Download Chemical Reactions (I)

Chemical Reactions (I)
One classification of chemical reaction is combustion
reactions. A combustion reaction is a very rapid reaction of
reactions take the form:
fuel + oxygen
oxides + energy
The most common fuels burned are called hydrocarbons
(compounds containing hydrogen and carbon also called
fossil fuels because of their origins in living matter).
Complete combustion of hydrocarbons produces only
water and carbon dioxide
hydrocarbon + oxygen
carbon dioxide + water + energy
Incomplete combustion occurs when there is not enough
oxygen available. With incomplete combustion two
additional products are formed, carbon (soot) and carbon
monoxide.
Carbon monoxide is a clear colourless odourless gas that is
highly poisonous.
How do matches work?
Chemical Reactions (II)
Another classification of reactions has four categories:
i) synthesis
ii) decomposition
iii) single replacement
iv) double replacement
Synthesis Reactions
Involve combining smaller atoms and/or molecules into
larger molecules
Also called combination reactions
Are in the form
A+B
AB
A and B do not have to be elements but if they are, it is
definitely a synthesis reaction.
i.e.
hydrogen + oxygen
water
Write a balanced chemical equation for this reaction
Decomposition Reactions
Involve the splitting of a large molecule into elements or
smaller molecules
Are in the form
AB
A+B
If AB is a binary coumpound and the only reactant, the
reaction must be a decomposition reaction.
i.e.
water
hydrogen + oxygen
Chemical Reactions (III)
Single Displacement Reactions
Where either a metal displaces the cation of a compound
i.e.
Mg + 2AgNO3
2Ag + Mg(NO3)2
or where a nonmetal displaces the anion of a compound
i.e.
Br2 + CaI2
I2 + CaBr2
in general,
A + BC
B + AC (A is a metal)
or
A + BC
C + BA (A is a nonmetal)
Double Displacement Reactions
Best described as
AB + CD
i.e. Pb(NO3) 2 + 2KI
AD + CB
2KNO3 + PbI2
Particle Theory of Matter
1.
2.
3.
All matter is made up of tiny partcles.
The particles of matter are in constant motion.
The particles of matter are attracted to one another.
Why reactions take place? The attractive forces and
bonds that hold chemical compounds in certain
configurations must be broken. In order to do this energy
must be provided. It is felt that the energy required to
break apart molecules comes from the collisions between
moving particals. This is called The Collision Model
Rates of Reaction
Microscopic factors effecting the rate at which a chemical
reaction occurs include:
i) The number of collisions that take place
ii) The percentage of collisions that are "effective"
Macroscopic factors include:
a)
b)
c)
d)
Temperature
Concentration
Surface Area
Catalysts
(ii)
(i)
(i)
(ii)
Explosions are chemical reactions that occur at an
incredibly high rate. They often produce huge volumes of
very hot gases that expand and apply forces to anything in
their surroundings.
NH4NO3 is a powerful explosive which is also an
ingredient in many fertilizers.
NaN3 (sodium azide) is the explosive used in air bags.