Midsummer Madness - let's burn stuff #7

Dear Human,

Tomorrow is the wonderful Midsummer’s Eve here in Finland. The Midsummer inspired me to write a special Midsummer Edition for this week!

I’ll call this issue Midsummer Madness because it’s full of fire, flames, and burning. On the other hand, these topics are central to our warming climate. We burn organic matter (=fossil fuels) in many forms still today and release carbon dioxide as a result of this burning into the atmosphere.

Before discovering burning reactions, let’s first explore the Midsummer and the summer solstice.  

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Midsummer and the summer solstice

Midsummer is celebrated near the summer solstice. The summer solstice marks the longest day of the year and takes place in the Northern hemisphere in late June.  

Here is a great video that provides a simple, astronomical explanation of the summer solstice.

People have been celebrating Midsummer since the Neolithic period. Stonehenge’s stones align exactly with the summer (and winter) solstice, and it is believed that people gathered at the monument to celebrate these days.

Nowadays, Midsummer is celebrated with big bonfires across European countries.

Midsummer includes awesome festivities, especially in the Nordic and Baltic countries that have not been blessed with sufficient sunlight all year round.

The burning reaction

Okay, it’s time to hop into the science of burning stuff.

Any burning requires three components:

1. Fuel (organic matter like wood or octane, ingredient of gasoline)
2. Oxygen
3. Initial heat to initiate the burning

In chemistry, we can describe burning as a chemical reaction. More specifically, burning is called a reduction-oxidation (redox) reaction meaning that electrons transfer between the atoms.

A great video on the redox reaction by CrashCourse.

To honor the Midsummer, let’s explore burning wood, the fuel for bonfires. In a bonfire, wood acts as the fuel for the chemical reaction.

If we represent wood (in a highly simplified way) as sugar (C6H12O6), the burning reaction will produce carbon dioxide and water.

If there is not enough oxygen available, the burning reaction will be incomplete. As a result, carbon monoxide (CO) gets formed instead of carbon dioxide. Carbon monoxide is deadly to humans when inhaled. That’s why you should keep the chimney damper open long enough after having a fire in your fireplace.

If you want to be entertained by burning wood, flames, and explosions, check out this excellent scientific video by Andrew Szydlo. (By the way, I love the Youtube channel of The Royal Institution. High-quality science videos, where science is made fun and intriguing.)

The release of energy

When you burn wood in a bonfire, a lot of heat energy is released. You can feel it primarily as heat, but also as light and some noise.

All this energy is released because the stored chemical energy of the reactant molecules (here, sugar and oxygen) is higher than that of the product molecules (carbon dioxide and water).

Since energy is conserved, energy equivalent to the difference in the chemical energies gets released to the surroundings mainly as heat.

Note that the number of atoms stays the same before and after the burning. The only thing that changes is the way these atoms bond with each other.

Scientists call this kind of heat releasing reaction as an exothermic reaction.

If you are ready to take a deeper dive into the world of chemistry, enthalpy, and bonding energies, I recommend this video by CrashCourse and this article by LibreTexts.

Harnessing energy

Our humanity harnessed these exothermic reactions of burning organic matter for thousands of years. The first evidence of our ancestors using fire for cooking meat dates back 400,000-300,000 years.  

More recently, we have been burning fossil fuels to power our humanity.

If you are still driving a gasoline or diesel car, you are burning organic compounds, hydrocarbons in your engine to move your car and yourself from A to B. Ever wondered, what happens inside an internal combustion engine? Check out this video.  

Burning gasoline and derivatives of fossil fuels comes unfortunately with harmful consequences for our climate and humankind. As we’ve seen, when organic compounds burn, they release carbon dioxide, a greenhouse gas.

Luckily, there are plenty of ways to produce energy in a more sustainable way like solar. I’m also eagerly waiting for those large scale fusion reactors!  

I hope you enjoyed this special Midsummer Madness edition!

Warm greetings from Yyteri, the Hawaii of Finland, where I’ll spend the rest of the week windsurfing and celebrating Midsummer. Happy Midsummer to you!

Best,

Pauliina

Sources:

• Avitabile et al. The combustion reaction. Link
• CK-12 (2019). Exothermic Reaction.  Link
• Crash Course (2013). Enthalpy: Crash Course Chemistry #18. Link
• CrashCourse (2013). Redox Reactions: Crash Course Chemistry #10. Link
• English Heritage. Understanding Stonehenge. Link 
• LibreTexts (2020). Enthalpy. Link
• National Geographic (2017). What is a Solstice? Link
• Schmidt-Rohr, K. (2015). Why Combustions Are Always Exothermic, Yielding About 418 kJ per Mole of O2. Journal of Chemical Education, 92, 2094-2099. Link
• Scott, A. C. (2018). When Did Humans Discover Fire? The Answer Depends on What You Mean by ‘Discover’. Time. Link 
• SmarterEveryDay. How Engines Work - (See Through Engine in Slow Motion). Link
• The Royal Institution (2018). The Chemistry of Fire and Gunpowder - with Andrew Szydlo. Link