GCSE CHEMISTRY - Fireworks have Very Fast Reactions - Chemical Compounds produce Colours and Sounds

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Fast Reactions - Fireworks.

Fireworks have very fast chemical reactions that are
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. Some of these can be made as salts 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 that 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 that is blasted 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 chemicals in the firework react at
different rates and this causes air molecules to vibrate
at different rates and produce different sounds.

Alternating layers of fast and slow reacting chemicals
inside the firework can produce vibrations
in the air which make a whistling 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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