How do fireworks produce colour?

A fireworks display is an explosion designed for maximum visual impact.
Before the oohs and ahs, however, the first challenge is to get a packet of chemical reactants into the sky.
This is usually accomplished with simple gunpowder, lit by a fuse.
The gunpowder is packed so that the resultant expanding gases are forced to escape rearward.
his propels the shell upward until the fuse burns into what's called the burst charge at its core.
The burst charge chemicals explode, lighting and casting in all direction hundreds of stars, small packages of reactants selected to create colour.
The reactants are metallic salts: lithium and strongium produces red; barium nitrates make green; copper compounds result in blue; sodium creates yellow; charcoal and steel produce sparkling gold; and titanium makes white.
The chemicals undergo a fast and violent reaction; bonds among molecules of the solid chemicals break apart, yielding hot, concentrated gases that spread out in a flash, transforming energy into sound, movement, and coloured light.