REACTIONS
OF METALS
WITH OXYGEN
COMBUSTION
BURNING OF
METALS
RECAP

Chemical reactions can be represented using
models and chemical formulae

Another method is the word equation

Consider the following reactions

SO2 + O2 → SO3

Li +H2SO4 → Li2SO4 +H2
General
equation
Metal plus oxygen form metal
oxide
Metals are shiny, brittle, strong,
durable, and good conductors of
electricity
Oxygen is a gas at room
temperature, a diatomic element,
and makes up 20% of the air.
Short activity
1)
Write the word equation for the reactions that take place when
the following metals burn in the air.
b. lead
c. mercury
e. beryllium
2) Complete the following chemical equations and balance them
a. Cu + O2 → ……..
b. Ca + O2 → ……
c. Li + ……. → Li2O
Examples of metal
oxide

SODIUM REACTS WITH OXYGEN TO
FORM SODIUM OXIDE
Potassium oxide

K+O2 → K2O
Calcium
oxide
Ca + O2 →CaO
https://youtu.be/dszSKIM5rqk
Zinc oxide
Zn+ O2→ ZnO
https://youtu.be/Y12R0EgOJOo
Rusting
How can we identify
rust?
Metals corrode and weakens.
Example is iron
when Fe is exposed to oxygen it reacts with it to
produce an orange-brown powder called rust.
Under wet conditions or in moist environments iron
rusts more quickly
Why do you think people staying in Cape Town or
near the coast should use wooden building materials
rather than those made of steel?
NOTE:

Rusting tends to happen much faster near the
ocean. Not only are there water droplets, but
these droplets have salt in them, and this
makes them even more corrosive. Rusting
also happens more quickly in the presence of
acids. Inside laboratories, or factories where
acids are used or stored, the air is also very
corrosive. When the air in a specific area
contains moisture mixed with acid or salt, we
refer to the area as having a corrosive
climate
How can we
prevent
rusting?
1.Painting

The paint creates a
barrier between
metal, water, and
oxygen. However, the
underneath corrode if
the paint is scratched.
Galvanizing

How can we slow down the process of
rusting? Which element can we use?

Coating metals by dipping them in a
molten(melted zinc) which creates a layer of
zinc oxide. https://youtu.be/j91XEGbFgQY

Example: corrugated sheets
Oiling

what can you do to
prevent the chains of your
bicycle from rusting?

Does water and oil mix?

applying a protective coating, such
as oil can create a barrier between
the metal and the surrounding air,
preventing oxidation and the
formation of rust.
electroplating
https://youtu.be/FnJ0V7B7nKo
Adding a layer or chrome or zinc by electrolysis
Zinc or tin coatings may be
applied to confer corrosion
resistance. electroplating is
performed to increase the
thickness of an item
reflective questions
How are ships protected from rusting?
How do you think rusting affects the South
African economy?
Thank you

Next session reactions of nonmetals with oxygen