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
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).
