9.2 Reactions of Acids with Bases
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D12 - Explain the chemical composition of
acids and bases, and explain the change of
pH in neutralization reactions.
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What is neutralization?
This is a chemical reaction between an acid
and a base.
When neutralization occurs, there are two
products formed …
1. salt
2. water
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What is the ion formed by acids in water?
Hydrogen ion H+ or Hydronium ion H3O+
What is the ion associated with bases?
Hydroxide ion
OHWhat happens when these two molecules get
together?
H3O+ + OH2H2O
H+ + OHH2O
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Remember … not every salt is the “salt” that
you are thinking about!
A “salt” is any ionic compound formed from a
cation (positive ion) and an anion (negative
ion).
While table salt (NaCl) is a “salt,” it is certainly
not the only one out there!
The example of
Hydrochloric acid + Sodium hydroxide (base)
ACID + BASE  SALT + WATER
HCl + NaOH  NaCl + H2O
=
Salt water!
KOH + HNO3  H2O + KNO3
Acid?
HNO3
Base?
KOH
Salt?
KNO3
NH3 + H2O  NH4+ + OHBase – because OH- is present in the products
HClO + LiOH  LiClO + H2O
Neutralization – because of the salt and water in the products
HCl + H2O  H3O+ + ClAcid – because H3O+ is present in the products
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No. Remember that it takes one H+ (or H30+)
to cancel out one OH-.
So, unless the amount of H+ from the acid
and the OH- from the base are balanced, the
resulting solution will not be neutral.
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The pH of final solution depends on the
amounts and strength of the acid and base.
If there is more OH- present than H+, the
resulting solution will be basic.
If there is more H+ present than OH-, the
resulting solution will be acidic.
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What would result from mixing equal
amounts of a weak base and a strong acid?
An acidic solution
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Remember, a salt is another name for an
ionic compound, which is a combination of
cations and anions.
Common salts:
Table salt - NaCl
Baking soda – NaHCO3
Highway de-icers – often CaCO3 and MgCl2
Fire extinguishers – NaHCO3, KHCO3 and
((NH4)H2PO4
Antiperspirants and deodorants - AlK(SO4)2
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Minerals are inorganic elements that come
from the soil and water. Your body needs
minerals to grow and stay healthy. Minerals
contain salts of elements that are needed by
your body
Ca – strong bones and teeth, nerves and
muscles
K and Na – nerve impulses, water content of
cells
P – transportation of energy, DNA replication
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We will use our knowledge of acids and bases
to understand acid rain.