The document discusses different types of chemical reactions: 1) Decomposition reactions involve a single compound breaking down into simpler substances. An example is calcium carbonate decomposing to calcium oxide and carbon dioxide. 2) Combination reactions involve two substances combining to form a new compound. An example is calcium oxide and sulfur dioxide combining to form calcium sulfite. 3) Single replacement reactions involve an element replacing another in a compound. An example is copper displacing silver from silver nitrate. 4) Double replacement reactions involve ion exchange between two compounds in solution and forming a precipitate. An example is silver nitrate and sodium chloride forming silver chloride and sodium nitrate precipitates. 5) Combustion reactions

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2. Chemical Reaction
 A chemical reaction occurs when one or more
chemicals react to become different chemicals.
 A chemical reaction is characterized by the re-
arrangement of atoms from the reactant side of
the equation to the product side.
-: Example :-
Hydrogen gas burns in oxygen to make water.
2H2 + O2 2H2O

3. Types of Chemical Reaction
 Decomposition Reactions
 Combination Reactions
 Single-Replacement Reactions
 Double-Replacement Reactions
 Combustion Reactions

4. Decomposition Reaction
A decomposition reaction is a reaction in which
a single compound decomposes to two or more
other substances.
AB A+B
Where A and B can be elements or compounds.
Most compounds can be broken down into simpler
substances or decomposed.

5. Decomposition Reaction
-: Example :-
The industrial preparation of calcium oxide (Lime)
involves the decomposition of calcium carbonate
by heating it.
CaCO3(s) CaO(s) + CO2(g)

6. Combination Reaction
A combination reaction is a reaction in which
two substances combine to form a third.
A+B AB
Where A and B can be elements or compounds.
Decomposition and combination reactions can
be considered to be the reverse of each other.

7. Combination Reaction
-: Example :-
The reaction of calcium oxide with sulfur dioxide
to form calcium sulfite
CaO(s) + SO2(g) CaSO3(s)

8. Single-Replacement Reaction
A single-replacement reaction is a reaction in
which an element reacts with a compound and
replaces another element in the compound.
A + BC AB + C
Where A and C are elements and BC and AB are
compounds.

9. Single-Replacement Reaction
-: Example :-
The reaction in which copper displaces silver
from an aqueous solution of silver nitrate
Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s)

10. Double-Replacement Reaction
A double-replacement reaction is a reaction in
which there is an exchange of positive ions between
two compounds. These reactions generally take
place between two ionic compounds in aqueous
solution.
AB + CD AD + CB
Where A and C are cations and B and D are anions.
For a double-replacement reaction to occur, at least
one of the products must be a gas or water, or a
precipitate.

11. Double-Replacement Reaction
-: Example :-
Precipitation reactions are one type of double-
replacement reaction.
AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq)

12. Combustion Reaction
 A combustion reaction is a reaction in which a
substance reacts with oxygen, usually with the fast
release of heat and the production of a flame.
 Organic compounds usually burn in the oxygen in air
to produce carbon dioxide and if the compound
contains hydrogen, another product will be water.
 For example butane burns in air as follows.

13. Combustion Reaction
-: Example :-
In general:
CxHy + O2 CO2 + H2O
Products in combustion are ALWAYS carbon dioxide
And water.
Combustion is used to heat homes and run
automobiles (octane, as in gasoline, is C8H18).

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