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Temperature change
Release of energy (heat or light)
Color Change
Odor
Gas Bubbles
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All chemical reactions have two parts:
Reactants and Products.
Reactants  Products
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Example:
aluminum(s) + bromine(l)  aluminum
bromide(s)
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Example:
aluminum(s) + bromine(l)  aluminum
bromide(s)
Skeleton equation:
Al (s) + Br2 (l)  AlBr3 (s)
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Hydrogen and bromine gases react to yield
hydrogen bromide.

hydrogen (g) + bromine (g)  hydrogen bromide (g)
 H2 (g) + Br2 (g)  HBr (g)
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Carbon monoxide and oxygen react to form
carbon dioxide.

carbon monoxide (g) + oxygen (g)  carbon dioxide
(g)
 CO (g) + O2 (g)  CO2 (g)
Step 1: Write a skeleton equation from a word
equation
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Step 2: Count all of the atoms in the reactants
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Hydrogen (g) + Chlorine (g) 
H2 (g) + Cl2 (g)  HCl (g)
H2 (g) + Cl2 (g)  HCl (g)
2
2
Step 3: Count number of atoms in products
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H2 (g) + Cl2 (g)  HCl (g)
2 atoms total
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Step 4: Change the coefficients to make the
number of atoms of each element equal on both
sides of the equation.
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H2 (g) + Cl2 (g)  2HCl
2
2
4
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Write a balanced chemical equation for the
reaction in which aqueous sodium hydroxide and
aqueous calcium bromide produce solid calcium
hydroxide and aqueous sodium bromide.
NaOH(aq) + CaBr2(aq)  Ca(OH)2(s) + NaBr(aq)
How many atoms in the reactants?
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How many atoms in the products?
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5
7
Balanced equation:
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2NaOH(aq) + CaBr2(aq)  Ca(OH)2 + 2NaBr(aq)
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Synthesis
Combustion
Decomposition
Replacement (Single-Replacement, DoubleReplacement)
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Two reactants form one product
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It can either be two elements or two
compounds reacting to form a new compound.
Example:
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A + B  AB
CaO(s) + H2O(l)  Ca(OH)2
An element and a compound can also combine
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Example:
SO2(g) + O2(g)  SO3(g)
2SO2(g) + O2(g)  2SO3(g)
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This is when a compound breaks down into
two or more elements or other compounds
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AB  A + B
Example:
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NaN3(s)  Na(s) + N2(g)
Balanced?
2NaN3(s)  2Na(s) + 6N2(g)
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A compound reacts with an element and one
element replaces one of the atoms.
A + BX  AX + B
Example:
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Li(s) + H2O(l)  LiOH(aq) + H2(g)
2Li(s) + 2H2O(l)  2LiOH + H2(g)
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AX + BY  AY + BX
Example:
Ca(OH)2(aq) + HCl(aq)  CaCl2(aq) + H2O (l)
 Balanced?
 Ca(OH)2(aq) + 2HCl(aq)  CaCl2(aq) + 2H2O (l)
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In combustion reactions Oxygen combines with
a substance and releases energy in the form of
heat and light. (FIRE)
A common example of this is burning coal
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C(s) + O2 (g)  CO2
Another common example is the combustion of
hydrogen to make water.
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H2(g) + O2(g)  H2O (g)
2H2(g) + O2(g)  2H2O(g)
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An aqueous solution contains one or more
dissolved substances called solutes.
In an aqueous solution the solvent is water.
In an aqueous solution of Hydrocholric acid…
HCl(aq)  H+(aq) + Cl-(aq)
In an aqueous solution of sodium hydroxide
NaOH(aq)  Na+(aq) + OH-(aq)
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1. All salts of Group IA, and ammonium are soluble.
2. All salts of nitrates, chlorates and acetates are
soluble.
3. All salts of halides are soluble except those of
silver(I), copper(I), lead(II), and mercury(I).
4. All salts of sulfate are soluble except for barium
sulfate, lead(II) sulfate, and strontium sulfate.
5. All salts of carbonate, phosphate and sulfite are
insoluble, except for those of group IA and
ammonium.
6. All oxides and hydroxides are insoluble except for
those of group IA, calcium, strontium and barium.
7. All salts of sulfides and insoluble except for those
of Group IA and IIA elements and of ammonium.
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Some reactions that occur in aqueous solution
produce solid precipitates.
For example…
2NaOH(aq) + CuCl2(aq)  2NaCl(aq) +
Cu(OH)2(s)
An ionic equation shows in detail the ions that
exist in the solution…
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Write the ionic equations and the net ionic
equation for the reactions…
Ba(NO3)2(aq) + Na2CO3(aq)  BaCO3(s) +
NaNO3(aq)
Write the chemical, complete ionic, and net
ionic equations for the reaction between
aqueous solutions of barium nitrate and
sodium carbonate that forms the precipitate
barium carbonate.
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Acid-Base neutralizations are usually double
replacement reactions that result in the
formation of water.
In general an acid is a compound that, when
dissolved in water produces H+ ions.
Examples – HCl, HBr, H2SO4
In general a base is a compound that, when
dissolved in water produces OH- ions.
Examples: NaOH
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Complete ionic equation:
H+(aq) + Br-(aq) + Na+(aq) + OH-(aq) 
Na+(aq) + Br-(aq) + H2O(l)
Net ionic equation:
H+(aq) + OH-(aq)  H2O(l)
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Write a chemical, complete ionic, and net ionic
equations for the reaction between
hydrochloric acid and aqueous lithium
hydroxide. This reaction produces water and
aqueous lithium chloride.
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Aqueous barium chloride and aqueous sodium
fluoride are mixed.
Aqueous copper (I) nitrate and aqueous
potassium sulfide are mixed
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Aqueous sodium hydroxide and aqueous
copper (II) chloride are mixed.
Aqueous sodium carbonate and aqueous
calcium nitrate are mixed.
Aqueous sodium sulfate and aqueous
potassium carbonate are mixed.