Download Chapter 6 – Chemical Reactions and Equations

Chapter 8 – Chemical Equations and Reactions
I.
Chemical Equations
A.
Chemical Reaction –
1.
2.
3.
4.
B.
Chemical Equation –
1.
Chemical equations must represent all known facts…they
must contain the correct formula for the reactants and
products
2.
Every equation must be “balanced”
a.
The Law of Conservation of Matter requires that
b.
If this is not true, the equation is said to be
“unbalanced”
C.
D.
Terms
1.
Reactants –
2.
Products –
Word and Formula Equations
1.
Word equation – equation in which the reactants and
products in a chemical reaction are represented by words
2.
Formula equation – equation that represents the reactants
and products of a chemical reaction by their symbols or
formulas
E.
Symbols
1.
The reactants and products are separated by either
a.
b.
2.
Each substance on the reactant side and each substance on
the product side is separated by a
3.
The physical state of each substance is indicated by a
symbol in parenthesis after each formula
a.
c.
b.
d.
4.
Special conditions for the reaction may be indicated above
the arrow:
a.
b.
c.
d.
II.
Guidelines for Balancing Chemical Equations
A.
Convert the word equation to a formula equation
B.
There are two types of numbers that are involved in the equation:
1.
The numbers used to balance equations are called
coefficients and are placed in front of the entire chemical
formula
2.
The numbers found after the symbol of and element in a
chemical formula are called subscripts and should NEVER
C.
Helpful Hints for Balancing
 Carbon tetrahydride (methane) reacts with oxygen to form
carbon dioxide and water
1.
Count the number of atoms on each side of the arrow
2.
Using coefficients ONLY, balance the types of atoms that
appear only once on each side of the equation
3.
If there’s an even number of atoms on one side of the
equation and an odd number of atoms (of the same element)
on the other side of the equation, make the odd number
even (usually by multiplying by 2).
4.
Balance any polyatomic ions that appear on both sides of
the equation as single units
D.
More Examples
1.
Water decomposes to form molecular hydrogen and
molecular oxygen
2.
Hydrochloric acid and calcium carbonate react to form
carbon dioxide, water, and calcium chloride
3.
Sodium and oxygen gas react to produce sodium oxide
4.
Ethanol (CH3CH2OH) reacts with oxgen to form carbon
dioxide and water
5.
Aluminum metal submerged in hydrochloric acid produces
aluminum chloride and hydrogen gas
6.
Potassium nitrate breaks down to form potassium nitrite and
molecular oxygen
III.
7.
Aluminum sulfate and calcium hydroxide react to form
aluminum hydroxide and calcium sulfate
8.
Butane (C4H10) burns in the presence of oxygen gas to form
carbon dioxide and water
Types of Chemical Reactions
A.
Synthesis Reactions
1.
Sometimes called combination reactions; occur when 2 or
more substances react to form
2.
B.
General Equation:
Decomposition Reactions
1.
ONLY ONE REACTANT undergoes a reaction to form
2.
General Equation:
C.
Single Displacement
1.
Single replacement (also known as single displacement)
reactions occur when an element and
a compound react and
2.
D.
General Equations:
Double replacement (also known as double displacement)
occurs when
1.
This is also known as a metathesis reaction
2.
General Equation:
3.
Double replacement reactions will generally occur if one of
the following three conditions (“driving forces”) are satisfied:
a.
b.
c.
E.
IV.
Combustion Reactions
1.
Combustion reactions
2.
One of the reactants is
3.
When hydrocarbons,
Activity Series of the Elements
A.
Activity series – a list of elements organized according to the ease
with which the elements undergo certain chemical reactions
B.
Whether or not a single replacement reaction will occur can be
predicted by the activity series
1.
In order for a reaction to occur, the element in question must
be above the element it replaces in the compound
2.
Using the activity series, explain whether each of the
possible reactions listed will occur:
a.
Cd + Pb(NO3)2 
b.
Cu + HCl
c.
Br2 + NaCl 
d.
Mg + Co(NO3)3 
e.
Pt + HNO3 
