Acid and Bases
5.3 and 5.4
-Types of OxidesMany acids and bases are formed by
dissolving oxides in water
At the end of this, you should able
to:
 Classify
oxides as acidic or basic
based on metallic/non-metallic
character
 Give examples of each
 Discuss neutralization reactions
What is an oxide?
 An
oxide is a compound of oxygen
and another element.

Most oxides can be grouped into two
types:

acidic oxides (or non-metal oxide (NMO) produce an aq
sol’n pH less than 7)

basic oxides
(or metal oxides (MO) produce an aq sol’n
pH greater than 7)
Acidic oxides (NMO)
Oxides of non-metal (NMO)
 Acidic oxides are often gases at room
temperature.

Acidic oxides (NMO)

React with water to produce acids.

Example:
sulphur trioxide + water
SO3 + H2O
sulphuric acid
H2SO4
Acidic oxides (NMO)

React with basic oxide (MO) to produce
ternary salts (ionic compound, MNMO).

Example:
sulphur trioxide + sodium oxide
SO3 + Na2O
sodium sulphate
Na2SO4
Acidic oxides

React with bases to produce salts and water
Example:
carbon dioxide + sodium hydroxide
CO2 + 2NaOH
sodium carbonate + water
Na2CO3 + H2O
Examples of acidic oxides
Acidic Oxide
Formula
Acid Produced with
Water
sulphur trioxide
SO3
sulphuric acid, H2SO4
sulphur dioxide
SO2
sulphurous acid, H2SO3
carbon dioxide
CO2
carbonic acid, H2CO3
phosphorous(V)
oxide
P4O10
phosphoric acid, H3PO4
Facts about Acidic Oxides

When CO2 (from combustion
reactions) reacts with H20 in
the atmosphere, carbonic
acid is formed. The acidity
(low pH) produced is of
concern to all aquatic animals
that have shells like
zooplankton, snails,
crab…since it thins their
shells... making them weaker,
more prone to infection…all
food webs are affected too.


Nitrogen monoxide
produced in the car
engine is a respiratory
irritant. It is mostly
removed from the
exhaust with a catalytic
converter
Sulphur trioxide
produces sulphuric acid
which comes down as
acidic rain and snow and
destroys aquatic and
terrestrial ecosystems
Basic oxides (MO)

Oxides of metal (MO)
 Basic oxides are often solids at room
temperature.
 Most basic oxides are
insoluble in water.
Calcium oxide (quicklime)
Basic oxides (MO)

React with non-metal oxides (NMO) to
produce ternary salts (ionic compounds,
MNMO)

Example:
Magnesium oxide + carbon dioxide
MgO + CO2
magnesium carbonate
MgCO3
Basic oxides (MO)

React with acids to produce salts and
water only.

Example:
Magnesium oxide + hydrochloric acid
MgO + 2HCl
magnesium chloride + water
MgCl2 + H2O
This is a neutralisation reaction
Examples of basic oxides
Basic Oxide
Formula
magnesium oxide
MgO
sodium oxide
Na2O
calcium oxide
CaO
copper(II) oxide
CuO
Facts about basic oxides


CaO is called lime. Adding
 NaOH is the most
CaO to acidic lakes by
widely used chemical in
dropping it from a plane
the world- billions of kg
results in a less acidic lake or
of sodium hydroxide is
neutral lake and is called
made and sold all over
“liming”
the world
When lime is added to water,
it forms a solution of calcium  NaOH is used to make
hydoxide(quicklime)...
paper, detergent,
important in glass, paper and
aluminum…thousands
cement
of products
Neutralization Reactions…upset
stomach…too much acid?

Try a Tums (CaCO3)
 It is a ternary salt with a
polyatomic ion. It will
react with HCl in the
stomach and produce
CaCl2 and H2CO3 which
further breaks down to
CO2 and H2O
 + no more acidity, Ca +2
ions absorbed… good
for bones
 - gas produced…





Try milk of magnesia
(Mg(OH)2)
Only slightly soluble in
water so the basic
characteristics not felt in
the mouth and
esophagus (aq.). MgCl2
and H2O produced
+ no more acidity
- difficult to swallow
since slightly bitter
Do not try NaOH…very
soluble in water…ouch!
Acids and Bases in Action



Acid rain causes a
decrease in reproduction
and a crash in
populations especially
aquatic ones. A lake
can be treated with lime.
Some lakes are affected
more (N Ont., ground is
granite) and others less
(S Ont., ground is
limestone) by acid rain.
Limestone= nature’s
natural antacid




Leavening agents=
substances that produce CO2
gas in baking
Citric acid (from fruit) reacts
with baking soda (NaHCO3)
creating CO2 gas, sodium
citrate and water
Baking powder has dry
tartaric acid and baking soda.
It is activated by moisture.
Recycling of car battery parts
requires the work of acids
and bases…great example of
chemistry at work
Both an Acid and a Base! Sodium
Hydrogen Carbonate…it rhymes

NaHCO3
 Can react with a
strong acid to
produce a salt, water
and carbon dioxide
thus acting as a
base (proton
acceptor)
 NaHCO3 + HCl →
H2CO3 + NaCl →
H2O + CO2 + NaCl

NaHCO3
 Can react with a
strong base to form
a salt and water thus
acting as an acid
(proton donor)
 NaHCO3 + NaOH =
Na2CO3 + H2O