Hello and welcome back to LuxeSci, a podcast to re-ignite your wonder by exploring the science behind luxury items.
So we’re a little late with getting this episode out due to some travel that went a bit awry, as most travel is doing these days. But the silver lining on that is our podcast is now timed for around the July 4th holiday and we can delve into the explosive world of fireworks. (Now I know that there are many that don’t feel like feting our country’s founding this year but fireworks are used for all sorts of occasions so pick one you like).
Dimos - what have you wondered about fireworks?
Alexis - I’ve wondered about how they pack them so that you get all sorts of partners, etc
Dimos - do you have a story about fireworks?
I think my fondest memory of fireworks is stopping at the New Hampshire border on our way to Maine and stocking up on fireworks. We would take them down to the lake that we were staying near and set them off. My brother and cousin would make a big show and arrange and time them. It was their pyrotechnic extravaganza and it was so fun, with a bonfire and smores and everything.
Background and Science:
Dimos
Additional Science:
Pyrotechnics are not just for fireworks. They are also used in flares, airbags and even matches
Pyrotechnics are oxidisers (such as metal nitrates and perchlorates) and a reducing agent/fuel, (carbohydrates, non-metals, etc) along with binders, propellents and colors and smokes for effect
Oxidizer - a substance that gains or receives an electron from a reducer or one that undergoes a chemical reaction where it gains one or more electrons
Reducing agent - substance that donates an electron to an electron recipient
Redox reaction - the chemical reaction in which oxidation and reduction takes place. These reactions are very important biological (cellular respiration is oxidation of glucose and reduction of oxygen to water) and in geology (where minerals are oxidized derivatives of metals and the minerals must be reduced to get the metals).
For pyrotechnics to work, the ingredients must be mixed. The manufacturing common practice has been to tumble dry powders together or mix a slurry of wet components with horizontal and vertical blades
A research team (Blair et al) looked for a new way to mix the components of pyrotechnic materials to ensure a more homogenous mixture and published their results in Chemical Communications (Cambridge) in 2015
They used a crystal lattice to stabilize the mixture and produce one with the requisite ratios and minimal batch-to-batch variability
This was done by using metal-organic frameworks - compounds of metal ions coordinated to organic ligands to form various structures
The team used frameworks containing fuel and oxidizing agents to produce the desired effects
Now some bad news about fireworks
In a 2020 study published in Particle and Fiber Toxicology and authored by Christine Hickey et al, emissions from 10 different fireworks displays were collected and tested in vivo and mice
Reactive oxygen species were produced in response to the particulates in both the human airway cells and the bronchial epithelial airway in mice
Reactive oxygen species - byproducts of oxygen metabolism and are important in cell signaling and homeostasis
They can cause irreversible damage to DNA
It seems that the emissions from fireworks (organic compounds and metals) may be contributing to the particulate pollution in the air and could have deterimental impacts to human and animal health
I will say that this particular study did not do a lot of replicates in their research and only 8 mice so more work is needed to verify this finding
Interestingly - there have been cases of acute barium toxicity from individuals ingesting fireworks. A case study published in Indian Pediatrics in 2012 highlighted a case of a teenage boy who presented with gastroenteritis, pain in the abdomen, difficulty breathing and generalized weakness
The cause is severe hypokalemia due to redistribution of potassium in the body
Hypokalemia - low level of potassium in the blood. It increases the risk of abnormal heart rhythm and can lead to cardiac arrest
As a reminder - fireworks can be extremely dangerous. 15,600 people ended up in the ER in 202 for fireworks-related injuries (Consumer Product Safety Commission) So please use caution and have plenty of water around to extinguish errant fireworks if you’re planning on using some this summer
Dimos’s Notes:
Greek tradition of fireworks:
Protofireworks chemistry:
Chinese augmented fireworks with a special array of chemicals: salt-peter, potassium nitrate. Fire needs fuel, heat, and oxygen.
The key invention is Potassium Nitrate:
One Nitrogen Atom, One Potassium Atom, Three Oxygen Atoms. Combustion process is a result of an oxygen donor. Atmospheric oxygen is limited to surface access. Oxidizer effect created by salt-peter. Charcoal and sulfur along with salt-peter can create a great explosion.
Gunpowder was used in Chinese medicine for skin problems
Salt-peter was and is used to preserve salami.
Building fireworks:
Paper was very important for creating fireworks but it was expensive, bamboo paper was cheaper.
Changing sizes of pellets of metal salts that are packed with the gunpowder can change the resulting pattern of sparks.
Typical firework would consist of black powder and ‘stars’ in a tight paper tube with a fuse to light the powder. Stars can be made into any shape and size. Imagine a simple star as something like a sparkler compound formed into a ball the size of a pea or a dime. The stars are poured into the tube and then surrounded by black powder. When the fuse burns into the shell, it ignites the bursting charge, causing the shell to explode. The explosion ignites the outside of the stars. Each star begins to burn with bright showers of sparks or as a single hot ember. Since the explosion throws the stars in all directions, you get the huge sphere of sparkling light or pattern display. Controlling the direction of the balls allows for geometric shapes to occur.
Elements
Sparklers: Aluminum
Antimony: glitter
Sparks: iron
Zinc: smoke effects
Colors?
Red = strontium carbonate or Lithium
Orange = calcium chloride
Yellow = sodium
Green = Barium
Blue = copper chloride
Violet = mix of copper and strontium
White = titanium zirconium and magnesium
Shapes:
to create the shapes, stars are arranged on a piece of cardboard in the desired configuration. If the stars are placed in a smiley face pattern on the cardboard, for example, they will explode into a smiley face in the sky. In fact, you may see several smiley faces in the sky at one time. With shaped fireworks, pyrotechnicians often set off several at the same instant to ensure the shape can be seen from all angles. Spectators with the cardboard lined up along their line of sight may only see a burst of light or stars rather than the desired shape. If several go off at once, one of them should be oriented correctly at the moment it bursts so the crowd can see the shape [source: https://www.livescience.com/33369-fireworks-shapes-patterns-pyrotechnics.html].
Core explosive with blackpowder
Lift-charge with fuse to center charge.
Explosive balls called stars create patterns depending on how they are packed.
Glossary:
Oxidizer - substance that gains an electron
Reducing agent - substance that gives an electron
Redox reaction - chemical reaction where oxidation and reduction occurs
Reactive oxygen species - forms of metabolized oxygen
Hypokalemia - low level of potassium in the blood
Fun facts:
Whelp, you’ve done it, spent another 20+ minutes with Dr. Dimos and I and the awe-inducing subject of fireworks. We hope you remember a little cocktail party fact about them the next time you get to oooh and aaah and a fireworks display.
A very special thank you to my cohost and audio engineer Dimos. Our theme music is Harlequin Moon by Burdy. If you like us, please, please, please subscribe and rate us wherever you listen to your podcasts.
You can find us all over social media at luxescipod and our website.
Please take a minute to share us with the person sitting next to you and the next fireworks display you attend.
References:
https://en.wikipedia.org/wiki/Redox#Redox_reactions_in_biology
https://core.ac.uk/reader/42584060
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7330945/
https://www.indianpediatrics.net/sep2012/762.pdf
https://science.howstuffworks.com/innovation/everyday-innovations/firework-shapes.htm
As we noted on the show, we are in support of people with a uterus and their right to make their own reproductive decisions. This also follows the evidence generated by studies of abortions. You can find more information here: https://www.scientificamerican.com/report/the-science-of-abortion-rights/
If you'd like to help, here are some organizations to support: https://www.rollingstone.com/culture/culture-news/abortion-funds-to-donate-to-how-to-help-1351451/
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