Rates of Reaction

Fast Reactions - Fireworks.

Fireworks have chemical reactions that are fast
and highly exothermic. The reaction is started
by putting in heat energy (you light the firework).

Some colours in fireworks come from transition metal compounds.
These can be made from neutralisation reactions.
Some colours in fireworks come from other metal compounds.
Magnesium can be used to make a brilliant white flame.
Phosphorous compounds can make fireworks glow brightly.


The solid chemicals in fireworks turn into
large amounts of gas very quickly during the reaction.
The gas has a much bigger volume than the solid chemicals
and this rapid expansion is used in two ways.

Fireworks on the ground use the expansion of gas
to send flames and showers of coloured sparks into the air.

Some fireworks (for example rockets) use the expansion of gas
to send the whole firework into the air where it then explodes
into showers of coloured sparks. The expanding gas coming out
of the bottom of the firework pushes it upwards into the air.

 Fireworks use sound as well as colour for their display.
The different rates at which the chemicals react causes
air molecules to vibrate and produce different sounds.

Alternating layers of fast and slow reacting chemicals
in the firework produce vibrations
in the air which make a whistle or warbling sound.

A very fast rate of turning solids into gas causes
an explosion. A shock wave of sound
travels out through the air producing a loud bang.

Fireworks are a safety hazard. A container for
fireworks would show the hazard symbol for highly flammable.

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