6 Chemical Reactions That Changed History


[MUSIC] Physics might show us the universe’s basic
building blocks, and biology lets the universe understand itself, but chemistry is where
all the fun happens in between. We have thousands of chemical reactions going
on inside us every second, but it’s the ones we’ve mastered with our hands, in labs
and workshops and factories and even kitchens, that have made humans what we are today. A
few chemical technologies have made such an explosive change in how we live that they
have altered the very trajectory of humanity. Here’s 6 chemical reactions that changed
history. Fire was our first foray into chemistry, for
better and for worse. Whether it’s animal, vegetable or whatever’s
in hot pockets, cooking our food makes it easier to digest, we get more nutrition for
a lot less work, but there’s a different bit of chemistry that turns food from simple
nutrition into something fun to eat. In 1913, a French chemist named Louis Camille
Maillard described the most delicious reaction I know of. Pretty much everything we cook
contains sugars and amino acids, and when they react at high temperatures, the result
is… well, hundreds and hundreds of complex flavor compounds. It’s what browns grilled
hamburgers, puts the crispy crust on pizza, the golden edges on french fries, the… sorry,
I got a little carried away there. Anyway, sure, harnessing fire made food more
digestible, but the Maillard reaction made it more fun to eat, and drink, because really,
where would we be without roasted coffee? “Dogs and cats, living together, mass hysteria!” They say sticks and stones can break bones,
but metal does it much better. If your ancestors didn’t figure out the chemistry of bronze,
they were probably conquered by someone who did. The only pure metals that Earth has any good
amount of are copper, gold, silver, and platinum, but unfortunately they’re all either too
valuable, too heavy, or too soft to make good pokey sticks with. Beginning 5 to 6 thousand years ago, people
began alloying, or mixing copper with elements like tin, to make bronze, a step up in hardness
and durability from pure copper. It was later replaced by iron in most uses, but bronze
was the beginning of humanity’s heavy metal stage. Ya like civilization? I’m a big fan myself,
and one reaction above all others made it possible.
As the poet John Ciardi put it: “Fermentation and civilization are inseparable.”
Our ancestors eventually got tired of chasing dinner and were finally able to put their
roots down by putting some roots down. Domesticating plants led to a nice orderly system where
a few people grow enough food for everyone, giving others free time to explore things
like art, advanced government, and even science, or at least what passed for science at the
time. But eating raw grain is not our thing, and
what good is that harvest if it’ll be rotten in a couple weeks
By harnessing fermentation, and converting sugars into acids, alcohol, and gas our ancestors
let tiny creatures they had no idea even existed turn fruit, vegetables, grain, and even milk
into forms that were tastier and lasted longer. You know what’s also nice? Drinkable water.
But for most of human history, drinking from the wrong stream or well could get you the
last stomach ache you’d ever have. Fermentation and its antimicrobial alcoholic by products
were your friend. Considering water used to be an actual health
hazard, it’s no surprise that bathing often wasn’t high on priority lists of the past.
But nobody wants to sit with the smelly kid, even in ancient Sumeria. Tablets dating from
nearly 4,000 years ago there show formulas for mixing water, alkali ash, and oil or animal
fat to make soap. Plant and animal oils are triglycerides, a
glycerol molecule plus three fatty acids. Break them in with the alkali base, and you
get fatty acid salts, the key ingredient in soap, because they dissolve both ways. One
end is attracted to water, and the other attracts greasy nonpolar things, and the resulting
chemical mix is perfect for using water to pull olive oil stains out of your favorite
toga. News flash: Computers are a big deal, and
neither cell phones or smart thermostats would be possible without silicon chips. Silicon
is actually super easy to find, but to be used in chips it has to be super pure. How
pure? At least nine nines pure. But that’s not even the hard part. Pure solid silicon is a mass of billions of
separate crystals. It looks cool, but everywhere two crystals meet is a place where semiconductor
magic can’t happen. The Czochralski process makes that mess chip-worthy. The silicon is
remelted, and a single tiny crystal is lowered in and slowly drawn out. This first crystalline
seed aligns the growing solid mass in a single, perfect crystal of silicon, ready to be sliced
and diced and put to good use. Everything that’s alive needs nitrogen in
order to build the most basic bits of life like amino acids and DNA. But for most of
life’s history, converting nitrogen to biologically useful forms could only be done by bacteria
in soil, they pull gas from the air and convert it to building blocks like ammonia and nitrates. That was until 1909, when German chemist Fritz
Haber, with the help of a couple friends, figured out how to do it on our own. The Haber-Bosch
process converts nitrogen gas and hydrogen gas, two simple ingredients, to make ammonia,
which we can then turn into an N-finite list of useful stuff. So why is this #1? Fertilizer. For the first
time, farmers didn’t have to rely on crop rotation or shovel what the family cow provided
‘em to get nitrogen. Inexpensive chemical fertilizers let many people grow abundant
food for the first time ever. The world grew so much food, in fact, that the global population
has more than quadrupled since this chemical revolution. We make 450 million tons of nitrogen
fertilizer this way every year, a full 1 to 2 percent of all the energy we use goes to
this process. Of course salad bars and cereal aren’t the
only thing that we make with industrial nitrogen. Nitrates are necessary ingredients in making
explosives, and the Haber process allowed the nations involved in WWI and II to unleash
destruction on scales never seen before. But whether it was the battlefield or the
breakfast table that really motivated Haber to harness nitrogen from air, one explosion
definitely won out over the other, and it’s just one delicious bit of chemistry that feeds
our brains every day. Now if you enjoyed these Fine reactions, I
know we skipped over a lot of important historical chemical wonders, so let us know in the comments
what you think changed humanity more than any other reaction. Stay curious.

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