Chemistry Presentation - The Chemistry of Fireworks

THE
CHEMISTRY OF
FIREWORKS
Where it all began
The discovery of fireworks is believed to have

occurred approximately 2,000 years ago in China.
It is thought that a Chinese cook accidentally mixed

three common kitchen ingredients…
KNO3 SULFUR CHARCOAL
These were heated over a fire and dried to give a

black flaky powder which burned with a loud bang
when ignited. This crude, early mixture has come to
be known in our modern world today as gun powder.
ITEM OF PEACE OR WAR? (1)
Within 100 years the Chinese had developed fire
arrows and other such firearms from the explosive.
Roger Bacon an English Scholar realized that Salt

Peter (KNO3) was the key to the explosive power.
In 1560, European Chemists made gunpowder as

explosive as possible by developing a new kind of
ratio proportion…
ITEM OF PEACE OR WAR? (2)
The final proportion was set as follows:
These ratios are still used today after 500 years
‘Saltpeter’
SULFUR CHARCOAL
KNO3
10% 15%
75%
It was the Italians who made Fireworks what they are

today
Aerial shells that launched upward and exploded into a
fountain of color, lighting up the night sky
The evolution of Fireworks
For nearly 2,000 years, the only colours fireworks
could produce were yellows and oranges
Using steel and charcoal.
In the 19th Century, pyro-technicians developed the

technology to introduce reds, greens and blues to the
firework displays
What’s inside a
Firework?
Theory of Combustion
The Chemistry of fireworks is based on the theory of
combustion:
Combustion is the sequence of exothermic chemical reactions
between a fuel and an oxidant accompanied by the production of
heat and conversion of chemical species. The release of heat can
result in the production of light in the form of either glowing or a
flame.
The composition inside the firework must however

contain 6 vital ingredients…
Fuel Oxidizing
Agent
Reducing
Binder
Agent
Coloring
Regulator
Agent
THE
END
Firework Fuel (1)
Normally, all fuels will contain an organic element
such as charcoal or thermite. Charcoal (a.k.a. black
powder) is the most common fuel used in fireworks.
The fuel loses electrons to atoms within the oxidiser

(thereby reducing the oxidiser) and releasing atoms
from the oxidiser.
During this process, bonds are formed between the

fuel and oxygen atoms forming a product which is
relatively stable.
Firework Fuel (2)
Only a minimal amount of energy is required to start the
combustion of this fuel-oxidiser compound.
When combustion does start, the result is a massive

release of energy as the solid mixture liquefies and
vaporizes into the flame of ignition.
This maximizes the probability of reaction of the

oxidizer as it is brought into the close proximity of the
flame.
BACK
Oxidising Agents (1)
The function of the oxidising agent is to produce the
oxygen needed in order for the mixture inside the
firework to burn.
These oxidisers can be nitrates, chlorates or

perchlorates.
XNO3 XNO2+ ½ O2
Nitrates only give up a third of their oxygen as the
equation above illustrates.
Chlorates get completely reduced as they are better

oxidising agents and so cause an even more
spectacular reaction.
2XClO3 2XCl + 3O2

Perchlorates contain even more oxygen but are less
likely to explode than chlorates due to their increase
in stability.
They follow the reaction below:
XClO4 XCl + 2O2
BACK
Reducing Agent
These burn the oxygen provided by the oxidising
agents to produce hot gasses.
Common reducing agents are Sulphur and Charcoal.
These react with the oxygen to form Sulphur dioxide

and Carbon dioxide respectively:
S+O2 - SO2
C+O2 - CO2
By mixing both the reducing agents, the speed of the
reaction can be controlled.
Regulators
Metals can be added to regulate the speed at
which the reaction. The larger the surface area of
the metal, the faster the reaction will proceed
(collision theory).
BACK
Colouring Agents (1)
Different chemicals are used to produce different coloured
fireworks.
In order to produce a firework of a certain colour, the correct

corresponding chemical or as the case may be, mixture of
chemicals can be used.
The incandescence from the elements occurs when solid

particles are heated in the flame to extremely high
temperatures. These release excess energy in the form of
light (hv) at the broad end of the spectrum.
Metal Colour
Strontium Red
Copper Blue
Barium Green
Sodium Yellow/Orange
Calcium Orange
Iron Gold
Strontium + Copper Purple
The incandescence from the elements occurs when
solid particles are heated in the flame to extremely
high temperatures.
These release excess energy in the form of light (hv)

at the broad end of the spectrum.
The higher the temperature, the shorter the

wavelength at which light is emitted, and the nearer
it tends toward the blue end of the coloured
spectrum.
BACK
BINDERS
Binders are used to hold what is essentially the
mixture of the firework together in a paste like
mixture.
The most commonly used binder is known as

dextrin.
The binders do not actually begin to work until the

firework has been lit as they are too unstable for
storage within the firework and are hence potentially
dangerous.
BACK
THANK YOU

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THE

The discovery of fireworks is believed to have

It is thought that a Chinese cook accidentally mixed

These were heated over a fire and dried to give a

Roger Bacon an English Scholar realized that Salt

In 1560, European Chemists made gunpowder as

It was the Italians who made Fireworks what they are

In the 19th Century, pyro-technicians developed the

The composition inside the firework must however

The fuel loses electrons to atoms within the oxidiser

During this process, bonds are formed between the

When combustion does start, the result is a massive

This maximizes the probability of reaction of the

These oxidisers can be nitrates, chlorates or

Chlorates get completely reduced as they are better

2XClO3 2XCl + 3O2

They follow the reaction below:

XClO4 XCl + 2O2

Common reducing agents are Sulphur and Charcoal.

These react with the oxygen to form Sulphur dioxide

In order to produce a firework of a certain colour, the correct

The incandescence from the elements occurs when solid

These release excess energy in the form of light (hv)

The higher the temperature, the shorter the

The most commonly used binder is known as

The binders do not actually begin to work until the

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