A simplified unbalanced equation for the deflagration a self-propagating burning surface reaction of gunpowder is shown below — re-write this in balanced form. Making the decision to study can be a big step, which is why you'll want a trusted University. Take a look at all Open University courses. If you are new to University-level study, we offer two introductory routes to our qualifications.
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Having already examined the chemical compounds that give fireworks their colours in a previous graphic , I decided to examine another important firework component here: the first chemical explosive, gunpowder, also commonly referred to as black powder. Until the midth Century, gunpowder was the only known chemical explosive.
Its use can be traced much earlier than this, however, and there are historical accounts of its use in fireworks in China as far back as AD. In subsequent centuries it had military applications in rifles and cannons, but in these it has long since been replaced by modern, smokeless powders. The fireworks industry is one of the last major industries that still uses traditional black powder. Rather than being one particular compound, gunpowder is actually a mix of three different components. Each of these components plays an important role in the combustion of gunpowder.
Finally, the sulfur can also act as a fuel, though its inclusion has more to do with the fact that it undergoes exothermic reactions reactions that give off heat at relatively low temperatures, providing more energy and lowering the ignition temperature of the charcoal. Deviations from the ideal ratio given above are sometimes utilised to alter the burning behaviour of the mixture, and the addition of small amounts of water to the mixture can also be used to extend the burning time.
The precise reactions of gunpowder are difficult to elucidate. Rather than being a simple single reaction, the combustion of gunpowder consists of many differing complex reactions. Potassium nitrate is the most important part of gunpowder. This is what propels the firework into the sky. A fuse is used to light the gunpowder, which ignites to send the firework skyward.
Once the firework is in the air, more gunpowder inside it causes it to explode with a BANG! Colours are made by burning metal salts. Did you know that if you burn table salt sodium chloride it makes a yellow flame? The bright sparkles in fireworks come from burning small bits of metal, such as iron or steel filings.
The fuse sets off a charge, which ignites the gunpowder. This propels the firework into the sky. Once the firework is in the sky, the gunpowder within the firework ignites. This causes the 'stars', which contain metal salts and iron filings, to explode in different colours and sparkles. If the firework is in sections, the tars can be in different compartments.
These compartments explode at different times, making different patterns. The pattern of stars around the central gun powder charge creates different patterns of fireworks. For example, if the stars are in a circle around the black powder charge, you get a circle display of colour. One mistake in the placing of the stars and the whole pattern will be ruined!
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