Section 8.1
Describing Chemical Change
O
Chapter 8
Chemical Reactions
Adapted from notes by Stephen Cotton
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Chemical Reactions
Symbols in Equations
O Reactants
–
O Products –
O Reactants →
O Arrow
separates reactants from
products.
O (s) =
O (g) =
O (l) =
O (aq) =
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Chemical Reactions
O
Symbols in Equations
Atoms
created or destroyed…
atoms are only rearranged.
O Chemical
rxns/eqns follow the .
.
∆
heat
⎯ ⎯⎯→ , ⎯ ⎯ ⎯⎯→
Sentence: Hydrogen gas and oxygen gas
combine to form water.
O Word Eqn:
O Skeletal Eqn:
O Balanced Eqn:
O
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OBJECTIVES:
– Write equations describing
chemical reactions, using
appropriate symbols
– Write balanced chemical
equations, when given the names
or formulas of the reactants and
products in a chemical reaction.
Pt
⎯⎯⎯→
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Catalyst
O Substance
that
a
reaction without itself being
changed or used up by the
reaction… ex: enzymes.
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Balancing Chemical Equations
O
Change number of atoms with
ONEVER,
EVER change
.
.
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Convert to Equation Form
O
Nitric acid dissolved in water reacts
with solid sodium carbonate to form
liquid water, carbon dioxide gas, and
sodium nitrate dissolved in water.
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Convert to Sentence Form
O
Fe(s) + O2(g) → Fe2O3(s)
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Balancing Examples
O
O
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Mg + N2 → Mg3N2
AgNO3 + Cu → Cu(NO3)2 + Ag
Balancing Examples
OA
chunk of sodium is dropped
into a beaker of water resulting
in the production of a solution of
sodium hydroxide and hydrogen
gas.
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Balancing Examples
and carbon dioxide are
produced when methane (CH4)
reacts with oxygen.
Section 8.2
Types of Chemical Reactions
O Water
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O
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#1 - Combination Reactions
O
O
O
A + B Æ AB
Ca + O2 →
Sulfur trioxide and water react.
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#2 - Decomposition Reactions
AB Æ A + B
O NaCl Æ
O Dihydrogen carbonate
decomposes upon heating.
O
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#3 - Single Replacement
AX + B Æ A + BX
O Metals replace other metals (and
hydrogen) according to the
O
Activity Series of Metals on pg. 217.
Zn + HCl →
O A small piece of sodium is dropped
into a beaker of water and explodes.
O
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OBJECTIVES:
– Identify a reaction as combination,
decomposition, single-replacement,
double-replacement, or combustion
– Predict the products of combination,
decomposition, single-replacement,
double-replacement, and combustion
reactions.
#4 - Double Replacement
AX + BY Æ AY + BX
Reactants must be two ionic
compounds or acids.
O Usually in aqueous solution
O NaOH + FeCl3 →
O
O
O
Calcium chloride is mixed with
sodium hydroxide.
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#5 – Combustion
(of a hydrocarbon)
Means “add oxygen”
O A compound composed of C and H
for sure (and maybe O) reacts with
oxygen.
O If the combustion is complete, the
products will be CO2 and H2O.
O If the combustion is incomplete, the
products will be CO and H2O.
O
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Examples
O (complete)
C6H12O6 + O2 →
O (incomplete)
CH4 + O2 →
O Butane
is combusted…
O If it doesn’t say, assume complete.
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Section 8.3
Reactions in Aqueous Solution
O OBJECTIVES:
–Write and balance net ionic
equations.
–Use solubility rules to predict
the precipitate formed in
double-replacement reactions.
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Molecular, Complete Ionic,
and Net Ionic Equations
O Solutions
of silver nitrate and sodium
chloride are mixed… using the
solubility rules in T.8.3, pg.227, write
the molecular, complete ionic, and net
ionic equations for the reaction…
include the physical state for all
species.
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Molecular, Complete Ionic,
and Net Ionic Equations
O
Solutions of iron(II) nitrate and
aluminum chloride are mixed… using
the solubility rules in T.8.3, pg.227,
write the molecular, complete ionic,
and net ionic equations for the
reaction… include the physical state
for all species.
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