H2 + Fe3(PO4)2

H2 + CuO Cu + H2O

Zn + HCl H2 + ZnCl2

Cl2 + KBr Br2 + KCl

Equations Activity Series Worksheet

Chemistry with

AB + CD AD + CB

Double Replacement

4. Double Replacement

A double-replacement reaction is a chemical change involving an exchange of positive ions between two compounds.

Examples:

Al(NO3)3 + NaOH Al(OH)3 + NaNO3

PbCl2 + Li2SO4 PbSO4 + LiCl

ZnBr2 + AgNO3 Zn(NO3)2 + AgBr

BaCl2 + KIO3 Ba(IO3)2 + KCl

4. Double replacementThree main products of a double

replacement reaction Precipitate (solubility table)WaterGas

5. Combustion A combustion reaction

Chemical changeElement or a compound reacts with oxygen Producing energy in the form of heat and

light

5. CombustionA hydrocarbon reacts with oxygen to produce

carbon dioxide and waterExamples:

CH4 + O2 CO2 + H2O

C6H12O6 + O2 CO2 + H2O