There’s way more to your morning cup of coffee than meets the eye—or the nose. In fact, it's actually a chemistry lesson in disguise. The American Chemical Society's latest Reactions video explains where the morning beverage's distinctive smell comes from (molecules like the earthy pyrazine, the fruity—yet spicy—methylpropanal, vanillin, and stinky methanethiol all play a part); why milk swirls when it’s poured into a mug of joe; and the reason why plants evolved to make caffeine in the first place (hint: it wasn't to help humans pull all-nighters).

[h/t Reactions]

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