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LuxeSci Show Notes: S1E17: Fireworks

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:

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/


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