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Recall: Products of Ideal combustion are
not harmful…but…
5.3 Elements and Their Oxides
Products of real combustion are nonmetal oxides…what happens when they
get released into the atmosphere and
contact water vapour?
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What is an oxide?
Oxides (the synthesis story is not over)
Fe2O3
An oxide is a compound of any element
combined with oxygen
Oxides form when an element reacts with
oxygen (usually in the air)
eg.
2 Mg (s) + O2 (g)  2 MgO (s)
N2 (g) + O2 (g)  NO2 or NO3 or NO or…NOx
Recall: What is an acid?
 An acid is a compound that produces
hydrogen ions when mixed with water. The
more H + ions, the more acidic the
solution.
Recall: What is a base?
A base is a
solution that has
OH- ions when
mixed with water.
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Properties of Oxides
pH Scale
 pH is a measure of how acidic or basic a
solution is.
• The pH scale ranges from 0 to 14.
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•
Acidic solutions have pH values below 7
A solution with a pH of 0 is very acidic.
A solution with a pH of 7 is neutral.
Pure water has a pH of 7.
• Basic solutions have pH values above 7.
Non-metal + Oxygen
 Non-metals react with
oxygen to produce nonmetallic oxides which are
gases at room
temperature.
Metal + Oxygen
 Metals react to produce
metallic oxides which tend
to be ionic solids at room
temperature.
 S (s) + O2 (g)  SO2 (g)
 Ca (s) + O2 (g)  CaO (s)
Oxides on their own are not a big problem,
except…..
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Oxides + Water
produce strong acids and bases
Non-metal oxide + water
 When dissolved in water
non-metal oxides from
acids.
Metal Oxide + water
 When dissolved in water
metal oxides form bases.
 SO2 (g) + H2O (l)  H2SO4 (aq)
 CaO (s) + H2O (l)  Ca(OH)2 (aq)
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Primary Emissions from Automobiles
 Carbon monoxide (CO)
 Oxides of nitrogen (NO, NO2)
 Carbon as soot or particulates (C)
 Unburned fuel (hydrocarbons, CxHy)
 Carbon dioxide (CO2)
 Water (H2O)
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Non-Metal Oxides
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Carbon Oxides, COx
C + O2  COx
CARBON MONOXIDE
CO is POISIONOUS because it reduces the ability of
blood to bring oxygen to the body’s cells and tissues.
Remember that oxygen is needed for the combustion that gives our
bodies energy.
Motor vehicle exhaust contributes 60% of
all CO emissions
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Carbon Monoxide
Carbon Dioxide
 Carbon monoxide is an odourless, tasteless,
colourless gas produced by the incomplete
combustion of carbon compounds.
 It is toxic to humans and can result in death if
you are exposed to it for long periods of time.
 Carbon monoxide will “stick” to your red
blood cells better than Oxygen will, and
therefore you will die from lack of Oxygen.
 Symptoms of CO poisoning include
headache, blue lips and nailbeds, nausea,
confusion.
 CO2 is relatively harmless in small quantities that
we encounter it in the air
 The main concern with CO2 is its greenhouse
effect on the earth, trapping heat in the
atmosphere and changing global climates
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Nitrogen Oxides, NOx
N2 + O2  NOx
 NOx is used to describe NO, NO2 and other
oxides of nitrogen
 NO2 can be seen as a reddish brown layer of air
over cities
 NOx forms when fuel is burned at high
temperatures
 Primary sources are motor vehicles, electric
utilities
 2NO2 (g) + H2O(l)  HNO3(aq) +HNO2(aq)
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NO2 in the atmosphere
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Effects of Acid Rain
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Nitrogen Oxides
Environmental Effects:
NO2 is an component of acid rain
• can damage trees and lakes
NOX reacts with other chemicals (VOC’s,
volatile organic chemicals) in sunlight to
produce ozone
Good ozone occurs naturally above the earth
in the stratosphere, ozone near the ground is
toxic and is the main component of smog
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Nitrogen Oxides
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Catalytic Convertors
Health Effects:
Modern vehicles are equipped with
catalytic convertors that capture the NOx
molecules before they are discharged into
the atmosphere
The interior of the convertor is coated with
a catalyst (palladium, platinum or rhodium)
that react to turn the NOx molecules back
into N2 and O2
2NO(g)  N2(g) + O2(g)
Lung damage
Illnesses such as asthma, bronchitis, and
emphysema
• (sicknesses caused by problems with breathing
passages and lungs)
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Catalytic Converter
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Sulfur Oxides, SOx
S + O2  SOx
 SOx are colourless gases formed by burning
fuels containing sulfur such as coal and oil, and
from industries that use metallic ore, coal or
crude oil for their processes
 SO2 dissolves in water vapour to form acid and
interacts with other gases and particles in the air
to form sulfates which can be harmful to people
and the environment.
 SO2(g) + H2O(l)  H2SO4(aq)
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What are we doing about this?
Other combustion hazards
Decreased allowable air emission levels
for COx, SOx and NOx in Industry.
Enforced emission testing for all vehicles
Alternative clean-burning fuels (H2) or
using renewable energy (electric cars.)
Industrial “Scrubbers” are systems that inject a
Incomplete combustion
Can be a problem in enclosed spaces
Idling cars are not burning fuel efficiently and
therefore produce large amounts of CO and
other toxic gases
Soot from incomplete combustion is an
inhalation hazard
CO is the “silent killer”
dry reagent or liquid into a dirty exhaust stream to "wash
out" acid gases & particulates before they are released
into the air.
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Other combustion hazards
Basic Oxides
House fires and fire fighting
Most metallic elements form basic metallic
oxides
Metallic oxide + water 
metallic hydroxide + thermal energy
Increased use of synthetic materials in the
household produce extremely toxic gases and
particles when they burn
Firefighters wear sealed breathing apparatus to
avoid inhaling the toxins, but some of the toxins
are absorbed through the skin causing health
risks to the firefighters
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Sodium Hydroxide
Calcium Hydroxide
4Na(s) + O2(g)  2Na2O(s) + Energy
CaO(s) + H2O(l)  Ca(OH)2(aq) + energy
Na2O(s) + H2O(l)  2NaOH(aq) + Energy
Calcium oxide (lime), reacts with water to
form calcium hydroxide (slaked lime).
Both calcium oxide and calcium hydroxide
are added to lakes to raise the PH. They
are also used to neutralize acid spills.
Sodium hydroxide is a widely used
chemical
Commonly used in detergents
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Learning Goals
homework
 Elements and their oxides C2.8 plan and
conduct an inquiry to compare the
properties of non-metal oxide solutions
and metal oxide solutions (e.g, carbon
dioxide reacts with water to make water
basic) [IP,PR,AI]
C3.3 explain the chemical reactions that
result in the formation of acids and bases
from metal oxides and non-metal oxides
(e.g. calcium oxide reacts with water to
produce a basic solution; carbon dioxide
reacts with water to produce an acidic
solution)
Read 5.3
Pg 204 # 3-6
Oxides worksheet
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