The Properties of Fireworks Explosions - Term Paper Example

?Fireworks Introduction Fireworks are a group of pyrotechnic devices invented by the Chinese Sung dynasty. They have been used for public displays, personal entertainment and religious purposes. They have also been used in agriculture to scare off birds. The composition is mainly of highly combustible and explosive compounds that combine to produce the effects of brilliant colors, sound and smoke. 2) Properties The properties of firework explosions are force, velocity and heat. The combusting components undergo rapid entropic change, and thus this lends to the term “firework explosion.” The forces produced are generated by the rapid evolution of gases and heat that force them to expand according to the combined gas law (PV/T=k) where p is pressure, V=volume and T is temperature. The force of explosion is a component of the gas pressure. It is exerted equally in all directions obeying Pascal’s principle. Therefore, P=F/A where the ‘A’ is the area of confined combustibles. The force is responsible for the launching of the fireworks, their dispersion velocity and sound (report). Heat is a consequence of combustion and exothermic reactions such as oxidation and thermite-like redox reactions with the firework. The total summation of the energies produced obeys the first law of thermodynamics by adhering to the basic principle of “conservation of energy” 3) Hypothesis Fireworks are manufactured by compounds that are toxic, flammable and environmentally hazardous, and thus unsafe. 3) Composition Fireworks are generally composed of three chemical compounds; a fuel, an oxidizer, color producing compounds, a chlorinator and a binder. Manufacture of the fireworks is mainly done using chemicals that are non-toxic. Some compounds though, elicit high reactivity and toxic properties if handled directly. As will also be seen in later sections, the reactive products given off some other compounds are toxic. The fuel is the main component that allows the fireworks to burn. It is composed of sulphur, carbon based compounds, or metals. Phosphorous is also added to some fireworks for its glow in the dark properties. The most common metals are aluminum and magnesium. These burn brilliantly and are therefore preferred to others such as titanium. They are also cheaper. Often, the alloy, Magnalium is used. This is because magnesium does not form a protective oxide coat. This can be directly attributed to its high reactivity and thus higher risk of uncontrolled combustion. It may also cause serious burns and blindness due to its characteristically high temperatures and brilliance on combustion. The oxidizer is the accelerant used to make the burn more intense and violent. Potassium compounds are mostly preferred for this purpose. They include the nitrates, perchlorate, chlorate and peroxides. The potassium ions may also impart a pink color to the flame. Direct contact with these compounds may cause an oxidizer burn to human skin or any organic material. Not to mention the fire risk if exposed to already combustible organic materials such as cloth, natural gas or dry grass. The colour imparting compounds are mainly metals. Their cations are the main contributors of the color. Their anion compounds determine how brilliantly they burn. Examples are the chlorides and nitrates that enhance brilliance. Carbonates and oxalates reduce brilliance. This is also where the aspect of toxicity emerges. a) Infra-red color- rubidium nitrate- it is not directly toxic, but is capable of oxidizing compounds b) Silver/ white- antimony sulphide- exists as stibnite and the antimony pentasulphide. The pentasulphide is flammable and can have potentially toxic effects on reacting with strong acids such as HCl. The reaction produces hydrogen sulphide which is a potent nerve toxin. HCl is naturally found in the stomachs of many mammals as a component of gastric juice. The pentasulphide is thus potentially harmful if ingested. The stibnite form is also potentially toxic c) Blue- copper arsenite- the compound is toxic, and this can be directly attributed to the arsenic. d) Green- barium oxalate, barium chloride and barium chlorate- the barium oxalate compound is a skin irritant. It is also toxic on ingestion, and may cause nausea, renal failure and gastrointestinal destruction. The chlorate and chloride are also toxic like most barium salts. The chlorate is a skin irritant due to its oxidative properties. e) Red- strontium oxalate- the compound is a known irritant to mucus membrane when inhaled, as well as an eye irritant. f) Yellow- sodium oxalate- sodium oxalate is toxic to humans. This is similar to most other oxalates when ingested. It is known to cause bloody vomiting, headache, muscle cramps, shock, coma, hypotension, convulsions and possible death. g) Gold/yellow- Iron and charcoal- these are normally not toxic. In few scenarios though, Iron may cause iron toxicity when consumed in large amounts. h) Orange- calcium carbonate- the compound is not known to be toxic. It is found in nature in crustacean shells, limestone rocks, human otoliths and as the main component of eggshells. Other compounds include clay, bismuth compounds, ammonium nitrate, acetone, dechlorane, Gallic acid and saw dust. Some of these compounds are also quite toxic and flammable (Bradley). Other effects of fireworks use include the associated noise, light, smoke and fire hazards. The explosions by the combustion of compounds may easily lead to deafness at close range. The noise is also considered a disturbance in most neighborhoods, unless quantified by presence of ongoing festivities that warrant firework use. The elderly and young are the most affected. Environmental disturbance to animal habitats is also a risk. Birds are especially at risk due to their susceptibility to the loud noises and lights. Domestic animals and pets have also been known to be susceptible to frights causing them to be vicious and sometimes destructive (Health). Light from fireworks may not be a problem when they are displayed in the right way. They may cause blindness if mishandled or used at close range, especially if they contain magnesium and aluminum compounds. Smoke and fire hazards are often encountered together. The smoke and dust produced by fireworks contains heavy metals, sulphur, carbon and toxic products of combustion. This is especially true of the barium burning fireworks. Antimony and perchlorates may also find their way into water sources and cause toxicity to aquatic life. The smoke produced may cause asthmatic attacks to susceptible individuals, though this is quite rare. Fire hazards are more common due to mishandling or misfire of fireworks. These are mostly individual burns or open fired due to fireworks landing in combustible compounds like hay or grass fields. According to the National fire protection agency (NFPA) data, during 2006-2010, the largest outdoor fires were associated with grass fires, brush fires and dumpster fires. In the same years, 5 people per year were killed by firework related fires and accidents (NFPA). Debris left from fireworks may also cause environmental pollution concerns. These include polythene wrappers and plastic casings from exhausted fireworks. As seen above, the compounds in fireworks are potentially toxic to humans and animals alike. It is wise to note that many safety precautions are in place to prevent such hazards from becoming actual risks. These include the legislature imposed by the Bureau of Alcohol, tobacco, firearms and explosives (U.S.), Consumer product Safety Commission (U.S.) 16) Research Further research into the safety of fireworks needs to be done with regard to its toxic effects on the manufacturers, consumers and the environment. This includes the search for less toxic oxidizing agents (perchlorates) and colorants (barium and arsenic). REFFERENCES Colin Bradley. “pyrotechnic chemicals.” Pyrotechnic chemical guide, 2004. www.pyrouniverse.com/chem.htm. 30/11/2013 Surrey Health. “fireworks safety, law and noise.” Surrey Health, 2012. www.surreyheath.gov.uk. 1/12/2013 John R. Hall. “Fireworks.” National Fire Protection Agency, June 2013. http://www.nfpa.org/research/statistical-reports/major-causes/fireworks. 2/12/2013 Read More