Reaction Types
How do we know what will be
produced in a chemical reaction?
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Recognizing a pattern of reactivity gives a
broader understanding than memorizing a
large number of reactions
Would expect elements of the same family
to behave similar
2K + 2H2O → 2KOH + H2
What will happen if Na combines with
water?
Five Types of Reactions
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Combustion – rapid reaction that produces
flame
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Occurs in hydrocarbons (compounds of C, H,
and sometimes O)
Reaction of hydrocarbon with oxygen to
produce carbon dioxide and water
C3H8 + 5O2 → 3CO2 + 4H2O
2CH3OH + 3O2 → 2CO2 + 4H2O
Combination or Synthesis
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Two reactants combine to form a single
product
A + B → AB
Examples
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C + O2 → CO2
N2 + 3H2 → 2NH3
CaO + H2O → Ca(OH)2
Decomposition
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Single reactant breaks apart to form two or
more substances
AB → A + B
Examples
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2KClO3 → 2KCl + 3O2
CaCO3 → CaO + CO2
Single Replacement
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One element replaces another similar
element in a compound
A + BX → AX + B
Examples
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Fe + 2HCl → FeCl2 + H2
Zn + CuSO4 → ZnSO4 + Cu
Na + 2H2O → 2NaOH + H2
Double Replacement
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Atoms exchange partners
Also called metathesis reactions
AX + BY → AY + BX
We will look at two types of double
replacement
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Acid-base reactions
Precipitation reactions
Acid-Base Reactions
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Acid – substance that increases the H+
concentration in aqueous solutions
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HCl → H+ + ClH2SO4 → H+ + HSO4HSO4 → H+ + SO42-
Base
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Increases the OH- concentration
NaOH → Na + OHNH3 + H2O → NH4+ + OH-
Neutralization
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Acids and bases react together to produce a
salt (ionic compound) and water
HCl + NaOH → NaCl + H2O
Write a balanced equation for the reaction
of hydrobromic acid, HBr, with barium
hydroxide, Ba(OH)2.
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Write the balanced equation for the
reaction between phosphoric acid, H3PO4,
and potassium hydroxide.
Precipitation Reaction
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Double replacement that forms a
precipitate
KI (aq) + Pb(NO3)2 (aq) → PbI2 (s) +
2KNO3 (aq)
Example
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When sodium phosphate and barium nitrate
are mixed, a precipitate of barium
phosphate forms. Write the balanced
equation.
Example
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When aqueous sodium hydroxide and
magnesium nitrate are mixed, a magnesium
hydroxide precipitate forms. Write the
balanced chemical equation.